Soil Formation, Composition, and Properties - AP Environmental Science

Leaching occurs when percolating water transports materials from the top soil layers. Usually, these materials are illuviated(deposited) to a lower level.

All of these components make up soil. Differences in ratios of these components account for different soil types.

Soil categories are referred to as "horizons." Additionally, a vertical cross section of soil horizons is called a "profile."

Clay has the smallest particles, followed by silt, which contains larger particles than clay, but smaller particles than sand. Loam is a mixture of these three types of soil.

The correct response is soil. Soil is a mix of sand, clay, pebbles, and silt. It is the foundation of all our ecosystems.

The correct response is cohesion. This property measures how well a soil clumps together or breaks apart.

The correct response is permeability. This measure how quickly water can move through any substance - including soil.

The correct response is O Horizon. This O horizon is the layer closest to the surface - typically between the depths of 0 to 2 inches, and contains freshly fallen leaves, plant litter, and lots of other organic matter.

The correct response is B Horizon. The B horizon is referred to as the zone of accumulation because all the clay, minerals, and subsoil that is washed into it via illuviation from the overlying layers of soil. The B horizon is usually dark red or brownish due to the presence of clay and iron oxides.

Metamorphic rock is the only kind of rock that is formed below the Earth's crust. Igneous rock is formed by lava and volcanic activity. Sedimentary rock is formed by the collection of sand and other microscopic components that are fused together. Generally, the last two kinds of rock are found in the crust only, unless they are melted into lava.

There are six types of soil horizons and each has different chemical or physical properties. Each type of soil has a different number of horizons. The horizons start at the parent material (bedrock) and continue up to the surface.

The correct response is humus. This is one of the most important components to soil communities. Humus is formed as things like leaves, branches, and other vegetation breakdown (slowly) over time. Earthworms and microbes help speed up the process of breaking down dead organic matter into humus.

The O Horizon is composed of humus (organic matter), the A Horizon is a mixture of minerals and organic matter, the B Horizon is composed mainly of minerals and the D horizon is solid bedrock. The C Horizon best fits this definition, as it is the layer above the bedrock, consisting mostly of weathered rock fragments.

Leaching occurs when percolating water transports materials from the top soil layers. Usually, these materials are illuviated(deposited) to a lower level.

All of these components make up soil. Differences in ratios of these components account for different soil types.

Soil categories are referred to as "horizons." Additionally, a vertical cross section of soil horizons is called a "profile."

Clay has the smallest particles, followed by silt, which contains larger particles than clay, but smaller particles than sand. Loam is a mixture of these three types of soil.

The correct response is soil. Soil is a mix of sand, clay, pebbles, and silt. It is the foundation of all our ecosystems.

The correct response is cohesion. This property measures how well a soil clumps together or breaks apart.