Formation

Question 1

Factors affecting soil development ?

Answer 1

Parent Material
Climate
Living Organisms
Topography
Time

Question 2

Mechanical weathering types ?

Answer 2

1. Temperature Change
2. Wedge action of ice
3. Spreading of roots
4. Abrasion

Question 3

Mechanical - Temperature Change

Answer 3

1. Minerals have different coefficient of thermal expansion.
2. Unequal expansion and contraction due to temperature change.
3. Induced stresses cause particle detachment.

Question 4

Mechanical - Wedge action of Ice

Answer 4

1. Pores of rocks frozen.
2. Volume of ice > volume of water.
3. Large stresses form cracks due to wedging.

Question 5

Mechanical - Spreading of roots

Answer 5

1. Roots grow into cracks and fissures.
2. Forces act on rock.
3. Segments forced apart.

Question 6

Mechanical - Abrasion

Answer 6

1. Water, wind , glaciers move over rock surface.

2. Abrasion and scouring occur.

Question 7

Chemical weathering types ?

Answer 7

1. Hydration
2. Carbonation
3. Oxidation
4. Solution
5. Hydrolysis

Question 8

Chemical - Hydration

Answer 8

Water combines with minerals to form a new chemical compound.

Question 9

Chemical - Carbonation

Answer 9

1. Carbon dioxide in air reacts with rain.
2. Carbonic acid formed.
3. Carbonic acid reacts chemically with rocks.

Question 10

Chemical - Oxidation

Answer 10

Oxygen ions react combine with minerals

Question 11

Chemical - Solution

Answer 11

Rocks dissolve in water

Question 12

Chemical - hydrolysis

Answer 12

1. Water to H and OH
2. H replace metallic ions
3. New chemical composition

Question 13

Biological Weathering

Answer 13

Bacteria and other microorganisms

Question 14

Residual and transported soil

Answer 14

Residual: Soil remains at place of formation.
Transported: Deposited away from origin.

Question 15

Water (Alluvial) deposits

Answer 15

Lacustrine: deposits in lakes.
Marine: flowing water carries soils to ocean/sea.

Question 16

Air (Aeolian) deposits

Answer 16

Sand Dune: short distance, desert areas along coast/near lakes.
Loess (silt): Semi-arid - possess good dry strength.

Question 17

Glacial (drift) deposits

Answer 17

Till/boulder clay: melting of ice. (clay to boulders)

Glaciofluvial: moved by glacier, deposited later. (silt, silty clay and silt)

Question 18

Gravity deposits

Answer 18

Fallen rocks

Question 19

Combined action

Answer 19

Combination of transport methods.

Question 20

Soil consituents

Answer 20

Solid: Primary material (>0.002),Clay minerals(<0.002),Cementitious material (silica, iron oxide, calcite), organic matter (plant and animal remains).
Liquid: Water ( +ve/-ve pore water pressure) , dissolved salts (osmotic pressure)
Gaseous: Water vapour and air