Biosphere

Question 1

soil

Answer 1

thin surface layer of the earths crust and the foundation for plant life

Question 1

underlying bedrock

parent matrial

Answer 1

unweathered rock type found at the bottom of the soil

Question 2

regolith

weathered rock

Answer 2

top layer of bedrock which has begun to be broken down by the elements of the weather

Question 3

mineral matter

Answer 3

minerals derived from breaking down of bedrock by weathering

Question 4

oraganic matter

soil

Answer 4

material from decaying organic matter e.g. leaves, plants, roots, organisms

Question 5

eluviation

Answer 5

prcoess of rainwater washing organic matter down through the soil

Question 6

leaching

Answer 6

process of rainwater washing minerals down through the soil

e.g. iron

Question 7

illuviation

Answer 7

process of depositing mineral matter lower down in the soil

Question 8

capillary action

Answer 8

upward movement of water within a soil

Question 9

soil profile

Answer 9

name for a vertical cross section through a soil from the usrface to the underlying bedrock

Question 10

factors affecting soil formation

Answer 10

• underlying rock type
• vegetation type
• finish this card

Question 11

soil properties

(other than their profile)

Answer 11

• acidity (pH)
• grain size

Question 12

typical soil profile

Answer 12

• Ao - organic layer
• A - topsoil
• B - subsoil
• C - regolith (weathered rock)
• D - parent material (unweathered rock)

Question 13

podsol

soil profile

Answer 13

• commonly found in taiga (coniferous forest)
• Ao - partial slow decay of vegetation due to cold climate; trees have shallow roots so dont bring materials up from weathered bedrock; pine needles decompose to form an acidic infertile MOR humus
• A - high precipitation and snow melt mean leaching takes place and minerals are washed from the topsoil leaving it infertile and grey in colour
• redisposition of minerals (illuviation) leaves hardpan layer which can sometimes impede drainage making topsoil wet
• B - reddish-brown layer due to leached minerals being redeposited (illuviation)
• C - parent material
• few organisms in soil means very little mixing and therefore distinct layers

Question 14

brown earth

soil profile

Answer 14

• commonly found in temperate climate zones
• Ao - deap leaf litter which decays in warm climate to provide a rich fertile MULL humus (moderate rainfall helps this process)
• A - long tree roots bring up materials from weathered regolith producing fertile topsoil; precipitation > evaporation so some leaching occurs, but minerals remain in topsoil leaving it dark in colour
• B - the subsoil is also brown in colour due to some leaching of minerals (e.g. iron and aluminium) from the topsoil
• C - underlying rock type often sedimentary, this weathers easily releasing minerals into the soil
• no distinct horizons due to presence of biota, well aerated soil

Question 15

gley

soil profile

Answer 15

• commonly found in tundra climate zones
• Ao - partially decayed peat like MOR humus - cold climate so slow decay of shrubs and heaths
• A - heavy rainfall/snow melt leaches minerals out of the soil, leading to a greyish infertile topsoil
• B - gleying occurs - pore spaces filled with water so lack of oxygen, this means oxygen is taken from iron compounds turning them from a red ferric colour to a grey ferrous colour; some red flecks (mottling) where iron compounds havent been fully broken down - due to small air pockets where reoxygenation takes place when soil dries out in summer
• C - frozen subsoil/permafrost/high water table (if flood plain) means water cannot drain away leading to waterlogging
• few organisms due to cool anaerobic conditions so little mixing occurs therefore distinct horizons