`catena`. - GeoResource

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Soil Catena
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T O D AY I W I L L :
- U N D E R S TA N D W H AT A S O I L C AT E N A I S
BE ABLE TO EXPLAIN THE SEQUENCE OF SOILS
ALONG A SLOPE
Geography
Biosphere
In Scotland, in general, podzols are found in the
north east and brown earths in the east and
south east. However, there can be huge
variations in soil types across a small area.
This can be seen through a section diagram
across an altitude range - called a ‘catena’.
In a catena, the sequence of soil profiles which
develop down the slope relate to the relief and
altitude of the land.
Changing slope alters drainage, and the
leaching and gleying processes, whilst altitude
strongly influences the climatic effects in soil
formation.
Geography
Biosphere
Geography
Biosphere
Bedrock
Soil
Parent Material
Geography
Biosphere
Gley Soils
(NOT TUNDRA)
See page 11 of the summary notes on
information for the gley soil.
A gley forms at the bottom of the
slope because the area is waterlogged.
This is because there is flat land and
the water collects here from higher
altitudes. This happens as long as the
rock is impermeable. There is little
humification as there is very few soil
biota in the waterlogged conditions.
The soil is quite shallow as
weathering is slow.
Soil
Parent Material
Bedrock
Geography
Biosphere
Brown Earth
A brown earth forms on lower slopes
as it is the zonal soil for this climate
and vegetation. Some humification
takes place as the climate is still quite
mild and wet and the mild climate aids
decomposition. Leaching takes place as
precipitation exceeds evaporation – the
higher you go the more rain received.
Horizons are mixed because soil biota
mix the soil.
Bedrock
Soil
Parent Material
Geography
Biosphere
Podzol Soil
At the highest altitude we find podzol soil as it is
coldest here and particularly wet. The weathering
of the soil is slow due to the cold climate and
humification is slow as few biota live in the cold
conditions. There are distinct layers because of a
lack of mixing by the biota. Leaching and
podsolization occurs because precipitation exceeds
evaporation. An iron pan caused by re-deposited
iron impedes drainage. Sometimes the soil is
waterlogged as a result of this, and the flatter/gently
sloping relief.
Soil
Parent Material
Geography
Biosphere
[a] Annotate the three soil profiles to show the main characteristics of the soil.
[b] For each of the soils explain the processes which have created this soil profile.
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