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Kuala Lumpur, Malaysia

FORMATIVE ASSESSMENT: II

CLASS : 9 Ref.: 2016-17/ FA 2 /STD 9 /SST/HO-03

NAME : SUBJECT: Geography

DATE: 27th June, 2016 TOPIC : UNIT-2 LANDFORMS

LANDFORMS

Lithospheric plates are broken into a number of plates. These plates move around very slowly – just

a few millimeters each year due to movement of the molten magma inside the Earth. The molten

magma inside the Earth moves in a circular manner. The movement of these plates causes

changes on the surface of the Earth forming various landforms.

Earth movement can be on the basis of FORCE

• Endogenic forces-The forces which act in the interior of the Earth. Some scientists think that

these forces are caused by contraction of Earth on cooling, change in the rotation of the

Earth due to the action of the radioactive elements. These forces are produced and act on

the surface of the Earth. Wind, water and snow are such forces which erode the surface of

the Earth or make depositions on it. These external (exogenetic) forces are also called

processes.

• Exogenic forces -The forces that work on the surface of the Earth are called as

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FORCE can be subgroup on the basis of INTENSITY

1. Sudden Endogenetic forces-Volcanic eruption Earthquake where Landscape undergoes

disintegration suddenly.

2. Diastrophic forces-These forces act very slowly For eg Baltic sea rises by 1.3 metres in a

century

The systematic study of topographic relief forms is known as Geomorphology

geo- earth

morph-form

ology-science

Broadly - 3 main landforms-

• A Plain is a flat surface or gently rolling with elevation not more than 200 m from the sea

level. In some case it may be higher than 200 m, they are referred as high plains e.g.

Mississippi plain (USA) and Ganga plain (India)

Important plains of a) Asia : Yang-tze plain, Hwang-ho river (Yellow river) plain, Indus plain b) Africa: Nile Plain c) North America: Mississippi Plain d) South America: Amazon Plain e) Europe: North European Plain f) Australia: Murray-Darling Plain

• A Plateau is an elevated flat or rolling land standing above from the surrounding area with at

least one side by steep slope. E.g. Arabian plateau and Tibetan plateau etc

Important Plateaus of a) Asia : Tibet b) Africa : East African Plateau c) North America : Colorado Plateau d) South America : Andean Plateau e) Europe : Central Russian upland f) Australia : The great Austrian desert

• A Mountain is a land surface higher than the surrounding area with broad base and narrow

summit. The height of the mountain is a subject matter of human judgement. The Pilni /Pilani

hill of South India is only 1500 m when compared with mighty Himalayas.

(a) Highest Mountain in the World (and Asia) Mt. Everest, Nepal-China: 29,035 feet / 8850 meters (b) Highest Mountain in Africa-Mt. Kilimanjaro, Tanzania: 19,340 feet / 5895 meters (c) Highest Mountain in North America-Mt. McKinley (Denali), Alaska: 20,320 feet / 6194 meters (d) Highest Mountain in South America Mt. Aconcagua, Argentina: 22,834 feet / 6960 meters (e) Highest Mountain in Europe-Mt. Elbrus, Russia (Caucasus): 18,510 feet / 5642 meters (f) Highest Mountain in Australia-Mt. Kosciusko: 7310 feet / 2228 meters (g) Highest Mountain in Antarctica-Mt. Vinson Massif: 16,066 feet / 4897 meters

Evolution of landforms

Prof. William Morris Davis (1850-1934 AD) (Harvard University) around 1890 AD proposed

the systematic study of landforms.He propounded that as the surface uplift agents of

Denudation (Denudation is the process of levelling of the Earth surface by cutting form

higher regions and depositing the sediments in depressions) start working on it to bring

it down up to the base level. The base level is the point up to which erosion is possible. In

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general the base level is the sea level because all erosions activities can be done till the sea

level. Below sea level only depositional activities can take place

Denudation creates different types of landforms involving Weathering, mass wasting, and

Erosion etc.Denudation is the long-term sum of processes that cause the wearing away of

the Earth’s surface by moving water, ice, wind and waves, leading to a reduction in elevation

and relief of landforms and landscapes. Endogenous processes such as volcanoes,

earthquakes, and plate tectonics uplift and expose continental crust to the exogenous

processes of weathering, erosion, and mass wasting.

• Weathering is the process of decomposing and disintegrating of Earth surface (rocks) due to

exposure at or near the Earth surface. It changes hard rock into fine fragments and soft

residual masses.

• Mass wasting is Earth and rock movement due to sliding, rolling, flowing or creeping down

from slopes under the influence of gravity.

• Erosion is the wearing away of the top layer of the Earth’s surface by different agents of

Denudation e.g. running water, blowing wind, moving glacier, etc.

• Deposition is the process of settling down of sediments

• There are four factors which influence the type and rate of Rock Weathering.

• Rock structure- physical and chemical characteristics of rocks

• Climate- temperature and humidity

• Topography- amount of rock exposure, kind of precipitation, temperature

• Vegetation- amount of decaying organic matter

Conditioning factors of weathering There are four factors influence the type and rate of rock weathering.

1. Rock structure - The Minerals forming the rock in part determine whether it is more susceptible to chemical or physical weathering. Physical features such as joints, lesser fractures, bedding lanes and faults to a large degree determine the ease with which moisture enters the rock.

2. Climatic Factors of temperature and humidity determine not only the rate at which weathering proceeds but also whether chemical or physical processes predominate.

3. Topography affects the amount of rock exposure and also has important effects upon such factors as the amount and kind of precipitation, temperature and indirectly the kind and amount of vegetation.

4. Vegetation influences the rate and type of weathering by determining the extent of rock outcrops and the amount of decaying organic matter from which carbon dioxide and hemic acids may be derived.

Weathering process can be divided into two large groups Physical Weathering or Mechanical weathering Chemical weathering. 1) Physical weathering /Mechanical weathering - disintegration of rocks into fine particles from massive rock. sub- tropical mid-latitude regions(where temperature is quite high) Types of weathering

a) Granular disintegration – disintegrated into small particles due to expansion and

contraction during day and night.

b) Exfoliation: disintegrated in the form of layer from top to bottom.

c) Block disintegration: disintegrated in the form of blocks.

d) Shattering: disintegration in which rocks are broken into small pieces with angle and sharp

corners edges.

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e) Organic: Plants and trees pressure on the surface of the rock

2) Chemical weathering- decomposition of soil and rock (change in composition) by chemical processes. When water fall on the surface they react with chemical present in the soil and produce

different types of landforms. Among all agents of Denudation river is the most active

• Gullies or irregularities in the surface of the ground. The gullies join up and form small

streams.

• Erosion begins with the birth of every stream. Rivers erode sediments from higher regions

and deposit it in lower areas

There are mainly three activities involved in landform creation namely

• Erosion-progressive removal of mineral material from the sides and floor of the river channel.

• Transportation-movement of the eroded particles by dragging along the bed by suspension in

the water.

• Deposition-accumulation of transported particle on the floor of stagnant waterbody into which

the rivers drain their water.

• A stream always follows the shortest and easiest path downhill deepen the channel and

remove rock fragments. The power of the flushing water is sufficient to pull apart the loose

materials room the bed of the streams. This kind of mechanical erosion is known as

Corrasion.EG Pot holing is a special case of corrasive action. waterfall.

Hydraulic Action-The pressure of running water

Stream transportation

3 principleform i.e.

• Dissolved matter is transported invisibly in the form of chemical ions.

• Suspended load are those particles that remain hanging and flow in turbulent eddies in the

stream.

• Bed load are those heavy particles that settle down on the river bed and they roll or slide on

the river bed.

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The work of rivers

If a typical stream from its source to its mouth is flowed then three visible sections can be seen:

(1) The Upper Mountain Course, where the main work is that of erosion.

(2) The Middle Plain Course, where the main work consists of the transportation of the

material eroded. There is also some amount of deposition.

(3) The Lower Delta Course, where deposition of the transported material is the main work

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The three stages in the life of a river

• Youth stage: Streams that have just entered upon their work of erosion and still have rather

steep gradients are called young streams. A Young stream is a powerful agent of erosion

with abrupt changes in gradient. Steep walled canyons, rapids and waterfalls. Young rivers

with their rapids and waterfalls are not suitable for navigation, but they are useful for

hydroelectricity

• A mature valley is wider. It has a broad flood plain and a slight gradient. It swings from side

to side and the work of widening becomes more rapid than that of deepening. The valley floor

becomes flat and does not have the narrow V shaped cross section characteristic of a young

stream. A mature river may have several well developed tributaries.

• Old age: In this stage, the water flows sluggishly and there are numerous meandering

streams. There are no waterfalls, no rapids. The valley becomes broad and shallow, and the

work of erosion comes almost to a standstill.

.

Glaciers are slow moving river of crystalline ice masses found in high latitude and altitude areas

In cold regions snowfall ice gets accumulated and compacted due to weight of layers of snow. The

snow at the bottom get compressed and crystallized into dense ice called Firn or Nave.

Continental Glaciers-thick layer of ice on a flat surface Greenland and Antarctica

Valley/Mountain/Alpine glaciers-are tongue shaped. When these glaciers descend on the mountain

slope and reach below the snowline they start melting .The floating ice blocks are called Ice Bergs

When small peaks peep out of the continental glaciers surface they are called as Nunatkas

A very massive size of floating ice bergs are called as Ice Shelves.

Of the entire world’s water only about six tenths of one percent is found underground. This water is

stored in aquifer below the Earth surface. Water saturated zone of rocks are called Groundwater.

The upper limit of groundwater is called the Water table. Groundwater is an important erosional

agent. The powerful dissolvent agent makes several interesting features. The action of groundwater

is most active in limestone or calcareous cement areas. Rain water when get mixed with

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atmospheric Sulphur dioxide and carbon dioxide and fall on the limestone area, which actively

erodes the surface.

Beaches

They are formed by deposition of sand, gravels, pebbles and marine organism shells laid down

along the coast.

Beaches made up of gravels and pebbles are called Shingle Beaches

Beaches made up of sand are called Sandy Beaches.

Spits: Spits are long slender sandbars deposited by sea waves. They are connected with

the mainland from one side while another side ends into open water of sea. When

another spit develops from the main one towards the mainland, they are called Hook or Hooked

Spit.

Tombolo: Tombolo is sandbar connecting an island with the main land.

Lagoon: Lagoon is an enclosed water body. When sandbar develops along the coast and

encloses the sea water leaving a small inlet through which water can move in or out is called

lagoon.

Eolian Landforms

Eolian landforms are made by the action of wind in arid [dry] regions of the world.

Strong winds are quite common in arid and semi-arid regions of the world. Strong wind

Sea Beaches Features of Coastal erosion picks up sand particles from one place to another and

while transporting and deposition they make several interesting landforms.

There are three main types of action which are responsible for landforms creation. Abrasion or

Corrasion: Strong winds lift sand particles and blast sand particles on stones or rocks lying in their

path. Blasting of sand particles cause scooping out of rock.

Deflation: the process of lifting and removal of loose material from the Earth’s surface.

Attrition: the mutual wearing of sand particles is called attrition.

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Soil and its formation

The brown loose grainy particle that covers most of the Earth’s land surface is called soil.

The layer of soil itself is dynamic in which many complex chemical, physical and biological

activities go on simultaneously. Soil is made up of substance existing in three states Solid,

Liquid and Gaseous. The solid portion of soil consists of both Inorganic and Organic material.

Soil texture: Soil texture means the particle size that makes the soil. Particles are classified as

various grades of

• Gravel particles 1mm to 2 mm in diameter,

• Sand particles 1 mm to 0.05 mm in diameter,

• Silt particles 0.05mm to 0.005 mm in diameter and

• Clay particles less than 0.005mm in diameter.

The Bureau of Soils of the US Department of Agriculture describes various soil textures

• Sand – 80% or more sand and 20% of less silt or clay.

• Sandy loam – more than 20% but less than 50% silt and clay while remaining sand.

• Loam – 20% clay, 30-50 % silt and 30-50 % of sand. (Silt loam if silt predominates or clay

loam if clay predominates).

• Clay- contains 80% or more clay and silt, 10-20 % of sand.

• Soil texture is important to determine the water retaining capacity of the soil. Too grainy soil

will drain the water while the clay soil particles are so small that they do not allow water to percolate

easily.

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Vertical section of the soil showing different layers is called soil horizon. These are named after English alphabets as A, B and C. The top layer of the soil is called A Horizon (top soil). This is the most important layer for agriculture point of view as all agricultural activities take place in this layer only. The thickness of this layer varies from one region to another. Approximately it is 25-30 cm. in thickness in general condition. In warm and humid areas there a very thin layer of dark brown colour substance above top soil called as the Humus Layer or O Layer. The Humus layer is very fertile. Immediately below the A Horizon is Horizon B. Horizon B layer soil have coarser grain and less nutrient minerals. This is termed as sub soil. The thickness of this layer ranges from the bottom of top soil to a few meters downwards. Micro nutrient washed away from the top layer gets deposited in sub soil thus it is also called as Zone of accumulation. Too much of fine clay particles accumulated in subsoil makes it extremely dense and impermeable. Such dense layer is called as Hardpan. Below the sub-soil is the C horizon. C horizon mostly consists of partially altered parent rock and very little or no organic matter. About 2-3 meters from the surface starts the zone of subsoil. Below this layer is the platform of bed rock. The humus layer, top soil and subsoil together called as Solum or true soil. All processes of soil formation and living roots, animal life are confined in this layer only. A thin layer of soil takes several hundreds of years to form get washed away by several activities. Factors affecting soil formation

There are many processes and influences that are involved in the formation of soil which are

together known as soil formers.

Passive condition Parent material or rock

Topography or relief

Time

Active agents Climate

Biological activities

Causes of soil erosion Land use: Humans play a major role in soil erosion through their use and abuse of natural resources, for example; deforestation, grazing, arable land use, faulty farming systems, high crop intensity, housing construction, mining etc.

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Climate: Climate: The two most important climatic factors having a direct effect on erosion are Precipitation and Wind Velocity. Other climatic factors have an indirect effect on soil erosion. For erosion control it is necessary to investigate physical characteristics of rainfall, including the amount, distribution, intensity, energy load, seasonality and variability of rainfall and the formation and course of surface run off. Soil: The susceptibility of a soil to erosion is influenced by its physical, hydrological, Chemical and Mineralogical properties as well as its Soil profile characteristics. Important Soil physical and hydrological properties that affect the resistance of a soil to erosion include texture, structure, transmission properties and water retention. Hydrology: Infiltration, surface detention, overland flow velocity, and subsurface water flow are important soil erosion components of the hydrological cycle. The different types of flow and their velocities may be turbulent or laminar, steady or unsteady, uniform or non-uniform and influence the extent of erosion Landforms: Slope gradient, slope length and shape of slope are the important variables of landform that affect erosion processes for all types of soil erosion, e.g.;, splash, sheet, rill, and gully erosion. Soil erosion causes two main problems: Loss of soil productivity: When topsoil erodes, the less fertile and harder B horizon becomes exposed. This leads to lower forage production, lower water infiltration and greater run off. Sediment pollution: When eroded sediment is rich in fertilizers or pesticides, it can upset the ecosystem at its point of deposition. In addition, sediments may damage machinery, agitate respiratory problems and reduce visibility. Ways to conserve soil Plant trees: We all know that the roots of trees firmly hold on to the soil. As trees grow tall, they also keep rooting deeper into the soil. As the roots of the trees spread deep into the layers of soil, they contribute to the prevention of soil erosion. Soil that is under a vegetative cover has hardly any chance of getting eroded as the vegetative cover acts as a wind barrier as well. Terraces: Terracing is one of the very good methods of soil conservation. A terrace is a levelled section of a hilly cultivated area. Owing to its unique structure, it prevents the rapid surface run off of water. Terracing gives the landmass a stepped appearance thus slowing the easy washing down of the soil. Dry stonewalling is a method used to create terraces in which stone structures are created without using mortar for binding. No-till farming: When soil is prepared for farming by ploughing it, the process is known as tilling. No-till farming is a way of growing crops without disturbing it through tillage. The process of tilling is beneficial in mixing fertilizers in the soil, shaping it into rows and preparing a surface for sowing. But the tilling activity can lead to compaction of soil, loss of organic matter in soil and the death of the organisms in soil. No-till farming is a way to prevent the soil from being affected by these adversities. Contour ploughing: This practice of farming across the slopes takes into account the slope gradient and the elevation of soil across the slope. It is the method of ploughing across the contour lines of a slope. This method helps in slowing the water run off and prevents the soil from being washed away along the slope. Contour ploughing also helps in the percolation of water into the soil. Crop rotation: Some pathogens tend to build up in soil if the same crops are cultivated consecutively. Continuous cultivation of the same crop also leads to an imbalance in the fertility demands of the soil. To prevent these adverse effects from taking place, crop rotation is practiced. It is a method of growing a series of dissimilar crops in an area sequentially. Crop rotation also helps in the improvement of soil structure and fertility. Soil pH: The contamination of soil by addition of acidic or basic pollutants and acid rains has an adverse effect on the pH of soil. Soil pH is one of the determinants of the availability of nutrients in soil. The uptake of nutrients in plants is also governed to a certain extent, by the soil pH. The maintenance of the most suitable value of pH, is thus, essential for the conservation of soil. Water the soil: We water plants, we water the crops, but do we water the soil? If the answer is negative, it is high time we adopt the method of watering soil as a measure of conserving soil. Watering the soil along with the plants is a way to prevent soil erosion caused by wind.

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Salinity management: The salinity of soil that is caused by the excessive accumulation of salts, has a negative effect on the metabolism of the crops in soil. Salinity of soil is detrimental to the vegetative life in the soil. The death of vegetation is bound to cause soil erosion. Hence, salinity management is one of the indirect ways to conserve soil. Soil organisms: Organisms like Earthworms and others benefiting the soil should be promoted. Earthworms, through aeration of soil, enhance the availability of macronutrients in soil. They also enhance the porosity of soil. The helpful organisms of soil promote its fertility and form an element in the conservation of soil. Indigenous Crops: Planting of native crops is known to be beneficial for soil conservation. If non-native plants are grown, the fields should be bordered by indigenous crops to prevent soil erosion and achieve soil conservation.

GLOSSARY

Aeolian: Aeolian refers to the erosion caused by winds or that is related to winds. Alluvial Fan: Alluvial Fan is a fan shaped soil deposit formed due to sediment usually found at the foot of the valley, where a stream fans out and deposits the sediments of the stream. Barchans: Barchans is an exact crescent shaped sand dune made by the winds. Base Level: The lowest level at which the erosion can take place is known as the base level. Bed Load: Bed load describes the flowing particles that are transported along the river bed with the currents. Canyon: A deep and wide steep valley is called a canyon. Cirque: A bowl shaped hollow carved on a mountain top is called a cirque. Cliff: A tall, steep and a vertical rock surface is called a cliff. Contour Line: Contour lines are the lines showing the places having the same height above sea level. Corrosion: Corrosion is erosion due to abrasion or rubbing. Crevasse: A deep crack in a glacier is known as crevasse. Debris: Debris is defined as the rubble that is left behind after destruction and damage.

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Decomposition: The process of conversion of organic matter into simpler substances by decomposers is called decomposition. Degradation: It is defined as the gradual wearing down of banks, rocks etc, which is caused by water and frost. Delta: In geographical terminology, a delta is a triangular plain, usually at the mouth of the river, where alluvial soil is deposited. Dendritic: Dendritic is a description of a stream which resembles the pattern of a tree. Denudation: Denudation means removal of soil from the surface layer and deposits it elsewhere. Distributary: A branch of a river that flows away from the river and never rejoins it. Diurnal: It means occurring in a period of 24 hours or which has a daily cycle. Emergent Coast: The coast where the land level is rising as compared to the sea level. Esker: A narrow elongated ridge made from coarse gravel, which is deposited by a flowing water stream is called esker. Estuary: A wide part of the river near the sea, where the salt water mixes with the freshwater. Fauna: Fauna refers to the animal species inhabiting a particular region. Fissure: It is a long narrow opening or a crack. Flora: Plants of a particular country, region or time is called flora. Fold Mountains: Mountains that are formed due to folding are known as Fold Mountains. Geologic Time: The time which refers to the formation and development of the Earth is known as geologic time. Gorge: A steep and narrow valley, which has steep rocky sides, is called a gorge. Groundwater: It is the reserve or a store of water created by percolation of water into the soil or into layers of bedrock. High Tide: High tide is when the water reaches its highest level. Lagoon: A protected water body which lies between a reef and the coastline is known as lagoon as per geography terms. Lake: A water body lying within the continental mass is termed as lake. Landslide: A rapid and sudden downward movement of a hill or a mountain mass made up of rocks, sand and gravel is called a landslide. Leaching: Leaching is the act of removing soluble minerals from the soil by percolation of liquids. Load: The rock and gravel material transported by river or any agent of erosion. Meander: It is a very pronounced and prominently looping bend in a river. Mesa: A hill having a flat surface at the top, but which rises prominently around the surrounding landscape is called a Mesa. Moraine: The movement of a glacier results in transportation of unwanted material from a place to another. So the debris that is deposited by the glacier is called moraine. Mouth: The spot where a river joins another water body is called the mouth of the river. Nunatak: An isolated mountain or hill which projects through glacial ice and is surrounded by ice sheets is called nunatak. Outwash Plain: In geographical glossary, outwash plain is defined as a flat, sloping surface that comprises gravel and rock debris, deposited by a network of glacial streams. Ox-bow Lake: An Ox-bow lake is a crescent-shaped lake that is formed when one of its meanders is cut-off or isolated. Percolation: The passage of a liquid substance, like water, through a porous object, like rocks or soil, is known as percolation. Rift Valley: A long valley formed along a rift in the Earth crust due to the gradual sinking of land between two parallel series of faults is called a rift valley. Sandbar: A sandbar, also known as a shoal or a sand bank, is a ridge of sand, partly exposed or submerged, formed along a shore or river. This ridge is built by the action of tides, currents or waves and consists of tiny pebbles, sand and silt. Sand Dune: A sand dune is a hill or mound of sand that is formed by the action of winds along shores or in desert areas. Sea-wave: In geographical terms, waves that indicate a horizontal energy movement but a vertical movement of water are known as sea-waves. Silt: Sedimentary material comprising tiny particles of rock larger than clay and smaller than sand.

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Strata: Strata can be defined as beds of rocks of a particular kind (usually sedimentary),comprising many uniform layers, that is formed naturally by materials that get deposited. U-shaped Valley: A U-shaped valley is a type of glacial valley, formed due to glacial erosion and characterized by steep walls and broad floors. V-shaped Valley: A V-shaped valley is a valley that has a cross-sectional profile and that is formed by the eroding action of streams. Waterlogged: Waterlogged is a phenomenon where an object is so filled or flooded with water that it seems to be heavy or unmanageable. Water Table: Water table means a planar underground surface beneath which, Earth materials such as soil or rock are saturated with water. At this level, the ground water pressure is equal to the atmospheric pressure. Wave-Cut Platform: A wave cut platform is the same as a wave cut notch. Wind: Wind refers to air moving from an area of high pressure to an area of low pressure. Windward: In simple words, the term windward refers to toward the wind. More so it directs toward the point from which the wind blows. Aerated soil: An aerated soil is a soil with a good movement of air through the soil structure. The opposite is a wet waterlogged soil. Alluvium: Alluvium is a deposit made by a river or running water. This leads to an‘alluvial deposit’ forming in the water. Clay: That mineral fraction of the soil with particles smaller than 0.002 mm in diameter. Evaporation: This is the rate of water loss from liquid to vapour (gaseous) state from an open water, wet soil or plant surface, usually expressed in mm day-1. Evapo-transpiration: The process by which water passes from a liquid to a vapour (gaseous) state through transpiration from vegetation, and evaporation from soil and plant surfaces. The rate of evapo-transpiration is usually expressed in mm day-1. Horizon: One of the layers that form in the soil profile as a result of soil-forming processes. Humus: Organic matter, also called ‘humus’, forms from the decay of leaves, plants and other life. Leaching: Leaching is the process where soluble materials (including nutrients and salts) in the soil are washed down the soil profile by water. Loam: Loam is a soil which contains clay, silt and sand as well as organic material. Organic Material: Organic matter, also called ‘humus’, forms from the decay of leaves,plants and other life. Parent Material: Soil parent material refers to the rocks which were weathered to form the soil in the first place. pH: pH is a measure of acidity; standing for Potenz Hydrogen. It is measured from 1 (acid) through 7 (neutral) to 14 (alkaline) expressed on a logarithmic scale. Most soil is about pH 3 to 8. Precipitation: Precipitation means water reaching the ground from rainfall, snow and hail. Sediment: Sediment is a deposit of ‘alluvium’ laid down in water (such as lakes or the sea). Sediments can, over time, form rocks such as chalk and limestone. Silt: That mineral fraction of the soil with particles from 0.002 - 0.063 mm in diameter Fine silt: 0.002 - 0.006 mm in diameter Medium silt: 0.006 - 0.02 mm in diameter Coarse silt: 0.02 - 0.063 mm in diameter Soil: Soil is a combination of four constituents: mineral material (sand, silt, clay and rock particles), organic material, air and water. Soil is made from the breaking down of rocks and organic matter by physical, chemical and biological processes. Soil Minerals: These refer to the trace elements found in soil also called nutrients. Texture: The description of the balance in the soil between the constituents including sand, silt and clay as well as organic matter. With experience, texture can be established by touch. Water Holding Capacity: Can the soil hold lots of water like a sponge? If so it has a large ‘water holding capacity’. Soil organic matter increases the water holding capacity. Pure running sand has a low water holding capacity.