Weathering and Soils

EES 101

What is the difference between weathering and erosion?

Weathering is the physical breakdown and/or the chemical alteration of rocks. Erosion is the removal of weathered materials.

How does mechanical weathering differ from chemical weathering?

Mechanical weathering is the dis-aggregation of rocks via mechanical processes. Chemical weathering is the decomposition of rocks and minerals via chemical reactions.

What is Eroded material called?

Sediment

What is Frost Wedging?

It is a type of mechanical weathering where the water expands within a rock when it freezes. It is caused by the repeated freezing and thawing cycle of water in extreme climates.

What is Unloading?

It is mechanical weathering through uplifting, expanding, and weathering. The rocks get exfoliated due to a reduction in confining pressure.

What is thermal expansion?

It is a type of mechanical weathering where the rock expands and cool due to heating and cooling. It happens in climates like deserts with extreme daily temperatures.

What is biological activity?

It is a type of mechanical weathering where disintegration occurs due to plants and animals. Ex. Root Wedging.

what is the most important agent in chemical weathering?

Water

What is dissolution?

It is a type of chemical weathering where minerals are dissolved in water. Ex. Halite, Gypsum, and Calcite. Acid rain enhances this.

Which weathering process forms caves?

Dissolution

What is oxidation?

It is a type of chemical weathering where iron and oxygen create rust.

What is hydrolysis?

It is a type of chemical weathering where minerals react with water to form other products.

What happens when granite is weathered?

The K-feldspar turns into kaolinite or clay.

What acid chemically weathers Limestone caves?

Carbonic acid

How does surface area affect the weathering rate?

Chemical weathering increases with the surface area.

How do rock characteristics affect the weathering rate?

Rocks and minerals have different resistances to atmospheric processes. Calcite rocks (marble and limestone) dissolve in acidic solutions. More unstable minerals decompose quicker.

How does the climate affect the weathering rate?

Higher weathering occurs in warmer and more humid climates.

What is soil?

It is layers of loose mineral and organic matter with water and air.

What is regolith?

They are rock and mineral fragments found in soil.

What is humus?

It is decayed animal and plant remains in soil. They are small, but essential components.

What is the O Horizon?

It is the first layer in soil, it is made of organic matter. It makes up the topsoil.

What is the A horizon?

It is the second layer of soil. It is made of organic and mineral matter. It makes up the topsoil.

What is the E Horizon?

It is the third layer of soil. It has little organic matter and is the zone of leaching.

What is the B horizon?

It is the fourth layer in soil. It is the zone of accumulation and makes up the subsoil.

What is the C horizon?

It is the last layer of soil. It is made of partially altered parent material.

What are the five factors of soil formation?

Parent material, time, climate, plants and animals, and topography.

What is soil taxonomy?

The groups that have been established using common characteristics of soil. There are over 1000 soil types.

What is Pedafler?

They are soil with aluminum and iron in temperate climates with leaching.

What is Laterite?

They are soil rich in aluminum and iron in tropical climates with extreme leaching.

what is pedocal?

They are soil with calcium in dry climates with little leaching.