L1 /
3
CH3041
SOIL PROFILES
• Soils are vertically stratified into horizons
- distinct horizontal layers result from the interactions among weathering processes.
- distinct horizontal layers result from the interactions among weathering processes.
• O Horizon
Surface layer of organic matter, dark brown.
Surface layer of organic matter, dark brown.
• A Horizon = Topsoil
finely divided minerals + organic matter, extensively leached, dark grey
finely divided minerals + organic matter, extensively leached, dark grey
cm
-
1.2m
-
1.2m
• B
Horizon = Subsoil
receives leached material from topsoil
receives leached material from topsoil
• C
Horizon = weathered parent rock
physically broken down bedrock
physically broken down bedrock
• Soil
classification: United
Classification System
Gravels 60-2 mm Sands 2-0.06 mm
Silts 0.06-0.006 mm Clays <0.006 mm
