Geology Chapter 5 Summary

What is mechanical weathering?

The physical disintegration of rocks into smaller pieces with little or no chemical change.

What is exfoliation?

The process of spalling off rock layers or peeling layers from larger rock formations.

What are exfoliation domes?

Large rounded landforms developed in massive rocks like granite by exfoliation.

Define weathering.

The process that changes the physical and chemical character of rocks.

What is erosion?

The picking up or physical removal of rock particles by agents like running water or glaciers.

What is transportation in geology?

The movement of eroded particles by agents such as rivers, waves, or glaciers.

What is frost action?

The mechanical effect of freezing water on rocks, commonly known as frost wedging.

What does pressure release refer to in geology?

The reduction of pressure on a rock body that causes it to crack as it expands.

What is spheroidal weathering?

Weathering that rounds off rock corners and edges more rapidly than smooth rock faces.

What is differential weathering?

The tendency for different types of rock to weather at different rates.

What is chemical weathering?

The decomposition of rock from exposure to water and atmospheric gases, resulting in new minerals.

Define carbonic acid in relation to weathering.

A weak acid formed from water and carbon dioxide that is most effective in chemical weathering.

What mineral forms clay minerals when chemically weathered?

Silicate minerals.

What mineral is most resistant to chemical weathering?

Quartz.

Define residual soil.

Soil that develops from the weathering of the bedrock beneath it.

Define transported soil.

Soil that does not develop from locally formed rock but from rocks brought from other regions.

What are soil horizons?

Soil layers that are distinguished by their appearance and chemical composition.

What is the most important factor determining soil type?

Climate.

What factors affect soil type?

Parent material, time, slope, organic activity, and climate.

What influences rates of erosion?

Soil characteristics, climate, slope, and vegetation.

What are the soil horizons?

O, A, E, B, and C.

What is the composition of the O horizon?

Consists entirely of organic materials such as decomposed leaves and animals, may contain humus.

How does the O horizon form?

Forms from the accumulation and decomposition of organic matter at the surface.

What is the composition of the A horizon?

A mixture of organic material from the O horizon and minerals from the weathered rock below.

How does the A horizon form?

Forms through interaction of weathering, organic matter deposition, and biological activity.

What is the composition of the B horizon?

Accumulated minerals (iron, aluminum, clay) leached down from the A and E horizons.

How does the B horizon form?

Forms through a process called illuviation, where materials leached from above accumulate.

What is the composition of the C horizon?

Partially weathered rock or unconsolidated material that has not been affected, lacking organic material.

How does the C horizon form?

Formed directly from physical and chemical weathering of bedrock.