PHSC 210 QUESTIONS AND ANSWERS LATEST EDITION GRADED A+
Weathering
physical and/or chemical breakdown of a rock in place
the process by which larger rocks get broken down into smaller pieces
the disintegration and decomposition of rock
Erosion
the removal of weathered material
Soils
a mixture of mineral and organic matter
Loam
a well-balanced soil (roughly equal sand/silt, organics, clay)
Rain
most important for soil-making
moderate rainfall (30-50 in/yr) helps foster deep soil formation
Soil Horizon
O horizon = humus
A horizon = topsoil
(E horizon = leaching zone)
B horizon = subsoil
C horizon = weathered bedrock
bedrock
Chemical weathering
occurs when a rock disintegrates due to chemical reactions that happen within the
environment
The formation of carbonic acid
Water + Carbon Dioxide <--> Carbonic Acid
H2O + CO2 <--> H2CO3
Carbonic Acid chemically erodes limestone (calcite CaCO3)
The solution of calcite by carbonic acid
Calcite + Carbonic Acid <--> Calcium + Hydrogen + Bicarbonate
CaCO3 + H2CO3 <--> Ca+2 + 2H+ + 2CO3-2
The rusting of rocks
Iron + Oxygen --> Rust (Hematite)
4Fe + 3O2 --> Fe3O4
Mechanical weathering
the physical breakdown of a rock into smaller pieces
Frost wedging
when water gets into the cracks of a rock and then proceeds to freeze (expanding)
Frost heaving
when freezing water lifts (and cracks) the road causing damage that must be repaired
the next summer
Root wedging
as the roots force open even small fractures, this leads the way to other weathering
processes, such as frost wedging in the winter
Weathering
physical and/or chemical breakdown of a rock in place
the process by which larger rocks get broken down into smaller pieces
the disintegration and decomposition of rock
Erosion
the removal of weathered material
Soils
a mixture of mineral and organic matter
Loam
a well-balanced soil (roughly equal sand/silt, organics, clay)
Rain
most important for soil-making
moderate rainfall (30-50 in/yr) helps foster deep soil formation
Soil Horizon
O horizon = humus
A horizon = topsoil
(E horizon = leaching zone)
B horizon = subsoil
C horizon = weathered bedrock
bedrock
Chemical weathering
occurs when a rock disintegrates due to chemical reactions that happen within the
environment
The formation of carbonic acid
Water + Carbon Dioxide <--> Carbonic Acid
H2O + CO2 <--> H2CO3
Carbonic Acid chemically erodes limestone (calcite CaCO3)
The solution of calcite by carbonic acid
Calcite + Carbonic Acid <--> Calcium + Hydrogen + Bicarbonate
CaCO3 + H2CO3 <--> Ca+2 + 2H+ + 2CO3-2
The rusting of rocks
Iron + Oxygen --> Rust (Hematite)
4Fe + 3O2 --> Fe3O4
Mechanical weathering
the physical breakdown of a rock into smaller pieces
Frost wedging
when water gets into the cracks of a rock and then proceeds to freeze (expanding)
Frost heaving
when freezing water lifts (and cracks) the road causing damage that must be repaired
the next summer
Root wedging
as the roots force open even small fractures, this leads the way to other weathering
processes, such as frost wedging in the winter
