Earth Science

Earth Science

• Earth Science– Earth science is the study of planet Earth, including its

structure, components, and essential characteristics.

– Earth science fields of study are further classified ac cording to specific topics, such as:

• geography: study of Earth’s landforms, features, climates, and environment.

• geology: study of Earth’s crust, including its compo sition and development.

• meteorology: study of Earth’s atmosphere, includ ing its composition and weather patterns.

• oceanography: study of Earth’s water, including fresh and salt water.

Earth Science

• The multidisciplinary Earth sciences are generally classified according to one of four general spheres, or domains, of Earth:– lithosphere: the outermost layer of rocky land.– hydrosphere: the combined water (solid, liquid, and

gas) found on and under the surface.– atmosphere: the enveloping layer of protective gas

around the surface.– biosphere: the region that supports and nurtures life

(includes portions of lithosphere, hydrosphere, and atmosphere).

Earth Science

• Geologic Calendar– Represents scientific understanding of age

and history of Earth.– Primarily divided into two eons: Precambrian

and Phanerozoic.

Earth Science

• PRECAMBRIAN:– Lasted from formation of Earth (about 4.6

billion years ago) to 570 million years ago.– Abundant life forms: algae, bacteria, fungi,

worms, and sponges.

Earth Science

• PHANEROZOIC:

• Lasted from 570 million years ago until the present.

• Divided into three eras: – Paleozoic– Mesozoic– Cenozoic.

The Three Eras of the PHANEROZOIC:

• Paleozoic:– 570—245 million years ago– Lack of fossil preservation– Diversity of life relatively unknown

The Three Eras of the PHANEROZOIC:

• Mesozoic:– 245 - 66 million years ago– First mammals and flowering plants appear– Dinosaurs flourish

The Three Eras of the PHANEROZOIC:

• Cenozoic:– 66 million years ago until the present– Mammals diversified and ruled the surface of

Earth– Primates first appeared

The Lithosphere

• Elements– Collection of atoms of the same type.– Simplest form of matter that:– Cannot be formed from simpler substances.– Cannot decompose into simpler substances.– Organized on the Periodic Table of the Elements:– Periodic Table contains 115 elements:– 92 elements found naturally.– 23 elements created artificially in laboratories.

The Lithosphere

• Minerals– Naturally occurring, inorganic, solid substances.– Formed when groups of atoms bond together.– Characterized by composition and arrangement of

atoms.– Classified by physical properties (composition):– Crystal habit, hardness, color, cleavage, luster– Classified by composition and crystal structure (ar

rangement of atoms):– Native elements, silicates, carbonates, halides,

oxides, sulfides, sulfates

The Lithosphere

• Rocks– Collections of minerals.– Classified into three natural types

• igneous, • meta morphic• sedimentary

– Distinguished by rock structure and mineral composition.

The Lithosphere

• IGNEOUS ROCK:– Forms as minerals from magma (hot, liquid

rock) crystallize.– Originates deep inside Earth.– Is pushed to surface by magma.– Has a texture that is determined by its rate of

cooling.

The Lithosphere

• METAMORPHIC ROCK:– Forms as a result of extreme pressure and/or

temperature.– Can alter and change pre-existing, older

rocks.– Can begin as either igneous or sedimentary

rock.

The Lithosphere

• SEDIMENTARY ROCK:– Originates as detritus (loose sediment) formed

from wind and water erosion.– Forms as detritus accumulates and compacts

to a solid mass.

Layers of the Earth

• Layers of the Earth– Earth is generally divided into three regions:

crust, mantle, core.– These layers are separated by density.

Layers of the Earth

• CRUST:– Acts as Earth’s hard Outer shell.– Divided into two parts by density: continental and

oceanic.– Continental:

• Located beneath surface— not covered with water• Approximately 30—40 km thick o much older than oceanic

crust• Consists mostly of igneous rocks o composed mostly of

granite and basalt– Oceanic:

• Located beneath the oceans o approximately 6—11km thick• Composed mostly of basalt

Layers of the Earth

• MANTLE:– located under crust—is almost 3,000 km thick.– contains nearly 80 percent of Earth’s total volume.– is divided into inner and outer mantle.– has temperatures ranging from 2,500°F—5,400°F– heat from core travels through the mantle to the crust

in circles called convection currents.– Convection currents are responsible for plate

tectonics.

Layers of the Earth

• CORE:– located approximately 3,000 km beneath sur face.– divided into inner and outer core.– outer core composed of molten nickel-iron.– inner core is solid because of intense pressure.– temperatures reach 6,700°F.– Outer core spins around inner core with rotation of

Earth.– Earth’s magnetic field is generated by rotation of ions

in molten core.

Plate Tectonics

• Plate Tectonics– Lithosphere broken into large, rigid plates.– major plates: African, North American, South American,

Eurasian, Australian, Antarctic, Pacific– minor plates: Arabian, Nazca, Philippines– Seismic energy from two plates interacting with each other

causes earthquakes. Intensity of earthquakes measured on the – Richter scale:

• categorizes earthquakes on a numeric scale.• each increase in number represents a 30x increase in energy

release.

– Plates interact by colliding into, moving away from, and rubbing against each other. These interactions create earthquakes, volcanoes, mountain ranges.

Plate Tectonics

• CONVERGENT PLATE BOUNDARIES:– Occur when plates collide or move into each

other.– Results include earthquakes, Andes and

Himalayan mountains.

Plate Tectonics

• DIVERGENT PLATE BOUNDARIES:– Occur when plates move away from each

other.– Results include oceanic ridges, East African

rift valley, Rio Grande rift.

Plate Tectonics

• TRANSFORM PLATE BOUNDARIES:– Occur when two plates rub against, or move

parallel to, each other.– Results include earthquakes along the San

Andreas Fault.

Plate Tectonics

• Distribution of Earth’s land developed through movement of lithospheric plates.

250 million years ago

All land is connected t-one super continent (Pangaea)

200 million years ago

Pangaea divides into northern Laurasia and southern Gondwanaland

100 million years ago

Laurasia and Gondwanaland break apart

50 million years ago

continents closely resemble current distribution

Geologic Processes

• SURFACE-MODIFYING PROCESSES:– leave behind evidence of activity on Earth’s surface.– are dynamic processes that continually change Earth.– can be slow and steady (e.g., erosion, sediment transport).– can be sudden and disastrous (e.g., earthquake, volcanoes).– human activity can speed up, cause, or otherwise affect natural

geologic processes:• farming and mining can speed up wind and water erosion.• deforestation can increase the occurrence of landslides and

mudflows.• global warming and climate change can both lead:

– directly to rising temperatures, melting glaciers, and rising sea levels.– indirectly to floods, earthquakes, hurricanes, and increased volcanism.

SURFACE-MODIFYING PROCESSES:

• Tectonism– fracture and deformation of Earth’s crust

• Volcanism– molten rock reaches surface– basaltic lava flows (fluid eruptions of molten rock)– pyroclastic flows (eruptions of solid debris such as

rock and ash)• Water- modifying / fluvial force

– water erosion– sediment transport– sandbar formation

SURFACE-MODIFYING PROCESSES:

• Aeolian process– wind erosion– rock carving and shaping– sand dune formation– sediment transport

• Glacial process– landscape leveling– sediment and rock transport– creation of fjords, crevasses, cliffs, rock formations

• Gravitational processes– landslides, mudflows, avalanches