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LECTURE 1LECTURE 1

INTRODUCTION TO GEOLOGY 11INTRODUCTION TO GEOLOGY 11

WHAT IS GEOLOGY?WHAT IS GEOLOGY?

Geology is the study of the Earth, the processes that shape it, and the resources that could be obtainedGeology is the study of the Earth, the processes that shape it, and the resources that could be obtained

from it.from it.

GEOLOGY AS A DISCIPLINEGEOLOGY AS A DISCIPLINE

-- the relevance of timethe relevance of time

-- the issue of scalethe issue of scale-- the complexity of replicating natural systems and phenomena in the laboratorythe complexity of replicating natural systems and phenomena in the laboratory

THE MAIN BRANCHES OF GEOLOGYTHE MAIN BRANCHES OF GEOLOGY

PHYSICAL GEOLOGYPHYSICAL GEOLOGY

- deals with the materials that comprise the Earth and the processes that affect it- deals with the materials that comprise the Earth and the processes that affect it

-- Volcanology, SeismologyVolcanology, Seismology-- Environmental Geology, Engineering GeologyEnvironmental Geology, Engineering Geology-- Mining Geology, Petroleum GeologyMining Geology, Petroleum Geology-- Mineralogy, PetrologyMineralogy, Petrology-- GeomorphologyGeomorphology

--

Geophysics, Geochemistry, Planetary GeologyGeophysics, Geochemistry, Planetary Geology

2.2. HISTORICAL GEOLOGYHISTORICAL GEOLOGY

- the study of the origin and evolution of the Earth through time- the study of the origin and evolution of the Earth through time

PaleontologyPaleontology

StratigraphyStratigraphy

GeochronologyGeochronology

BASIC CONCEPTS IN THE HISTORY OF GEOLOGYBASIC CONCEPTS IN THE HISTORY OF GEOLOGY

-- CatastrophismCatastrophism- proposed by Baron- proposed by Baron Georges CuvierGeorges Cuvier

- advocates the idea that sudden, worldwide- advocates the idea that sudden, worldwide catastrophescatastrophes are theare the agents of changeagents of change that alter thethat alter the

physical features of the Earth over time and that the latter remains unchanged in between thesephysical features of the Earth over time and that the latter remains unchanged in between these

periods of upheavalsperiods of upheavals

- widely accepted by theologians in the early 1800s due to similarity with Biblical events such as the- widely accepted by theologians in the early 1800s due to similarity with Biblical events such as the

Noachian FloodNoachian Flood

-- UniformitarianismUniformitarianism- proposed by- proposed by James HuttonJames Hutton (The Father of Modern Geology)(The Father of Modern Geology)

- often condensed to, - often condensed to, The present is the key to the pastThe present is the key to the past ..

- advocates the idea that the Earth is continuously modified by geologic processes that have always- advocates the idea that the Earth is continuously modified by geologic processes that have always

operated throughout time (albeit at different rates), and that by studying them we can understandoperated throughout time (albeit at different rates), and that by studying them we can understand

how the Earth has evolved through timehow the Earth has evolved through time

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LECTURE 2LECTURE 2

THE PLANET EARTHTHE PLANET EARTH

THE FORMATION OF THE EARTH WAS AN OFFSHOOT OF THE FORMATION OF THETHE FORMATION OF THE EARTH WAS AN OFFSHOOT OF THE FORMATION OF THE

UNIVERSEUNIVERSE

Formation of the Universe:Formation of the Universe: Big Bang TheoryBig Bang Theory

Formation of the Solar System:Formation of the Solar System:Nebular HypothesisNebular Hypothesis

THE BIG BANG THEORYTHE BIG BANG THEORY

-- contends that the Universe originated from a cosmic explosion (origin unknown) that hurledcontends that the Universe originated from a cosmic explosion (origin unknown) that hurledmatter in all directions 15 and 20 billion years agomatter in all directions 15 and 20 billion years ago

-- first proposed by the Belgian priest Georges Lematre in the 1920sfirst proposed by the Belgian priest Georges Lematre in the 1920s

-- Edwin Hubble justified Lematres theory through observations that the Universe is continuouslyEdwin Hubble justified Lematres theory through observations that the Universe is continuouslyexpanding; galaxies are moving away from each otherexpanding; galaxies are moving away from each other

THE SOLAR SYSTEM: leftover from the Big BangTHE SOLAR SYSTEM: leftover from the Big Bangthe sunthe sun

the planetsthe planets

the satellites and ringsthe satellites and rings

comets and asteroidscomets and asteroids

meteoroids and dustmeteoroids and dust

COMPOSITION OF THE SOLAR SYSTEM BY MASSCOMPOSITION OF THE SOLAR SYSTEM BY MASS

OBJECTOBJECT PERCENTAGE OF MASSPERCENTAGE OF MASS

SunSun 99.85%99.85%

JupiterJupiter 0.10%0.10%

all other planetsall other planets 0.04%0.04%

cometscomets 0.01% (?)0.01% (?)

satellites and ringssatellites and rings 0.00%0.00%

asteroidsasteroids 0.00%0.00%

meteoroids and dustmeteoroids and dust 0.0000001% (?)0.0000001% (?)

THE NEBULAR HYPOTHESISTHE NEBULAR HYPOTHESIS

-- the solar system originated from a single rotating cloud of gas and dust, starting 4.6 billion yearsthe solar system originated from a single rotating cloud of gas and dust, starting 4.6 billion years

ago, which contracted due to gravityago, which contracted due to gravity

-- the idea was first proposed bythe idea was first proposed by Immanuel KantImmanuel Kant andand Pierre Simon de LaplacePierre Simon de Laplace in the 18th centuryin the 18th centuryTHE NEBULAR MODELTHE NEBULAR MODEL

Time 1: The Big Bang produced enormous amount of matter: rotating cloud of gas and dust.Time 1: The Big Bang produced enormous amount of matter: rotating cloud of gas and dust.

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Time 2: The rotating gas-dust cloud began to contract due to gravity. Most of the mass becameTime 2: The rotating gas-dust cloud began to contract due to gravity. Most of the mass became

concentrated at the center, forming the SUN.concentrated at the center, forming the SUN.

Time 3:Time 3:The remaining matter condensed to form the planets.The remaining matter condensed to form the planets.

THE SUNTHE SUN

-- mostly made up ofmostly made up ofhydrogenhydrogen, the principal product of the Big Bang, the principal product of the Big Bang

-- suns center became compressed enough to initiatesuns center became compressed enough to initiate nuclear reactionsnuclear reactions, consequently emitting, consequently emitting lightlightand energyand energy (sun became a(sun became a starstar))

-- aa middle-aged starmiddle-aged starTHE PLANETSTHE PLANETS

-- composition depended on distance from the suncomposition depended on distance from the sun

-- planetsplanets nearest the sunnearest the sun containedcontained high-temp mineralshigh-temp minerals (e.g., iron) while those that are(e.g., iron) while those that are far awayfar awaycontainedcontained lower-temp materialslower-temp materials (e.g., methane and ammonia, and some that contained water(e.g., methane and ammonia, and some that contained water

locked in their structures)locked in their structures)

1.inner or terrestrial planets (nearest the sun)1.inner or terrestrial planets (nearest the sun)

- rocky composition: largely silicate rocks and metals (Si, Fe, O)- rocky composition: largely silicate rocks and metals (Si, Fe, O)

- Mercury, Venus, Earth, Mars- Mercury, Venus, Earth, Mars

2. giant or Jovian planets (outer planets; far from the sun)2. giant or Jovian planets (outer planets; far from the sun)

-- lack solid surfaces: in gaseous or liquid formlack solid surfaces: in gaseous or liquid form-- composition: light elements (H, He, Ar, C, O, Ni)composition: light elements (H, He, Ar, C, O, Ni)

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-- Jupiter, Saturn, Uranus, NeptuneJupiter, Saturn, Uranus, Neptune*neither a terrestrial or Jovian planet*neither a terrestrial or Jovian planet

- similar to the icy satellites of the Jovian planets- similar to the icy satellites of the Jovian planets

- Pluto- Pluto

SOME INTERESTING FACTSSOME INTERESTING FACTS

1. Planets1. Planets revolutionrevolution == counterclockwise directioncounterclockwise direction..

2. Planets2. Planets rotation directionrotation direction the same asthe same as direction of revolutiondirection of revolution except forexcept forVenusVenus, which rotates, which rotates

in ain a retrograde directionretrograde direction..3.3. Uranus and PlutoUranus and Pluto rotate aboutrotate about axesaxes that arethat are tipped nearly on their sidestipped nearly on their sides..

4. Orbital Speed of the Earth = 30 km/s4. Orbital Speed of the Earth = 30 km/s

THE EARTHTHE EARTH

-- started as dust ball from the nebular gas and dust brought together by gravity (started as dust ball from the nebular gas and dust brought together by gravity ( accretionaccretion),),which was heated (which was heated (heatingheating) and eventually segregated into layers () and eventually segregated into layers (differentiationdifferentiation) as it cooled) as it cooled

-- when cooling set in, the denser elements (e.g., iron) sank while the lighter ones floated out intowhen cooling set in, the denser elements (e.g., iron) sank while the lighter ones floated out intothe surface, creating a differentiated Earththe surface, creating a differentiated Earth

THE DIFFERENTIATED EARTHTHE DIFFERENTIATED EARTH

CONSEQUENCES OF THE HEATING & DIFFERENTIATION OF THE EARTHCONSEQUENCES OF THE HEATING & DIFFERENTIATION OF THE EARTH

1. formation of1. formation ofatmosphereatmosphere (mostly gases from volcanic activity)(mostly gases from volcanic activity)

2. formation of2. formation ofoceansoceans (water released from crystal structure)(water released from crystal structure)

* Life started when atmosphere was modified due to the appearance of the* Life started when atmosphere was modified due to the appearance of the blue-green algae.blue-green algae.

THE EARTHS VITAL STATISTICSTHE EARTHS VITAL STATISTICS

SizeSize

CircumferenceCircumference

first calculated by Eratosthenes first calculated by Eratosthenes

Circumference = 360 degreesCircumference = 360 degrees

800 km800 km 7 degrees7 degreesShapeShape

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Oblate spheroidOblate spheroid

-- flattened at the poles and bulging at the equatorflattened at the poles and bulging at the equator-- Equatorial Radius =Equatorial Radius = 63786378 kmkm-- Polar Radius =Polar Radius = 63576357 kmkm-- Equatorial Circumference =Equatorial Circumference = 4007640076 kmkm-- Polar Circumference =Polar Circumference = 4000840008 kmkm

THE EARTHS LARGE SCALE FEATURESTHE EARTHS LARGE SCALE FEATURES

CONTINENTAL LANDMASSESCONTINENTAL LANDMASSES

1.1. North AmericaNorth America

2.2. South AmericaSouth America

3.3. EuropeEurope

4.4. AsiaAsia

5.5. AntarcticaAntarctica

6.6. AustraliaAustralia

7.7. AfricaAfrica

Prominent Features of ContinentsProminent Features of Continents

1.1. MountainsMountains elevated features of continents elevated features of continents2.2. Mountain RangesMountain Ranges chains of mountains chains of mountains

3.3. Mountain BeltsMountain Belts mountain ranges that runs across a vast area mountain ranges that runs across a vast area

OCEAN BASINS AND GLOBAL OCEANIC RIDGESOCEAN BASINS AND GLOBAL OCEANIC RIDGES

-- Atlantic Ocean, Pacific Ocean, South China Sea, Arctic OceanAtlantic Ocean, Pacific Ocean, South China Sea, Arctic Ocean-- North Atlantic ridges, East Pacific Ridge, Pacific Antarctic Ridge, Southeast Indian Ridge,North Atlantic ridges, East Pacific Ridge, Pacific Antarctic Ridge, Southeast Indian Ridge,

Southwest Indian RidgeSouthwest Indian Ridge

ARCS AND TRENHESARCS AND TRENHES

-- Manila trench, Marianas trenchManila trench, Marianas trenchISOSTASYISOSTASY

-- from a Greek word meaning from a Greek word meaning same standingsame standing-- basically concerned with thebasically concerned with thebuoyancybuoyancy of the blocks of the Earths crust as they rest on theof the blocks of the Earths crust as they rest on the

mantlemantle

-- changes in the load over certain regions causes the lithosphere to make adjustments untilchanges in the load over certain regions causes the lithosphere to make adjustments until isostaticisostaticequilibriumequilibrium (i.e., neither rising or sinking) is reached(i.e., neither rising or sinking) is reached

AIRYS THEORYAIRYS THEORY

Mountains have Mountains have rootsroots which extend down into the mantle. Thus, elevation is proportional to the depth which extend down into the mantle. Thus, elevation is proportional to the depthof the underlying root.of the underlying root.

PRATTS THEORYPRATTS THEORY

Elevation is inversely proportional to density. Thus, the higher the mountain, the lower is its density;Elevation is inversely proportional to density. Thus, the higher the mountain, the lower is its density;

that is, light rocks float higher.that is, light rocks float higher.

ISOSTASY:ISOSTASY:

Airy: mountains have deep rootsAiry: mountains have deep roots

Pratt: mountains are lightPratt: mountains are light

BOTH ARE CORRECT!!!BOTH ARE CORRECT!!!

CONCLUSIONSCONCLUSIONS

The formation of the universe and the solar system is explained by the Big Bang Theory and theThe formation of the universe and the solar system is explained by the Big Bang Theory and the

Nebular Hypothesis, respectively.Nebular Hypothesis, respectively.

The Earth is an oblate spheroid with average radius of 6367 km.The Earth is an oblate spheroid with average radius of 6367 km.

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The Earths large scale features are the continental landmasses and mountain belts, arcs andThe Earths large scale features are the continental landmasses and mountain belts, arcs and

trenches, and ocean basins and ridges.trenches, and ocean basins and ridges.

The Earth is composed of the crust, mantle and core layers.The Earth is composed of the crust, mantle and core layers.

Isostasy determines the elevation to which the landmasses rise.Isostasy determines the elevation to which the landmasses rise.

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LECTURE 3LECTURE 3

MINERALSMINERALS

DEFINITION:DEFINITION: naturally occurring inorganic homogeneous solid that has a definite chemicalnaturally occurring inorganic homogeneous solid that has a definite chemicalcomposition and an ordered internal structurecomposition and an ordered internal structure

PHYSICAL PROPERTIESPHYSICAL PROPERTIES Color caused by the absorption or lack of absorption of various wavelengths of lightColor caused by the absorption or lack of absorption of various wavelengths of light Streak the color of the mineral in powdered form (not necessarily similar to the colorStreak the color of the mineral in powdered form (not necessarily similar to the color

in unpowdered form).in unpowdered form). Hardness the strength of the structure of the mineral relative to the strength of itsHardness the strength of the structure of the mineral relative to the strength of its

chemical bondchemical bondTHE MOHS SCALE OF HARDNESSTHE MOHS SCALE OF HARDNESS

-- TalcTalc 6. Orthoclase6. Orthoclase-- GypsumGypsum 7. Quartz7. Quartz-- CalciteCalcite 8. Topaz8. Topaz-- FluoriteFluorite 9. Corundum9. Corundum-- ApatiteApatite 10. Diamond10. Diamond Crystal form the shapes and aggregates that a certain mineral is likely to formCrystal form the shapes and aggregates that a certain mineral is likely to form

Fibrous, acicular, platy, botryoidalFibrous, acicular, platy, botryoidal Cleavage the tendency of a mineral to break in particular directions due to zones ofCleavage the tendency of a mineral to break in particular directions due to zones of

weakness in the crystal structure (cleavage in 1, 2 and 3 directions)weakness in the crystal structure (cleavage in 1, 2 and 3 directions)Fracture or irregular breakage occur when bond strengths in a crystal structure isFracture or irregular breakage occur when bond strengths in a crystal structure isequal in all directions (e.g. conhoidal fracture)equal in all directions (e.g. conhoidal fracture)

Luster the ability of minerals to reflect lightLuster the ability of minerals to reflect light metallic lustermetallic luster non-metallic lusternon-metallic luster

b.1. earthyb.1. earthyb.2. glassyb.2. glassyb.3. resinousb.3. resinous

Other physical propertiesOther physical properties specific gravityspecific gravity magnetismmagnetism tastetaste reaction to acidreaction to acid fluorescencefluorescence radioactivityradioactivity

THE SILICATE GROUPTHE SILICATE GROUP

-largest group of minerals-largest group of minerals- compounds containing silicon and oxygen- compounds containing silicon and oxygen- building block:- building block: silicon tetrahedron (SiOsilicon tetrahedron (SiO44))-4-4

CLASSIFICATION OF MINERALS BASES OF CLASSIFICATION1. Silicates 1. Composition2. Non-silicates 2. Crystal structure

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Relative Abundance of the Most Common Elements in the CrustRelative Abundance of the Most Common Elements in the Crust

THE SILICATESTHE SILICATES

1.5all others

2.1magnesium, Mg

2.6potassium, K

2.8sodium, Na

3.6calcium, Ca

5iron, Fe

8.1aluminum, Al

27.7silicon, Si

46.6oxygen, O

APPROXIMATE PERCENTAGEBY WEIGHT

ELEMENT

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TTHE NON-SILICATE GROUPSHE NON-SILICATE GROUPS

THE MOST COMMON ROCK FORMING MINERALSTHE MOST COMMON ROCK FORMING MINERALS

-- FELDSPARFELDSPAR-- QUARTZQUARTZ-- OLIVINEOLIVINE-- PYROXENEPYROXENE

-- AMPHIBOLEAMPHIBOLE-- MICAMICA-- CLAYCLAY-- CALCITECALCITE

ConclusionsConclusions

Minerals exhibit a variety of physical and chemical properties that result from theirMinerals exhibit a variety of physical and chemical properties that result from their

chemical compositions and atomic structures.chemical compositions and atomic structures.

A number of special physical and chemical properties are useful in identifying particularA number of special physical and chemical properties are useful in identifying particular

minerals.minerals.

3. The two major mineral groups are Silicates and Non-Silicate groups, where the former is3. The two major mineral groups are Silicates and Non-Silicate groups, where the former is

more common than the latter.more common than the latter.4. The most common rock forming minerals are feldspar, quartz,olivine, pyroxene,4. The most common rock forming minerals are feldspar, quartz,olivine, pyroxene,

amphibole,amphibole,

mica, clay and calcite.mica, clay and calcite.

5. Minerals are non-renewable resources.5. Minerals are non-renewable resources.

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LECTURE 4LECTURE 4IGNEOUS ROCKSIGNEOUS ROCKS

What is a rock?What is a rock?

Solid material composed ofSolid material composed of

mineralsminerals

glassglass

organic matterorganic matter

pre-existing rockspre-existing rocks

THE ROCK CYCLETHE ROCK CYCLE

Igneous rocksIgneous rocksrocks formed fromrocks formed from

molten material called magma or lavamolten material called magma or lava

OROR

deposits/debris of volcanic eruptionsdeposits/debris of volcanic eruptions

MagmaMagma

Molten rock composed of varying amounts ofMolten rock composed of varying amounts of

LiquidLiquid

Silicate (sometimes carbonate or sulfide)Silicate (sometimes carbonate or sulfide)

Ions of K, Na, Fe, Ca, Mg, AlIons of K, Na, Fe, Ca, Mg, Al

SolidSolid

MineralsMineralsRock fragmentsRock fragments

Dissolved gasDissolved gas

HH22O, COO, CO22, SO, SO22

Temperature: 600-1200Temperature: 600-1200oo

CC

Classification (cheml composition)Classification (cheml composition)

Felsic, Silicic orFelsic, Silicic oracidicacidic

-- >63% SiO>63% SiO22

Intermediate - 52-63% SiOIntermediate - 52-63% SiO22

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Mafic orMafic orbasic-basic- 45-52% SiO45-52% SiO22

Ultramafic orUltramafic orultrabasicultrabasic -

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SizeSize

Coarse-grainedCoarse-grained

Mineral grains visible to naked eyeMineral grains visible to naked eye

PhaneriticPhaneriticFine grainedFine grained

Mineral grains not visible to naked eyeMineral grains not visible to naked eye

AphaniticAphanitic

Coarse- and fine-grainedCoarse- and fine-grained

Visible mineral grains (phenocrysts) surrounded by glass or fine mineral grains (groundmass)Visible mineral grains (phenocrysts) surrounded by glass or fine mineral grains (groundmass)

PorphyriticPorphyritic

CrystallinityCrystallinity

Crystalline all are mineral grainsCrystalline all are mineral grains

Glassy no minerals, all glassGlassy no minerals, all glassHypocrystalline mineral grains in glassy groundmassHypocrystalline mineral grains in glassy groundmass

Other texturesOther textures

Vesicular has holes /Vesicular has holes / vesiclesvesicles

Pyroclastic made up of fragmented grainsPyroclastic made up of fragmented grains

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Origin of texturesOrigin of textures

Cooling historyCooling history

Slow cooling: coarse crystalsSlow cooling: coarse crystals

Fast cooling: fine crystalsFast cooling: fine crystals

Very fast cooling: glassVery fast cooling: glass

Degassing processesDegassing processes

Exsolution of gases produce vesiclesExsolution of gases produce vesicles

Explosive eruptions produce fragmental (pyroclastic) textureExplosive eruptions produce fragmental (pyroclastic) texture

Interpretation of texturesInterpretation of textures

Phaneritic formation below surface at slow cooling ratesPhaneritic formation below surface at slow cooling rates

Aphanitic, glassy formation at surface with fast to very fast cooling ratesAphanitic, glassy formation at surface with fast to very fast cooling rates

Porphyritic formed by slow, then fast cooling ratesPorphyritic formed by slow, then fast cooling rates

Vesicular non-violent degassingVesicular non-violent degassing

Pyroclastic violent, explosive eruptionPyroclastic violent, explosive eruption

Classification of Igneous RocksClassification of Igneous Rocks

Texture + Composition (color index)Texture + Composition (color index)

texturetexture felsicfelsic intermediateintermediate maficmafic ultramaficultramafic

phaneriticphaneritic granitegranite dioritediorite gabbrogabbro PeridotitePeridotite

Porphyritic/aphaniticPorphyritic/aphanitic rhyoliterhyolite andesiteandesite basaltbasalt

VesicularVesicular pumicepumice pumicepumice scoriascoriaglassyglassy obsidianobsidian

fragmentalfragmental Agglomerate, volcanic breccia, lapilli stone, tuffAgglomerate, volcanic breccia, lapilli stone, tuff

Landforms and other associated features in a volcanic environmentLandforms and other associated features in a volcanic environment

dikesdikes

sillsill

batholithbatholith

lopolith/laccolithlopolith/laccolith

xenolithxenolith

stockstock

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LECTURE 5LECTURE 5

VOLCANISMVOLCANISM

What is a volcano?What is a volcano?From wordFrom word Vulcan,Vulcan, Roman god of fire and metal workingRoman god of fire and metal working

Geologic landform where molten rocks from the planets interior are ejected toGeologic landform where molten rocks from the planets interior are ejected to

the surfacethe surface

Generic Volcano FeaturesGeneric Volcano Features

Central VentCentral VentSummit CraterSummit CraterEdificeEdifice

Magma ChamberMagma Chamber

Parasitic ConesParasitic Cones

FumarolesFumaroles

How do we know if a volcano is active?How do we know if a volcano is active?

Active erupted during the last 10,000 yrs.Active erupted during the last 10,000 yrs.- Inactive no activity during the last 10,000 yrs.- Inactive no activity during the last 10,000 yrs.

- Potentially active - volcanic activit between 10 ka 1.65 Ma- Potentially active - volcanic activit between 10 ka 1.65 Ma

Types of volcanoesTypes of volcanoes0.0. Based on morphology and building materialsBased on morphology and building materials

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Where can we find volcanoes?Where can we find volcanoes?

Boundaries of lithospheric platesBoundaries of lithospheric plates

Middle of plates: Hot spotsMiddle of plates: Hot spotsWhat is a volcanic eruption?What is a volcanic eruption?

ejection ofejection of molten rockmolten rock

fragmented rocks and ash AND/ORfragmented rocks and ash AND/OR

gasesgases

caused bycaused by influx of magma from deeper sourceinflux of magma from deeper source

melting of underlying rocksmelting of underlying rocks

exsolution of gasesexsolution of gases

accompanied byaccompanied by earthquakesearthquakes

ground deformationground deformation

Characterizing eruptionsCharacterizing eruptions

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Types of volcanic eruptionTypes of volcanic eruption

Hawaiian and StrombolianHawaiian and Strombolian

Hawaiian -lava fountains and flowsHawaiian -lava fountains and flowsStrombolian - intermittent ejection of partiallyStrombolian - intermittent ejection of partially

molten rocksmolten rocks

Peleean (Nue Ardente)Peleean (Nue Ardente)large quantity of volcanic materials blown out of alarge quantity of volcanic materials blown out of a

central crater, fall back, and form tongue-central crater, fall back, and form tongue-like, glowing avalancheslike, glowing avalanches

VulcanianVulcanian

-Discrete ejection of mostly solid materials and-Discrete ejection of mostly solid materials andgases from more viscous magmasgases from more viscous magmas

PlinianPlinian

Sustained eruption of large amounts ofSustained eruption of large amounts ofpyroclastic materials and gasespyroclastic materials and gases

Produces high eruption columnsProduces high eruption columns

Phreatomagmatic / PhreaticPhreatomagmatic / Phreatic

PhreatomagmaticPhreatomagmatic-contact between magma and surface/ground-contact between magma and surface/ground

waterwater

PhreaticPhreatic- caused by vaporization of surface/ground- caused by vaporization of surface/ground

waterswaters

--no magma-water contactno magma-water contact

What hazards do volcanoes pose?What hazards do volcanoes pose?

What can we get from volcanoes?What can we get from volcanoes?Geothermal EnergyGeothermal Energy

Energy derived from heat within the earthEnergy derived from heat within the earthPhilippine geothermal energyPhilippine geothermal energy

How many volcanoes are there in the Philippines? What are their characteristics?How many volcanoes are there in the Philippines? What are their characteristics?

22 active volcanoes and more than 200 inactive22 active volcanoes and more than 200 inactive most active is Mayon Volcano with 47 historical eruptionsmost active is Mayon Volcano with 47 historical eruptions

7 active volcanoes are being monitored by PHIVOLCS7 active volcanoes are being monitored by PHIVOLCS

Eruption column/cloud

materials ejected into the air

Blocks and bombs Lapilli ash

Danger to aviation Collapse of roofs

Lava flows stream of molten rock

Destruction in direct path

Contact with water (explosive)Types of Lava Flows

A'a lava surfaces are fragmented, rough, andspinyPahoehoe Lava surfaces are smooth, billowy orropy.

Gas

HCl, HF, H2S, H2SO4 Climatic effects Acid rain suffocation

Pyroclastic flows

mixture of hot particles and gases flow downslope at HIGH speed greatest hazard

Lahars

Pyroclastic materials remobilized by waterDebris avalanche

Caused by collapse of part of the volcanicedifice

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LLECTURE 6ECTURE 6

SEDIMENTARY ROCKSSEDIMENTARY ROCKS

Steps in forming Sedimentary Rocks:Steps in forming Sedimentary Rocks:

1. WEATHERING1. WEATHERING

thethe chemicalchemical alteration,alteration, physicalphysical, and, and biologicalbiological breakdown of rocks during exposure to thebreakdown of rocks during exposure to the

atmosphere, hydrosphere, and biosphereatmosphere, hydrosphere, and biosphere-two types of weathering:-two types of weathering:

(1)(1) mechanical/physicalmechanical/physical-requires the application of some physical force or stress to be applied to the rock-requires the application of some physical force or stress to be applied to the rock --

- no accompanying changes to the composition of rocks- no accompanying changes to the composition of rocks

mechanical breakup increases the rocksmechanical breakup increases the rocks surface areasurface area and the surface-to-volume ratioand the surface-to-volume ratio

some mechanical weathering processessome mechanical weathering processes

1)1) Freezing and thawingFreezing and thawing- The expansion force of water as it freezes is sufficient to split any mineral or- The expansion force of water as it freezes is sufficient to split any mineral orrock.rock.

2)2) Heating and coolingHeating and cooling - Differences in temperature in a rock give rise to differential expansion and- Differences in temperature in a rock give rise to differential expansion and

contraction.contraction.

3)3) Wetting and dryingWetting and drying- The disruption of soil results in the swelling and contracting of soil peds and- The disruption of soil results in the swelling and contracting of soil peds and

particles.particles.4)4) Grinding or rubbingGrinding or rubbing- Grinding action, or the rubbing of moving rock against each other.- Grinding action, or the rubbing of moving rock against each other. 5)5) OrganismsOrganisms- Action of organisms, including animals and plants reduces the size of rocks and- Action of organisms, including animals and plants reduces the size of rocks and

minerals.minerals.

6)6) UnloadingUnloading - the removal sediments overlying deeply buried rocks by erosion or uplift, results in the- the removal sediments overlying deeply buried rocks by erosion or uplift, results in the

exfoliation of rocksexfoliation of rocks(2)(2) chemicalchemical

- breakdown of minerals by chemical reactions with water, with chemicals dissolved in water, or- breakdown of minerals by chemical reactions with water, with chemicals dissolved in water, or

with gases in the airwith gases in the air progression from less stable minerals to more stable mineralsprogression from less stable minerals to more stable minerals

Some chemical weathering processesSome chemical weathering processes1)1) DissolutionDissolution- the dissolving of a solid in a liquid- the dissolving of a solid in a liquid2)2) HydrolysisHydrolysis - process of minerals reacting with water to form hydroxides, which usually are more- process of minerals reacting with water to form hydroxides, which usually are moresoluble than the original mineral. example - pyroxene to Fe oxide 4FeSiO3 + H2O + O2 -->4FeO(OH)soluble than the original mineral. example - pyroxene to Fe oxide 4FeSiO3 + H2O + O2 -->4FeO(OH)

+ 4SiO2+ 4SiO2

3)3) AcidificationAcidification - Weathering is accelerated by the presence of the hydrogen ion in water, such as- Weathering is accelerated by the presence of the hydrogen ion in water, such as

that provided by carbonic and organic acids.that provided by carbonic and organic acids.4)4) HydrationHydration - combination of a solid mineral or element with water.- combination of a solid mineral or element with water.

5)5) Oxidation andOxidation and ReductionReduction - used in mineral weathering, is both the chemical combination of- used in mineral weathering, is both the chemical combination of

oxygen with a compound and the change in oxidation number of some chemical elementoxygen with a compound and the change in oxidation number of some chemical element

(Reduction is the chemical process in which electrons are gained.)(Reduction is the chemical process in which electrons are gained.)66) Ion-exchange -) Ion-exchange - involves the transfer of charged atoms (ions) of calcium, magnesium, sodium, andinvolves the transfer of charged atoms (ions) of calcium, magnesium, sodium, and

potassium between waters rich in one of the ions and a mineral rich in anotherpotassium between waters rich in one of the ions and a mineral rich in another(Most effective in clays.)(Most effective in clays.) ExamplesExamples

Some chemical weathering reactionsSome chemical weathering reactionsSolution of calcite (no solid residue)Solution of calcite (no solid residue)

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ClimateClimate

Temperature fluctuations determine importance of ice-wedging and insulationTemperature fluctuations determine importance of ice-wedging and insulation

Precipitation governs the extent of hydrolysis, hydration and solutionPrecipitation governs the extent of hydrolysis, hydration and solutionTopographic ReliefTopographic Relief

influence the amount of rock exposed to the forces of weatheringinfluence the amount of rock exposed to the forces of weathering

Slope steepness controls the rate at which weathering products are eroded to be transportedSlope steepness controls the rate at which weathering products are eroded to be transported

elsewhereelsewhere

2. EROSION2. EROSIONcomes from old word meaning eat awaycomes from old word meaning eat away

involves movement or rock an soilinvolves movement or rock an soil

Agents of Erosion:Agents of Erosion:

gravitygravityiceice

organismorganism

waterwater

windwindSome types of erosion processesSome types of erosion processes

SlumpSlump

Rock and debris slideRock and debris slide

Rock and debris fallRock and debris fall

3. TRANSPORTATION3. TRANSPORTATION

Agents of sediment transport:Agents of sediment transport:

iceicewaterwater

WindWind

Distance of sediment transport affects clast:Distance of sediment transport affects clast:

Roundness -Roundness - measures how rounded clasts corners aremeasures how rounded clasts corners are

SpherecitySpherecity-- measures sphere-like shape of clastsmeasures sphere-like shape of clasts

Sorting -Sorting - Measure of variation of grain sizeMeasure of variation of grain size

4. DEPOSITION4. DEPOSITIONTransporting sediment requires energyTransporting sediment requires energy

Grain size has relationship with energyGrain size has relationship with energy

Smaller grains take less energySmaller grains take less energy

Bigger grains take moreBigger grains take moreIf river slows down, sediment will drop outIf river slows down, sediment will drop out

If river speeds up, water can pick up sedimentIf river speeds up, water can pick up sediment

Larger sediments are deposited in higher energy environmentsLarger sediments are deposited in higher energy environments

Examples:Examples:Gravel - needs fast moving water or rock slidesGravel - needs fast moving water or rock slides

Sand - wind and wave action (beaches)Sand - wind and wave action (beaches)Silt and Clay - lakes, swamps and deep oceansSilt and Clay - lakes, swamps and deep oceans

5. DIAGENESIS5. DIAGENESIS

physical, chemical, and biological processes which collectively result inphysical, chemical, and biological processes which collectively result in transformation of sediments into sedimentarytransformation of sediments into sedimentary

rockrock

modification of the texture and mineralogy ofmodification of the texture and mineralogy of

the rockthe rock Stages of diagenesis are:Stages of diagenesis are:

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Early diagenesisEarly diagenesis

takes place from sedimentation until shallowtakes place from sedimentation until shallow

burialburial

Late diagenesisLate diagenesis from deep burial to subsequent upliftfrom deep burial to subsequent uplift

Factors that affect diagenesis are:Factors that affect diagenesis are:

pHpH

Eh-redox potentialEh-redox potential-- pressure-- pressure

temperaturetemperature concentration of anions and cationsconcentration of anions and cations

depth of burialdepth of burial

The different types of Diagenetic ProcessesThe different types of Diagenetic Processes

areare::

CompactionCompaction

RecrystallizationRecrystallization Pressure dissolutionPressure dissolution

CementationCementation

AuthigenesisAuthigenesis

ReplacementReplacement BioturbationBioturbation

The simple ideal model for the evolution of sedimentary rocks says there are three basic end products,The simple ideal model for the evolution of sedimentary rocks says there are three basic end products, that all sedimentary processes are working to reach - quartz sandstone, shale, and limestone.that all sedimentary processes are working to reach - quartz sandstone, shale, and limestone. The three end products in the simple ideal model are not isolated, each one stands for a class ofThe three end products in the simple ideal model are not isolated, each one stands for a class of

weathering products.weathering products.

Quartz sandstoneQuartz sandstone == all visible grainsall visible grains, including such ones as incompletely weathered feldspar, including such ones as incompletely weathered feldspar

from the granodiorite in the simple ideal model.from the granodiorite in the simple ideal model.

ShaleShale == all clay sized grainsall clay sized grains (clay is a generic name; there are many kinds of clay minerals as well(clay is a generic name; there are many kinds of clay minerals as well

as other minerals that are clay sized)as other minerals that are clay sized) LimestoneLimestone == all dissolved mineralsall dissolved minerals, including not only calcite CaCO, including not only calcite CaCO33, but also halite (table salt;, but also halite (table salt;

NaCl), and gypsum (CaSONaCl), and gypsum (CaSO44 . H. H22O) among others.O) among others.

Sedimentary rocks are generally divided into three great categories:Sedimentary rocks are generally divided into three great categories:

1. SILISICLASTIC (or simply, clastic) rocks1. SILISICLASTIC (or simply, clastic) rocks

Clastic rocks (sandstones, shales, etc.) are classified on two criteria -Clastic rocks (sandstones, shales, etc.) are classified on two criteria - texturetexture (grain size), and(grain size), and

compositioncomposition (that is,(that is, QFLQFL).).

Clastic particles are divided into size categories based on theClastic particles are divided into size categories based on the WENTWORTH SCALEWENTWORTH SCALE. This scale has. This scale hasbeen in use for over a hundred years and is universally recognized.been in use for over a hundred years and is universally recognized.

The Wentworth scale is straight forward, and with a ruler for scale it is relatively easy to classify theThe Wentworth scale is straight forward, and with a ruler for scale it is relatively easy to classify the

rock.rock.

They have a clastic (broken or fragmental) texture consisting of:They have a clastic (broken or fragmental) texture consisting of: ClastClast (larger pieces, such as sand or gravel)(larger pieces, such as sand or gravel)

MatrixMatrix (mud or fine-grained sediment surrounding the clasts)(mud or fine-grained sediment surrounding the clasts)

CementCement (the glue that holds it all together, such as:(the glue that holds it all together, such as:

calcite, iron oxide, or silicacalcite, iron oxide, or silica

Examples:Examples:

Breccia - Grain size = 2 cm or greaterBreccia - Grain size = 2 cm or greater- Clasts are angular- Clasts are angular

Conglomerate - Grain size = 2 cm or greaterConglomerate - Grain size = 2 cm or greater

- Clasts are rounded- Clasts are rounded

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Siltstone - Grain size = 1/256 to 1/16 mmSiltstone - Grain size = 1/256 to 1/16 mm

- gritty texture- gritty texture

Shale - Grain size = less than 1/256 mmShale - Grain size = less than 1/256 mmSandstone - Grain size = 1/16 mm to 2 mmSandstone - Grain size = 1/16 mm to 2 mm

- classified according to the amount of minerals found in the rock- classified according to the amount of minerals found in the rock

Arkose Sandstone - 75% greaterArkose Sandstone - 75% greater

feldsparfeldspar

Quartz Sandstone - 95% or greaterQuartz Sandstone - 95% or greaterquartz contentquartz content

Lithic SandstoneLithic Sandstone

2. CHEMICAL AND 3. BIOCHEMICAL ROCKS2. CHEMICAL AND 3. BIOCHEMICAL ROCKS

chemical rockschemical rocksCARBONATESCARBONATES composed of the mineral calcite (CaCOcomposed of the mineral calcite (CaCO33 - calcium carbonate)- calcium carbonate)

they form by both chemical and biochemical processesthey form by both chemical and biochemical processes

tend to be mixed together in various combinations in the rocks.tend to be mixed together in various combinations in the rocks.

They are extremely abundant and important.They are extremely abundant and important.

OTHER CHEMICAL ROCKSOTHER CHEMICAL ROCKS These rocks fall into two categoriesThese rocks fall into two categories

ChertChert a siliceous rock (composed of SiOa siliceous rock (composed of SiO22))

forms from the recrystalized skeletons of " animals " (single celled radiolarians, and glass sponges) orforms from the recrystalized skeletons of " animals " (single celled radiolarians, and glass sponges) orsingle celled " plants " (diatoms, silicoflagellates).single celled " plants " (diatoms, silicoflagellates).

Rock saltRock salt (halite; NaCl) and(halite; NaCl) and gypsumgypsum (CaSO(CaSO44 . H. H22O)O)

originally are dissolved in the sea water, thus making the sea salty.originally are dissolved in the sea water, thus making the sea salty.

sea water evaporates in a closed area, such as a lagoon, the salt concentration becomes very high,sea water evaporates in a closed area, such as a lagoon, the salt concentration becomes very high,supersaturated, and precipitates out.supersaturated, and precipitates out.

The process is common in desert areas, with examples today in the Red Sea and Dead Sea in theThe process is common in desert areas, with examples today in the Red Sea and Dead Sea in the

Middle East, both highly saline.Middle East, both highly saline.

OTHER BIOCHEMICAL ROCKSOTHER BIOCHEMICAL ROCKS

PeatPeat andand coalcoal come from plant remains are biochemical rockscome from plant remains are biochemical rocks

always form in the presence of clastic rocks - sandstones and shales.always form in the presence of clastic rocks - sandstones and shales.

The different types of coal are:The different types of coal are:

AnthraciteAnthracite coal with the highest carbon content, between 86 and 98 percentcoal with the highest carbon content, between 86 and 98 percent

heat value of nearly 15,000 BTUs-per-pound.heat value of nearly 15,000 BTUs-per-pound.

BituminousBituminous

used primarily to generate electricity and make coke for the steel industry.used primarily to generate electricity and make coke for the steel industry. has a carbon content ranging from 45 to 86 percent carbon and a heat value of 10,500 to 15,500has a carbon content ranging from 45 to 86 percent carbon and a heat value of 10,500 to 15,500

BTUs-per-pound.BTUs-per-pound.

SubbituminousSubbituminous Ranking below bituminous with 35-45 percent carbon contentRanking below bituminous with 35-45 percent carbon content

a heat value between 8,300 and 13,000 BTUs-per-pound.a heat value between 8,300 and 13,000 BTUs-per-pound.

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this coal generally has a lower sulfur content than other types, which makes it attractive for usethis coal generally has a lower sulfur content than other types, which makes it attractive for use

because it is cleaner burning.because it is cleaner burning.

LigniteLignite

geologically young coal which has the lowest carbon content, 25-35 percentgeologically young coal which has the lowest carbon content, 25-35 percent heat value ranging between 4,000 and 8,300 BTUs-per-pound.heat value ranging between 4,000 and 8,300 BTUs-per-pound.

Sometimes called brown coal, mainly used for electric power generation.Sometimes called brown coal, mainly used for electric power generation.

Some common sedimentary structuresSome common sedimentary structures

MudcracksMudcracksFlutesFlutes

Cross-beddingCross-beddingRipple marksRipple marks

TrailsTrails

Escape trailsEscape trails

StromatolitesStromatolitesBurrow castBurrow castUses of Carbonate RocksUses of Carbonate Rocks

LimewaterLimewatera substance derived from limestone is used to produce paper and is also used as a bulkinga substance derived from limestone is used to produce paper and is also used as a bulkingagent to use less trees in the production of paperagent to use less trees in the production of paper Glass is mostly made from sand, but limestone is also added to it before it is heated upGlass is mostly made from sand, but limestone is also added to it before it is heated up

Limestone is also used in the production of steel where it mixes with iron impurities and becomes aLimestone is also used in the production of steel where it mixes with iron impurities and becomes a

slag which is removed from pure molten ironslag which is removed from pure molten iron

Clay and limestone when mixed and heated together forms cement which is used for constructionClay and limestone when mixed and heated together forms cement which is used for construction LimestoneLimestone has been used as building material for many centuries. Many of the pyramids were builthas been used as building material for many centuries. Many of the pyramids were built

with a number of different stone materials.with a number of different stone materials.

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Lecture 7Lecture 7

Sedimentary EnvironmentsSedimentary Environments

A part of the earths surface, physically, chemically, and biologically distinct from adjacent terrain.A part of the earths surface, physically, chemically, and biologically distinct from adjacent terrain.

defined by, fauna and flora, geology, geomorphology, climate, weather, temperature, and if sub-aqueous, thedefined by, fauna and flora, geology, geomorphology, climate, weather, temperature, and if sub-aqueous, thedepth, salinity, and current system of the water.depth, salinity, and current system of the water.

could be a site of erosion, non-deposition, or deposition.could be a site of erosion, non-deposition, or deposition.

Erosional environments - occur in dissected mountain chains and rocky shores.Erosional environments - occur in dissected mountain chains and rocky shores.

Equilibria/non-depositional environments - occur both on land and under the sea, commonly preserved in theEquilibria/non-depositional environments - occur both on land and under the sea, commonly preserved in the

stratigraphic recordsstratigraphic records as unconformities.as unconformities.

Continental

Alluvial fanFluviatileLacustrineEolian

BraidedMeandering

Transitional(Shorelines)

Lobate (deltas)Linear

TerrigenousMixed carbonate: terrigenousCarbonate

Marine

ReefShelfSubmarine channel and fanPelagic

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cone-shaped typically found in tectonically active regions (rifting continental grabens and foreland basins)

What is an alluvial fan?

non-marine sedimentary body a fan-shaped deposita fan-shaped deposit

How it is formed?How it is formed?When mountains shed sediment off their flanks, streams carry it away as alluvium.When mountains shed sediment off their flanks, streams carry it away as alluvium.

A mountain stream carries lots of alluvial sediment easily when its gradient is steep and energy is abundant.A mountain stream carries lots of alluvial sediment easily when its gradient is steep and energy is abundant.

Where are alluvial fans found?Where are alluvial fans found?

They can be found in places where the stream or mass-flow emerges from a valley into a basin.They can be found in places where the stream or mass-flow emerges from a valley into a basin.

Fluvial EnvironmentFluvial EnvironmentThree ways streams transport sediments:Three ways streams transport sediments:

in solution (dissolved load)in solution (dissolved load)

in suspension (suspended load)in suspension (suspended load)

along the bottom of the channel (bedload)along the bottom of the channel (bedload)

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Type and amount of material in suspension isType and amount of material in suspension iscontrolled by:controlled by: water velocitywater velocity

settling velocity of each grainsettling velocity of each grain

Factors affecting settling velocityFactors affecting settling velocity sizesize shapeshape

specific gravityspecific gravitybedloadbedloadcomposed of coarser particles - cannot be carried by suspensioncomposed of coarser particles - cannot be carried by suspension

bedload particles move along by:bedload particles move along by:

rollingrolling slidingsliding

saltationsaltation

Ability of streams to carry sediments is describedAbility of streams to carry sediments is described

by:by: capacity - maximum load of sediment that a stream can transportcapacity - maximum load of sediment that a stream can transport competence - measure of the maximum size of particles it is capable of transportingcompetence - measure of the maximum size of particles it is capable of transporting

A longitudinal profile can be divided in threeA longitudinal profile can be divided in threeparts:parts:-drainage system (tributary, head)-drainage system (tributary, head)

-transport system-transport system

-distributary system (mouth)-distributary system (mouth)

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Meandering SystemMeandering System consist of one single channel and thalwegconsist of one single channel and thalweg low gradient and high sinuositylow gradient and high sinuosity

sediments deposited at the inner sides of meander bendssediments deposited at the inner sides of meander bends

associated with vegetated areas under a humid climateassociated with vegetated areas under a humid climate deposition of sediments takes place in the channel, on the levees and in the basins.deposition of sediments takes place in the channel, on the levees and in the basins.

gravel and coarse sand are normally found on the channel floor (`gravel and coarse sand are normally found on the channel floor (` lag deposits'lag deposits').).

finer sand settles along the inner bends of the river, on so-called `finer sand settles along the inner bends of the river, on so-called `point bars'point bars'..

Evolution of an Oxbow lakeEvolution of an Oxbow lake(1) On the inside of the loop, the river travels more slowly leading to deposition of silt.(1) On the inside of the loop, the river travels more slowly leading to deposition of silt. (2) Meanwhile water on the outside edges tends to flow faster, which erodes the banks making the meander(2) Meanwhile water on the outside edges tends to flow faster, which erodes the banks making the meandereven wider.even wider.(3) Over time the loop of the meander widens until the neck vanishes altogether.(3) Over time the loop of the meander widens until the neck vanishes altogether.(4) Then the meander is removed from the river's current and the horseshoe shaped oxbow lake is formed.(4) Then the meander is removed from the river's current and the horseshoe shaped oxbow lake is formed.

Without a current to move the water along, sediment builds up along the banks and fills in the lake.Without a current to move the water along, sediment builds up along the banks and fills in the lake.

Braided SystemBraided System have one single channel of low sinuosity and high gradient, with multiple `thalwegs' and bars.have one single channel of low sinuosity and high gradient, with multiple `thalwegs' and bars. high sediment loadhigh sediment load During times of maximum discharge, the channel is completely inundatedDuring times of maximum discharge, the channel is completely inundated

In times of low discharge, multiple thalwegs and bars reappear within the channelIn times of low discharge, multiple thalwegs and bars reappear within the channel

occur in areas with a highly irregular water regime, and abundant sediment supplyoccur in areas with a highly irregular water regime, and abundant sediment supply Deposits contain alternating areas (lenses) of coarse gravel and sandDeposits contain alternating areas (lenses) of coarse gravel and sand

Drainage patternsDrainage patterns

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1. Dendritic1. Dendritic

-Uniform underlying bedrock-Uniform underlying bedrock--

Igneous rocksIgneous rocks

--

Flat-lying sedimentary rocksFlat-lying sedimentary rocks--

Most common drainage pattern on all scales.Most common drainage pattern on all scales.

--Determined by direction of slope of landDetermined by direction of slope of land2.Radial2.Radial

-Develops in isolated volcanic cones and domal uplifts-Develops in isolated volcanic cones and domal uplifts

--

Often localizedOften localized3.Rectangular3.Rectangular

-Common in faulted or fractured igneous rock-Common in faulted or fractured igneous rock

--

Often control pattern of streamsOften control pattern of streams-Guides directions of valleys-Guides directions of valleys

-E.g. Shell Falls, Wyoming.-E.g. Shell Falls, Wyoming.

4.Trellis4.Trellis

-Most common in tilted and folded sedimentary or ----Most common in tilted and folded sedimentary or ---metamorphic rocksmetamorphic rocks

--

Formed by alternating less resistant and resistant lFormed by alternating less resistant and resistant llayers.layers.

- e.g. Appalachians- e.g. Appalachians

Lacustrine EnvironmentLacustrine Environment lakelake --landlocked body of standing, non-marine waterlandlocked body of standing, non-marine water

Tectonic setting - found in fault grabens or basins with internal drainage or limited flowTectonic setting - found in fault grabens or basins with internal drainage or limited flow

Geometry - circular or elongate in plan view; lenticular in cross sectionGeometry - circular or elongate in plan view; lenticular in cross section Typical sequence - coarsening upward from laminated shales, marls, and limestones to crossbeds ofTypical sequence - coarsening upward from laminated shales, marls, and limestones to crossbeds ofsandstonessandstones

There are several ways in which lakes are formed. These are the most common lakes you may encounter:There are several ways in which lakes are formed. These are the most common lakes you may encounter:

Glacial Lakes -Glacial Lakes -

occur where basins have been excavated by moving ice or where drainage patterns have been altered byoccur where basins have been excavated by moving ice or where drainage patterns have been altered by

deposition of glacial till.deposition of glacial till.

Oxbow Lakes-Oxbow Lakes-

formed when river meanders are cut off from the main channel and are therefore generally found in theformed when river meanders are cut off from the main channel and are therefore generally found in theimmediate vicinity of rivers.immediate vicinity of rivers.

Levee Lakes-Levee Lakes-formed when the water levels of rivers become too high and deposits enough sediment to form a completelyformed when the water levels of rivers become too high and deposits enough sediment to form a completely

separate water body. Levees may also be man-made.separate water body. Levees may also be man-made. Barrier Lakes-Barrier Lakes-occur behind sand bars in coastal regions and have characteristically high levels of salinity. Water of this type, aoccur behind sand bars in coastal regions and have characteristically high levels of salinity. Water of this type, a

mixture of fresh and salt waters, is referred to as brackish water.mixture of fresh and salt waters, is referred to as brackish water.

Eolian EnvironmentEolian Environment windwind

a turbulent stream of aira turbulent stream of air like water, it has the ability to erode, transport and depositlike water, it has the ability to erode, transport and deposit

two properties:two properties:

low density - limits competencelow density - limits competence

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unrestricted flow - enables spread over wide areas and high atmosphereunrestricted flow - enables spread over wide areas and high atmosphere

lack of rain allows more effective wind worklack of rain allows more effective wind workdesertsdeserts (arid environment)(arid environment)

eolianeolian (from Aeolus, Greek god of winds) - describes activity of deposits of winds(from Aeolus, Greek god of winds) - describes activity of deposits of winds

Sand TransportSand Transport

Creep -Creep - large particles are rolled to the surface after coming into contact with saltating particles.large particles are rolled to the surface after coming into contact with saltating particles.SaltationSaltation - bouncing and jumping movement of grains. Involves bedload.- bouncing and jumping movement of grains. Involves bedload.

Suspension -Suspension - occurs when fine dust and dirt are lifted into the wind. Involves suspended load.occurs when fine dust and dirt are lifted into the wind. Involves suspended load.

Wind ErosionWind Erosion needs chemical and mechanical weathering to act effectivelyneeds chemical and mechanical weathering to act effectively two types of wind erosion:two types of wind erosion:

abrasionabrasion

deflation - erosion of ground when dry, loose particles of dust and salt are lifted and blown awaydeflation - erosion of ground when dry, loose particles of dust and salt are lifted and blown away (formation(formation

of a desert pavement)of a desert pavement)SandblastingSandblasting

shaping of solid rock surfaces by constant impact of grains by windshaping of solid rock surfaces by constant impact of grains by wind (e.g. Ventifacts - shaped by the wind)(e.g. Ventifacts - shaped by the wind)

DesertsDeserts

concentrated in two regions:concentrated in two regions:subtropicssubtropics

middle-latitudesmiddle-latitudes

areas where rainfall is less than 250 mm (10 in.)/year, or where evaporation exceeds precipitation.areas where rainfall is less than 250 mm (10 in.)/year, or where evaporation exceeds precipitation. Rainfall in deserts may vary from 0.2 cm./yr. to about 40 cm./yr. Rainfalls of 5-20 cm./yr. are common.Rainfall in deserts may vary from 0.2 cm./yr. to about 40 cm./yr. Rainfalls of 5-20 cm./yr. are common.

Temperature extremes can vary from 60 degrees F. in Mongolian deserts to 137 degrees F. in the SaharaTemperature extremes can vary from 60 degrees F. in Mongolian deserts to 137 degrees F. in the Sahara

Desert. Temperatures in excess of 180 degrees may occur in sands exposed to full solar radiation.Desert. Temperatures in excess of 180 degrees may occur in sands exposed to full solar radiation. Great daily extremes can occur.Great daily extremes can occur. Due to lack of vegetation, wind velocities are high.Due to lack of vegetation, wind velocities are high.

Causes of DesertsCauses of Deserts caused by high mountains causing available moisture to condense and precipitate on their higher parts,caused by high mountains causing available moisture to condense and precipitate on their higher parts,reducing moisture available for lowlands in the lee of mountains.reducing moisture available for lowlands in the lee of mountains.

Direct blocking of moisture may also occur.Direct blocking of moisture may also occur.

Wind DepositsWind Deposits

deflation lag depositsdeflation lag deposits - Coarsest clasts (desert pavement)- Coarsest clasts (desert pavement) loessloess - Unconsolidated, unstratified aggregation of small, angular mineral fragments, usually buff in color.- Unconsolidated, unstratified aggregation of small, angular mineral fragments, usually buff in color.Generally believed to be wind-deposited.Generally believed to be wind-deposited.

dunesdunes - Sand dunes form when there is (1) a ready supply of sand, (2) a steady wind, and (3) some kind of- Sand dunes form when there is (1) a ready supply of sand, (2) a steady wind, and (3) some kind of

obstacle such as vegetation, rocks, or fences, to trap some of the sand. Sand dunes form when moving air slowsobstacle such as vegetation, rocks, or fences, to trap some of the sand. Sand dunes form when moving air slows down on the downwind side of an obstacle.down on the downwind side of an obstacle.

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Types of Sand Dunes:Types of Sand Dunes:

Barchan dunesBarchan dunes -- crescent-shaped dunes. They form in areas where there is a hard ground surface, acrescent-shaped dunes. They form in areas where there is a hard ground surface, a

moderate supply of sand, and a constant wind direction.moderate supply of sand, and a constant wind direction.

Transverse dunes-Transverse dunes- large fields of dunes that resemble sand ripples on a large scale. Consist of ridges oflarge fields of dunes that resemble sand ripples on a large scale. Consist of ridges of

sand with a steep face in the downwind side, form in areas where there is abundant supply of sand and asand with a steep face in the downwind side, form in areas where there is abundant supply of sand and a

constant wind direction.constant wind direction.

Linear dunes -Linear dunes - long straight dunes that form in areas with a limited sand supply and converging windlong straight dunes that form in areas with a limited sand supply and converging winddirections.directions.

Parabolic dunesParabolic dunes -- are "U" shaped dunes with an open end facing upwind. Form in areas with abundantare "U" shaped dunes with an open end facing upwind. Form in areas with abundant

vegetation and constant wind. Most common in coastal areas.vegetation and constant wind. Most common in coastal areas.

Star dunesStar dunes - dunes with variable arms and slip face directions. Form in areas with abundant sand supply and- dunes with variable arms and slip face directions. Form in areas with abundant sand supply and

variable wind direction.variable wind direction.

Glacial EnvironmentGlacial Environment

glacier - a permanent (on a human time scale) body of ice that shows evidence of downward movement due toglacier - a permanent (on a human time scale) body of ice that shows evidence of downward movement due togravitational pull.gravitational pull.

Formation of GlaciersFormation of Glaciers

Form at or aboveForm at or above snowlinesnowlineSnowlineSnowline - where ice can be created and remain all year round- where ice can be created and remain all year roundThe snowline, at present, lies at sea level in polar latitudes and rises up to 6000 m in tropical areas.The snowline, at present, lies at sea level in polar latitudes and rises up to 6000 m in tropical areas.

Form by recrystallization of snow due to pressure of overlying compacted snow.Form by recrystallization of snow due to pressure of overlying compacted snow.

Recrystallized snow has decreased air and increased grain size and density forming solid blocks of ice.Recrystallized snow has decreased air and increased grain size and density forming solid blocks of ice.

Barchan Longitudinal

ParabolicTransverse

Star

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Types of GlaciersTypes of Glaciers

Alpine/Mountain GlaciersAlpine/Mountain Glaciers

Relatively small glaciers at higher elevations in mountainous regions.Relatively small glaciers at higher elevations in mountainous regions.Ice Sheets: (Continental glaciers):Ice Sheets: (Continental glaciers):

the largest types of glaciers on Earth.the largest types of glaciers on Earth.

cover large areas of the land including mountain areas.cover large areas of the land including mountain areas.

Modern ice sheets cover Greenland and Antarctica.Modern ice sheets cover Greenland and Antarctica.Ice Shelves:Ice Shelves:

are sheets of ice floating on water and attached to land.are sheets of ice floating on water and attached to land.

usually occupy coastal embayments.usually occupy coastal embayments.

Glacial ErosionGlacial Erosion

PluckingPlucking-particle detachment by moving glacial ice-particle detachment by moving glacial iceAbrasionAbrasion

--debris in basal ice grinds into the bedrock and produce:debris in basal ice grinds into the bedrock and produce:

Glacial striationsGlacial striations - long parallel scratches and grooves that- long parallel scratches and grooves that are produced by rocks embedded in the iceare produced by rocks embedded in the ice

scraping againstscraping against the rock underlying the glacier.the rock underlying the glacier.Glacial polishGlacial polish - rock that has a smooth surface produced as- rock that has a smooth surface produced as a result of fine grained materiala result of fine grained material

embedded in the glacierembedded in the glacier acting like sandpaper on the underlying surface.acting like sandpaper on the underlying surface.

Landforms produced by mountain glaciersLandforms produced by mountain glaciers

CirquesCirques - bowl shaped depressions that occur at the heads of mountain glaciers- bowl shaped depressions that occur at the heads of mountain glaciers

Glacial ValleysGlacial Valleys - Valleys that once contained glacial ice become eroded into a "U" shape in cross section.- Valleys that once contained glacial ice become eroded into a "U" shape in cross section.

ArtesArtes- If two adjacent valleys are filled with glacial ice, the ridges between the valleys can be carved into a- If two adjacent valleys are filled with glacial ice, the ridges between the valleys can be carved into a

sharp knife-edge ridge, called an arte.sharp knife-edge ridge, called an arte.

HornsHorns - Where three or more cirques are carved out of a mountain, they can produce a sharp peak called a- Where three or more cirques are carved out of a mountain, they can produce a sharp peak called a

horn.horn.

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Hanging ValleysHanging Valleys - A valley that has greater elevation than the valley to which it is tributary.- A valley that has greater elevation than the valley to which it is tributary.FjordsFjords - narrow inlets along seacoasts once occupied by a fjord glacier.- narrow inlets along seacoasts once occupied by a fjord glacier.

Glacial DepositsGlacial DepositsSince glaciers are solid they can transport all sizes of sediment, from huge house-sized boulders to fine-grainedSince glaciers are solid they can transport all sizes of sediment, from huge house-sized boulders to fine-grainedmaterial.material.

Glacial DriftGlacial Drift general term for glacial deposits general term for glacial deposits

TillTill- nonsorted glacial drift deposited directly from melting ice. A till that has undergone diagenesis and has- nonsorted glacial drift deposited directly from melting ice. A till that has undergone diagenesis and has

turned into a rock is called a tillite.turned into a rock is called a tillite.MorainesMoraines linear deposits of till produced by the movement or retreat of glaciers linear deposits of till produced by the movement or retreat of glaciers

.. Glacial Marine driftGlacial Marine drift Unsorted chaotic deposits of sediments/rocks on seafloor or lakebeds brought by melted glaciers.Unsorted chaotic deposits of sediments/rocks on seafloor or lakebeds brought by melted glaciers. Large single rock bodies at the floor of a water body is called aLarge single rock bodies at the floor of a water body is called a dropstonedropstone..

The Ice AgesThe Ice AgesBegan between 10,000 to 2 myaBegan between 10,000 to 2 mya

Pleistocene epochPleistocene epoch North America covered in large ice sheetsNorth America covered in large ice sheets Glacial and Interglacial periods occurredGlacial and Interglacial periods occurred

Major fluctuations in sea levelMajor fluctuations in sea level

What caused the Ice Ages?What caused the Ice Ages?

Serbian mathematician Milutin MilankovitchSerbian mathematician Milutin Milankovitch

Milankovitch cycle - orbital cycles of the Earth affecting amount of solar radiationMilankovitch cycle - orbital cycles of the Earth affecting amount of solar radiation

Tilt of the Earths axis (every 41,000 years, 21.5 24.5 deg)Tilt of the Earths axis (every 41,000 years, 21.5 24.5 deg) Precession of Earths spin axis (every 23,000 years)Precession of Earths spin axis (every 23,000 years) Eccentricity of Earths orbit around the Sun (every 100,000 years)Eccentricity of Earths orbit around the Sun (every 100,000 years)

Effects of the 3 Orbital CyclesEffects of the 3 Orbital Cycles

Fluctuations on solar radiation received by EarthFluctuations on solar radiation received by Earth Combined orbital cycles affected paleoclimateCombined orbital cycles affected paleoclimate

Sea levels fluctuated in connection with orbital cycleSea levels fluctuated in connection with orbital cycle

TRANSITIONAL ENVIRONMENTSTRANSITIONAL ENVIRONMENTSTransitional environments are those environments at or near the transition between the land and the sea.Transitional environments are those environments at or near the transition between the land and the sea.

DeltaDelta prograding depositional bodies that form at the point where a river drains into a lake or sea.prograding depositional bodies that form at the point where a river drains into a lake or sea.Parts of a Delta:Parts of a Delta:

delta plain - composed of meandering flood plains, swamps, and beach complex.delta plain - composed of meandering flood plains, swamps, and beach complex.

delta front - steeper part.delta front - steeper part.

prodelta - broadly sloping that grades into the open shelf.prodelta - broadly sloping that grades into the open shelf.

Factors Affecting Delta Formation and Facies:Factors Affecting Delta Formation and Facies:water and sediment yield of the riverwater and sediment yield of the river

differences in river/sea water densities, buoyancy, salinitydifferences in river/sea water densities, buoyancy, salinity

shelf slope and topographyshelf slope and topographywave and tidal energy acting on the coastwave and tidal energy acting on the coastalong shore winds and currents,along shore winds and currents,

tectonics (subsidence) of the receiving basintectonics (subsidence) of the receiving basin

Types of DeltasTypes of DeltasRiver-dominatedRiver-dominated

large sediment volumelarge sediment volume

lobate shape = moderate sediment supplylobate shape = moderate sediment supply elongated when sediment supply is largeelongated when sediment supply is large

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Tide-dominatedTide-dominated

linear features parallel to tidal flow and perpendicular to shore.linear features parallel to tidal flow and perpendicular to shore.Wave-dominated deltaWave-dominated delta

smoothly arcuate; wave action reworks sediment.smoothly arcuate; wave action reworks sediment.

much sandier than the other types of delta.much sandier than the other types of delta.

Delta sedimentsDelta sedimentsSand, mud, sometimes gravelSand, mud, sometimes gravel

Decrease in grain size as you move away from landDecrease in grain size as you move away from land

General coarsening upward due to progradationGeneral coarsening upward due to progradation

LagoonLagoonshallow salt water body separated from the deeper sea by a shallow or exposed sandbank, coral reef, orshallow salt water body separated from the deeper sea by a shallow or exposed sandbank, coral reef, or

similar featuresimilar feature

quiet waters allow fine silt and clays to settle out of suspension, forming sequence of mudstone and shalequiet waters allow fine silt and clays to settle out of suspension, forming sequence of mudstone and shale overgrown with vegetation forming salt marshes, coal, and peat swamps, or algal mats.overgrown with vegetation forming salt marshes, coal, and peat swamps, or algal mats.

some cases, evaporites are formed.some cases, evaporites are formed.

BeachBeach-shore of a body of water formed and washed by waves and tides.-shore of a body of water formed and washed by waves and tides.

usually covered by sandy or pebbly materialusually covered by sandy or pebbly material

usually well sorted sand and pebbles, accompanied by mud, cobbles, boulders, smooth rocks and shellusually well sorted sand and pebbles, accompanied by mud, cobbles, boulders, smooth rocks and shell

fragments.fragments.Wave actionWave action

Longshore driftLongshore drift

the movement of sediment along a beach by swash and backwash of waves that approach the shore obliquely.the movement of sediment along a beach by swash and backwash of waves that approach the shore obliquely. Longshore currentLongshore current

a current that moves parallel to a shorea current that moves parallel to a shore

formed from the momentum of breaking waves that approach shore obliquely.formed from the momentum of breaking waves that approach shore obliquely.

SpitSpit long ridge of sand deposited by longshore current and driftlong ridge of sand deposited by longshore current and drift -- attached to a land at upstream end.attached to a land at upstream end.

TomboloTombolo

- a sand or gravel bar that connects an island with the mainland or another island.- a sand or gravel bar that connects an island with the mainland or another island.

MARINE ENVIRONMENTMARINE ENVIRONMENTShallow marineShallow marine

ReefsReefs

Continental shelfContinental shelf

Deep marineDeep marine

Submarine canyons and fansSubmarine canyons and fansPelagicPelagic

ReefsReefswavewave--resistant, moundresistant, mound--like structures usually made of fossiliferous carbonates (coral reefs) and/or sandlike structures usually made of fossiliferous carbonates (coral reefs) and/or sandbuild up on continental shelvesbuild up on continental shelvesFringing ReefsFringing Reefs

coral reef that is directly attached or borders the shore of an island or continent.coral reef that is directly attached or borders the shore of an island or continent.

Barrier ReefsBarrier Reefsa long narrow coral reef roughly parallel to the shorea long narrow coral reef roughly parallel to the shoreseparated from it at some distance by a lagoon.separated from it at some distance by a lagoon.

AtollAtoll

continuous or broken circle of coral reef and low coral islands surrounding a central lagoon.continuous or broken circle of coral reef and low coral islands surrounding a central lagoon.

Continental ShelfContinental Shelfcontinuous with the coastal plain sequences of the continentscontinuous with the coastal plain sequences of the continents

part of the continental margin that is between the shoreline and the continental slope (~200m).part of the continental margin that is between the shoreline and the continental slope (~200m).carbonates, sand and mud.carbonates, sand and mud.

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fossils are mostly marine invertebratesfossils are mostly marine invertebrates

Carbonate compensation depthCarbonate compensation depthCCDCCD

Depth where the rate of dissolution and precipitation of carbonates is equalDepth where the rate of dissolution and precipitation of carbonates is equal

Below this depthBelow this depth very little or no carbonatesvery little or no carbonates

Continental SlopeContinental Slopebetween the continental shelf and continental shelf and continental rise (oceanic trench)between the continental shelf and continental shelf and continental rise (oceanic trench)

Continental RiseContinental Rise between continental slope and abyssal plainbetween continental slope and abyssal plain

gentle incline and generally smoothgentle incline and generally smooth topographytopography

may bear submarine canyons and fansmay bear submarine canyons and fans TURBIDITESTURBIDITES

Abyssal PlainAbyssal PlainPelagicPelagic open oceanopen ocean

flat region of the ocean floorflat region of the ocean floor

covered with pelagic mud with fine sand layers from distal turbiditescovered with pelagic mud with fine sand layers from distal turbiditesfine-grained limestones (micrite), chertfine-grained limestones (micrite), chert

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LECTURE 8

GROUNDWATERa hidden reserve

--drinking waterdrinking waterfor more 50% of all people- 40% ofirrigationirrigation water- important forlivestocklivestock & industryindustry

-an overusedoverused resource resulting in:- water shortages- land subsidence- Contamination

-Underground lakes and rivers are rare-Mostunderground water exists in spaces between grains(in pore spaces)

-geological important erosional agent-geological important erosional agent

Origin of GroundwaterOrigin of GroundwaterGlaciers and ice capsGlaciers and ice caps 2.142.14

GroundwaterGroundwater 0.610.61

Surface waterSurface water 0.0090.009

Soil moistureSoil moisture 0.0050.005

AtmosphereAtmosphere 0.0010.001

Groundwater is the largest source of readily available freshwater.Groundwater is the largest source of readily available freshwater.

It has:It has: (1) less bacteria due o the natural(1) less bacteria due o the natural

filtering effect of rocksfiltering effect of rocks

(2) widespread(2) widespread

(3) constant temperature(3) constant temperatureGroundwateris all water contained in the spaces within bedrock and regolith.Hydrologic Cycle

Inflow =Outflow

Precipitation =Evapotranspiration + Runoff + GW

GW =Precipitation Evapotranspiration Runoff

Groundwater SystemGroundwater System--Layer of Soil MoistureLayer of Soil Moisture

--

Zone of AerationZone of Aeration open spaces in regolith or bedrock which are open spaces in regolith or bedrock which are

mainly filled with air (also called the vadose zone)mainly filled with air (also called the vadose zone)

--

Capillary FringeCapillary Fringe narrow fringe that is kept wet by narrow fringe that is kept wet by

capillary attraction that temporarily holds water.capillary attraction that temporarily holds water.

--

Water TableWater Table - boundary between the zone of aeration and- boundary between the zone of aeration and

zone of saturationzone of saturation

--

Zone of SaturationZone of Saturation all openings are filled with water. all openings are filled with water.

Groundwater storage & movementGroundwater storage & movement

Important factorsImportant factors

::

PorosityPorosity

Measures amount of water that can be held byMeasures amount of water that can be held by

rocks/sedimentsrocks/sediments

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Volume of voids / total volume of materialVolume of voids / total volume of material

Affected by grainsize, sorting and grain packingAffected by grainsize, sorting and grain packing

Poorly sortedPoorly sorted less porousless porous

Cubic vs rhombohedral packingCubic vs rhombohedral packing

PermeabilityPermeability

Ability to transmit fluidsAbility to transmit fluids

degree of interconnection of voids in the materialdegree of interconnection of voids in the material

Groundwater TransportGroundwater Transport

AquiferAquifer

Stores and transmits sufficient amount of waterStores and transmits sufficient amount of water

Confining unitsConfining units

AquitardAquitard stores, but slowly transmits water stores, but slowly transmits water

AquicludeAquiclude stores, but does not transmit water stores, but does not transmit water

AquifugeAquifuge does not store nor transmit water does not store nor transmit water

Types of AquiferUnconfined aquiferUnconfined aquifer

Bounded at the bottom by a confining unitBounded at the bottom by a confining unit

Water rises up to the water tableWater rises up to the water tablePerched aquiferPerched aquifer

Unconfined aquifer defined by a discontinuousUnconfined aquifer defined by a discontinuous

confining unitconfining unit

Local water table (usually above the main/regionalLocal water table (usually above the main/regional

water table)water table)

Confined aquiferConfined aquifer

Bounded at top and bottom by confining unitsBounded at top and bottom by confining units

Water rises up to the piezometric water level (also called potentiometric line/surface)Water rises up to the piezometric water level (also called potentiometric line/surface)

Darcys Law describes the rate of groundwater flow down a slope between two pointsDarcys Law describes the rate of groundwater flow down a slope between two points

Q = - KA (Q = - KA (H/L)H/L)

Q= discharge (volume of waterQ= discharge (volume of water

flowing in a given time)flowing in a given time)

K= hydraulicK= hydraulic

conductivity (a measure ofconductivity (a measure of

permeability)permeability)

A= area (through which the waterA= area (through which the water

flows)flows)

H= hydraulic headH= hydraulic head

L= length of path (between twoL= length of path (between two

wells)wells)

(-) sign means direction of Q is from high to(-) sign means direction of Q is from high to

low hydraulic headlow hydraulic head

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WellsWells

Wells can supply water - if they intersect the water table.Wells can supply water - if they intersect the water table.

Pumping a well at a rate faster than water can flow in the aquifer creates a cone of depression.Pumping a well at a rate faster than water can flow in the aquifer creates a cone of depression.

Groundwater recharge and discharge takes time!Groundwater recharge and discharge takes time!

The rate of movement of groundwater depends on many factors including the flowpath.The rate of movement of groundwater depends on many factors including the flowpath.

Manifestations of groundwater on the surface:Manifestations of groundwater on the surface: Springs, hot springs, geysersSprings, hot springs, geysers

SpringSpring-- Outflow of ground waterfrom water table intersectingEarths surface ( also oases)

hot springs- Spring w/ water 6-9oC (10-15o F)warmer than mean annual air temperature

Geysers - Intermittent hot fountains/columns of waterArtesian wellsArtesian wells

Wells tapping a confined aquifer.Wells tapping a confined aquifer.

Analogy: water supply from elevated water tanksAnalogy: water supply from elevated water tanksWater in the well rises above the top of the aquifer under artesian pressure, but does not necessarily reach theWater in the well rises above the top of the aquifer under artesian pressure, but does not necessarily reach the

land surface; a flowing artesian well is a well in which the water level is above the land surface.land surface; a flowing artesian well is a well in which the water level is above the land surface.

Geologic Work of GroundwaterGeologic Work of Groundwater-- CavernsCaverns-- Limestone, usually formed just below

water table

-- Karst topographyKarst topography-- Bedrock shaped (dissolved) bygroundwater (e.g. Chocolate hills in Bohol, HundredIslands)

- sink holes - Either gradual or abrupt depressionin surface due to dissolved limestone bedrock.

Groundwater problems and Contamination- Saltwater contamination or intrusion (coastalareas)

- Groundwater contamination (due to humancauses)

- Land subsidence

The removal of water allows the aquifer sediments to compact.The removal of water allows the aquifer sediments to compact.

Once compacted, the overlying unsaturated zone sediments will also drop in elevationOnce compacted, the overlying unsaturated zone sediments will also drop in elevation

- CAMANAVA enhanced flooodingExcessive groundwater extraction Compaction of aquifers Land subsidence increasedsusceptibility to floods

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Lecture 9 and 10MASS WASTING

Mass wasting - the process by which geologic materials (e.g., soil and rocks) are moved downslopefrom one place to another due to gravity

Major causes of mass movement:

SLOPE- the steeper the slope, the greater the downslope pull- for dry unconsolidated materials, smooth and rounded particles tend to support only very low-angleslopes while rough, sticky, or irregular particles can be piled more steeply without becoming unstable

Fluids- reduces friction- for unconsolidated materials, a little water present may add cohesion, but large increase in water

leads to instability

*Vegetation tends to stabilize slopes

Styles of motion:FALL - free-falling movement of materialsSLIDE - materials slips as a coherent unit along a clearly defined planeFLOW - materials move in a chaotically, with mixing of particles within the flowing mass

Mass wasting processes:RockfallRockslideSlumpMudflows

EarthflowsDebris AvalancheCreepSolifluction

Some preventive measures:

- Reduce slope angles to create stability.

- Reduce additional weights on unstable slopes.

- Enhance vegetative cover to stabilize slopes.

- Reduce moisture contents of materials through improved drainage.

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METAMORPHIC ROCKS

Metamorphism is the change undergone by an existing rock (e.g. igneous, sedimentary ormetamorphic), in the solid state, to another rock

Agents of metamorphism1. Heat

Sources of heat?1. Geothermal gradient - temperature increases with depth (20o 30oC per km in the crust)2. Large bodies of molten rock or intrusive bodies

Provides the energy to drive chemical reactions recrystallization of minerals2. PressureWhen subjected to confining pressure, minerals may recrystallize into more compacted forms.Confining pressure equal stress in all directions; from overlying rockDifferential stress unequal pressure in differ