4.2 Soil formation + Erosion

Students want to determine the impact of soil erosion from the development of new housing. They plan to measure the density of a species of algae growing along the bottom of a river that flows through their town. The town is built in a heavily forested area, but a large area of trees along the river was recently clear-cut to allow for the construction of a new housing development, which has caused exposed soil to wash into the river. The river flows north to south through the town and is still forested both up- and downstream of the town.

Which of the following would be the best control sample for the study?

A) A sample of water collected just downstream of the southern forest

B) A sample of water collected just downstream of the housing development

C) A sample of water collected just downstream of the northern forest

D) A sample of distilled water

C) A sample of water collected just downstream of the northern forest

WHY is it C? A water sample collected from just downstream of the northern forest has not been contaminated by runoff from the construction project, since it is upstream from the construction site, and therefore would be less subject to erosion from the clear-cut area of forest

Students want to determine the impact of soil erosion from the development of new housing. They plan to measure the density of a species of algae growing along the bottom of a river that flows through their town. The town is built in a heavily forested area, but a large area of trees along the river was recently clear-cut to allow for the construction of a new housing development, which has caused exposed soil to wash into the river. The river flows north to south through the town and is still forested both up- and downstream of the town.

Which of the following explains the variable that would be the best for students to measure to determine the direct impact of soil erosion caused by the construction project on the river?

A) Water temperature, because a decrease in shading in the area would indicate an increase in soil erosion.

B) Nutrient levels, because a decrease in nitrogen and phosphorus would indicate an increase in soil erosion.

C) The pH level, because an increase in pH would indicate an increase in soil erosion.

D) Turbidity, because a decrease in water clarity would indicate an increase in soil erosion.

D) Turbidity, because a decrease in water clarity would indicate an increase in soil erosion.

WHY IS IT D? Soil erosion would directly increase the suspended and dissolved particulates in water, leading to an increase in turbidity and a decrease in water clarity. This would indicate that there is more soil erosion as a result of the construction site.

Students want to determine the impact of soil erosion from the development of new housing. They plan to measure the density of a species of algae growing along the bottom of a river that flows through their town. The town is built in a heavily forested area, but a large area of trees along the river was recently clear-cut to allow for the construction of a new housing development, which has caused exposed soil to wash into the river. The river flows north to south through the town and is still forested both up- and downstream of the town.

Which of the following is the dependent variable in the study?

A) The tract of land that was clear-cut for the housing development

B) A tract of land in a heavily forested area outside of town

C) The density of a species of algae growing along the bottom of the river

D) The flow rate of the river from north to south

C) The density of a species of algae growing along the bottom of the river

Which rock is formed at high temperatures and pressures?

A) Sedimentary 

B) metamorphic

C) igneous

D) sandstone

B) Metamorphic 

When sedimentary, igneous, or other metamorphic rocks are subjected to high temperatures and pressure, the resulting rock that is formed is metamorphic.

Whiuch statement is the best explanation of acid precipitation?

A) Acid precipitation causes chemical weathering, which can consume key soil nutrients from breaking up rock

B) Acid precipitation causes physical weathering, which can consume key soil nutrients from dissolving minerals in rock

C) Acid precipitation causes physical weathering, which can release key soil nutrients from breaking up rock

D) Acid precipitation causes chemical weathering, which can release key soil nutrients from dissolving minerals in rock

D) Acid precipitation causes chemical weathering, which can release key soil nutrients from dissolving minerals in rock

When carbon dioxide in the atmosphere dissolves in water vapor it creates carbonic acid, which can result in Acid Precipitation. For example, when feldspar—a primary mineral found in granitic rock—is exposed to natural acids in rain, it forms clay particles as a secondary mineral and releases ions such as potassium, an essential nutrient for plants.

What are the five primary soil formation factors?

A) parent material, climate, pH, latitude, altitude

B) climate, parent material, topography, organisms, time

C) parent material, topography, organisms, time, latitude

D) climate, parent material, pH, organisms, topography 

B) climate, parent material, topography, organisms, time

All of these factors combine to determine the formation, types and properties of soils.

Which is the correct order of soil horizons starting at the surface?

A) O, A, E, B, C

B) A, B, C E, O

C) O, A, B, C, E

D) O, E, A, B, C

A) O, A, E, B, C

*E is between A + B

What type of soil would be best to add to the bottom of a constructed pond, where the goal is to have as little leakage of water as possible?

A) mostly silt

B) equal amount of sand, silt, and clay

C) Mostly Sands

D) mostly clay 

D) mostly clay

The particles of a mostly clay soil are very small and have a high water holding capacity, reducing the soil's permeability, or rate at which water will flow through it.

Which of the following if added to soil would lower the base saturation?

A) sodium

B) magnesium

C) potassium

D) aluminum 

D) aluminum 

Because aluminum is considered a soil acid, its addition to the soil would decrease the soil's overall base saturation.

Using the soil texture triangle, what is the soil type that contains 30 percent clay, 30 percent silt, and 40 percent sand?

A) sandy loam

B) silt loam

C) aluminum

D) clay loam 

D) clay loam