Question 1

Which of the following is most resistant to both chemical and physical weathering?

Accepted Answer

Quartz is the most resistant to both chemical and physical weathering among the given options. It is a hard mineral and does not react chemically with water or air, which makes it very resistant to weathering. Clay minerals and limestone are susceptible to chemical weathering, and granite is susceptible to physical weathering due to the high quartz content creating fractures with expanding and contracting temperatures.

Question 2

The finely divided,red,brown,and yellow soil-coloring minerals originate by what process?

Accepted Answer

The finely divided, red, brown, and yellow soil-coloring minerals are primarily iron oxides that precipitate during the chemical weathering process. This process often occurs in soils that have been influenced by water and air over a long period, which results in the breakdown of primary minerals like quartz and feldspars. Iron oxides then form as a product of this breakdown, giving the soil its characteristic color.

Question 3

Rounding of angular edges of rock outcropping and formation of insitu,spherical boulders are both indications of ________.

Accepted Answer

Rounding of angular edges of rock outcroppings and formation of insitu, spherical boulders are both indications of chemical weathering and associated spheroidal weathering. This type of weathering occurs generally in granular rocks, like sandstone or in rocks that are composed of many different minerals.

Question 4

Which one of the following is an important,mechanical weathering process for enlarging fractures and extending them deeper into large boulders and bedrock?

Accepted Answer

Frost wedging, which occurs when water freezes in cracks and expands, is an important mechanical weathering process for enlarging fractures and extending them deeper into large boulders and bedrock. This can eventually lead to the breakdown of the rock into smaller pieces.

Question 5

Centuries ago quarrymen learned that when quarrying granite it was usually easiest to break the rock along a nearly horizontal surface.We now know this arises because ________.

Accepted Answer

Uplift and exhumation of granites produces an unloading, which causes the formation of sheeting joints. These sheeting joints are nearly horizontal fractures that make it easier to break the rock in a quarry.

Question 6

In which area would weathering by frost wedging probably be most effective?

Accepted Answer

Frost wedging is most effective in moist, temperate climates where there are frequent freeze-thaw cycles.

Question 7

What two factors speed up rates of chemical reaction and weathering in rocks and soils?

Accepted Answer

Warm temperatures and high moisture levels increase rates of chemical reaction and weathering in rocks and soils.

Question 8

Under similar warm,moist climatic conditions,why would basalt and gabbro generally have higher chemical weathering rates than rhyolite and granite?

Accepted Answer

Basalt and gabbro contain more ferromagnesian minerals (such as olivine and pyroxene) than rhyolite and granite, which are rich in feldspars and quartz. These ferromagnesian minerals are more susceptible to chemical breakdown through oxidation and other chemical processes, leading to higher rates of chemical weathering in basalt and gabbro compared to rhyolite and granite.

Question 9

Assume that water filling a crack in a rock undergoes cycles of freezing and melting.Which of the following statement is true?

Accepted Answer

When water freezes, its volume expands and creates pressure on the walls of the crack. As this process repeats, the pressure builds up and can cause the crack to widen or even split apart. Therefore, water expands as it freezes, causing the crack walls to be pushed apart.

Question 10

Mass wasting,a process that often occurs between weathering and erosion,involves ________.

Accepted Answer

Mass wasting involves the downward movement of rock and soil by gravity. This process can occur due to a variety of factors, including the angle of the slope, the type of material involved, and the presence of water, among others. Unlike erosion, which involves the transport of material by water, wind, or ice, mass wasting typically involves the movement of material downslope without any external agents.

Question 11

What is the major distinction between internal and external Earth processes?

Accepted Answer

The major distinction between internal and external Earth processes is that internal processes involve processes like Plate Tectonics, which are driven by heat and occur inside the Earth's crust, whereas external processes are driven by energy from the Sun and occur outside the Earth's crust.

Question 12

One important relationship between chemical and mechanical weathering is ________.

Accepted Answer

Mechanical weathering breaks down rocks into smaller pieces, which increases their surface area. This increased surface area provides more opportunities for chemical weathering to occur.

Question 13

Clay minerals formed from gabbro or diorite bedrock illustrate which kind of weathering?

Accepted Answer

Clay minerals formed from gabbro or diorite bedrock indicate chemical weathering. This type of weathering involves the breakdown or decomposition of minerals through chemical reactions, such as oxidation or hydrolysis.

Question 14

All of the following are factors that affect rates of weathering except for ________.

Accepted Answer

The geologic age of earth materials does not have a direct impact on rates of weathering. The other factors listed (rock characteristics, surface area, and climate) all play a role in the rate at which weathering occurs.

Question 15

Which one of the following statements concerning mechanical weathering is not true?

Accepted Answer

Mechanical weathering involves physical processes that break down rocks into smaller pieces, but it does not result in a major change in the mineral composition of the weathered material. Chemical weathering, on the other hand, can alter the mineral composition of rocks by dissolving or transforming certain minerals.

Question 16

Which of the following is not a physical weathering process?

Accepted Answer

Rocks reacting with organic acids from plants is a chemical weathering process, not a physical one. Physical weathering processes are those that break down rocks without changing their chemical composition, whereas chemical weathering processes involve changes to the chemical makeup of the rock. Frost wedging, salt crystallization, and tree root growth are all examples of physical weathering processes.

Question 17

Chemical weathering rates are highest in ________.

Accepted Answer

Chemical weathering is accelerated by the presence of water, so hot and wet climates have higher rates of chemical weathering than hot and dry or cold and dry climates. Cold and wet climates can also have high rates of chemical weathering, but they are generally slower than in hot and wet climates.

Question 18

Which one of the following statements best describes erosion?

Accepted Answer

Erosion is the process by which weathered rock and mineral particles are removed from one area and transported elsewhere. Option A describes weathering, Option B describes mass wasting, and Option D describes specific processes within erosion (leaching and eluviation).

Question 19

Which of the following best describes sets of fractures in relatively fresh bedrock,such as granite,that are roughly parallel to the land surface?

Accepted Answer

Sheet fractures are sets of fractures in fresh bedrock that are roughly parallel to the land surface. They are caused by expansion due to the release of confining pressure as overlying rock is eroded. Thermal expansion cracks are caused by temperature changes, hydrolytic failures are caused by chemical reactions, and columnar joints are formed in lava flows.

Question 20

Frost wedging is the major weathering process contributing to the formation of which regolith material?

Accepted Answer

Frost wedging is the mechanical weathering process that occurs when water seeps into cracks in rocks or soil, freezes and expands, causing the rock to break apart. This process is most often seen in cold, high-altitude areas and is a significant contributor to the formation of talus slopes, which are large piles of broken rock fragments. Therefore, the correct answer is B, talus slopes.

Quiz 4: Weathering, soil, and Mass Wasting