What is Soil (and Why is it Important)?: Crash Course Geography #17

What was the primary cause of the Aral Sea shrinking significantly?

• Natural climate change causing increased evaporation.

• Overfishing and pollution from nearby cities.

• Diversion of river water for irrigating crops like cotton and rice.

• A large earthquake that drained the sea into underground caverns.

Which of the following is NOT listed as one of the four main components of soil?

• Minerals

• Organic Material

• Air

• Rocks

What is 'parent material' in soil, and what does it primarily determine?

• It is the organic matter that supplies nutrients, determining soil color.

• It is the rocks broken down by natural forces, determining soil texture and structure.

• It is the water content in the soil, determining how much plants can absorb.

• It is the air pockets in the soil, determining how much oxygen is available.

What is the 'O Horizon' in a soil profile mainly composed of?

• Topsoil with many nutrients.

• Coarse sand and silt.

• Humus (organic material).

• Accumulated leached minerals.

What is the lowest layer of the soil profile, made of unbroken parent material or bedrock, called?

• O Horizon

• C Horizon

• R Horizon

• A Horizon

What percentage of farmlands worldwide are losing their topsoil faster than new soil can form?

• About 15 percent

• About 25 percent

• About 35 percent

• About 50 percent

In tropical rainforests, what is the "brick-like" soil called that forms from laterization and is mostly a hardened B horizon made of iron-rich clay?

• Podzol

• Caliche

• Laterite

• Topsoil

In climates where grasses thrive and there isn't much moisture for trees, what is the hard layer of calcium carbonate that forms in the B horizon called?

• Laterite

• Podzol

• Caliche

• Bedrock