The Test on Shaping Earth's Surface consists of 18 questions. Correct answers are found through links located at the end of each question.
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Question #1: Which of the following must occur before the others can take place?
(A). weathering
Weathering prepares the way for erosion by breaking solid rock into rock fragments. The fragments are then eroded, physically picked up by an agent such as a stream or a glacier. After they are eroded the materials are removed by transportation. Thus weathering must occur before erosion or transportation can take place. Exfoliation is a specific type of mechanical weathering that occurs in granite. Other types of weathering do occur and exfoliation is not necessary before erosion and transportation can take place.
Question #2: The red soils of Georgia and Oklahoma are one result of
(C). chemical weathering.
The ferromagnesian minerals contain iron, magnesium, and other metal ions in a silicate structure. Iron can react with oxygen to produce several different iron oxides, each with its own characteristic color. The most common iron oxide is hematite and has a deep red color. It is the presence of such iron oxides that color many sedimentary rocks and soils. The red soils of Georgia, Oklahoma, and other places are colored by the presence of iron oxides produced by chemical weathering.
Question #3: A cold, dry climate would probably result in mostly
(B). mechanical weathering.
Chemical weathering is the alteration of minerals by chemical reactions with water, gases of the atmosphere, or solutions. Mechanical weathering, on the other hand, is the physical breaking up of rocks without any changes in their chemical composition. Chemical change is slowed by cold, dry conditions and mechanical weathering is not so temperature dependent. Thus there is more mechanical weathering than chemical in a cold, dry climate.
Question #4: The roots of a tree grow into cracks and wedge the rocks apart as they grow. This is an example of
(C). mechanical weathering.
Mechanical weathering, is the physical breaking up of rocks without any changes in their chemical composition. The roots of trees and shrubs mechanically wedge rocks apart as they grow into cracks, exerting pressure on the walls of the crack and making it larger and larger as the root grows.
Question #5: A cavern in a limestone formation was probably produced by
(C). carbonation.
Carbonation is a reaction between carbonic acid and the minerals making up rocks. Rainwater is naturally somewhat acidic because it dissolves carbon dioxide from the air. This forms a weak acid known as carbonic acid, which is the same acid found in your carbonated soda pop. Carbonic acid rain falls on the land, seeping into cracks and crevices where it reacts with minerals. Limestone is easily weathered to a soluble form by carbonic acid and many limestones caves were produced by the chemical weathering of limestone by carbonation.
Question #6: An abundance of humus with balanced amounts of sand, silt, and clay would be found in
(B). topsoil.
A soil that has balanced amounts of sand, silt, and clay mixed with an abundance of humus is called loam. Loam is a great soil for gardening since it is fertile and well drained, yet holds enough moisture for sustained plant growth. Loam is usually found in the topmost layers of soil, so it is also referred to as topsoil. It is usually more fertile because it is closer to the source of humus, which is altered, decay-resistant organic matter.
Question #7: In general, deeper and richer soils should be found in which type of climate?
(C). wet and warm
In general, soils formed in cold and dry climates are shallower with less humus than soils produced in wet and warm climates. This happens because chemical reactions occur at a faster pace in warmer, wetter soil than they do in dry, cooler soil. Wet and warm climate is also more conducive to plant growth, which would provide more organic matter for the formation of humus.
Question #8: Which of the following is most effective in modifying the earth's surface?
(A). running water
Running water is the most important of all the erosional agents of gravity that remove rocks and rock materials to lower levels. Streams and major rivers are at work, for the most part, 24 hours a day every day of the year moving rock fragments and dissolved materials from elevated landmasses to the oceans.
Question #9: Rapids and waterfalls are characteristic features of a stream valley in a stage of
(A). youth.
The development of a stream channel into a widening floodplain seems to follow a general, idealized aging pattern. When a stream is on a recently uplifted landmass, it has a steep gradient, a vigorous, energetic ability to erode the land, and characteristic features know as the stage of youth. Youth is characterized by a steep gradient, a V-shaped valley without a floodplain, and the presence of features that interrupt its smooth flow such as boulders in the stream bed, rapids, and waterfalls.
Question #10: Flooding is more common in a stream valley that is in a state of
(B). old age.
The development of a stream channel into a widening floodplain seems to follow a general, idealized aging pattern. Old age is marked by a very low gradient in extremely broad, gently sloping valleys. The stream now flows slowly in broad meanders over the wide floodplain. Floods are more common in old age since the stream is carrying a full load of sediments and flows sluggishly.
Question #11: You should expect more old age features where a stream
(A). flows into the ocean; at its mouth.
Streams and rivers are dynamic systems that respond to local conditions, so it is possible to find an "old age feature" such as meanders in an otherwise youthful valley. In general, old age characteristics are observed near the mouth of a stream where it flows into an ocean, lake, or another stream. Youthful characteristics are observed at the source, where the water collects to first form the stream channel. As the stream slowly lowers the land, the old age characteristics will move slowly but surely toward the source.
Question #12: Today, glaciers cover about what percent of Alaska?
(D).less than 3%
Today, the most extensive glaciers in the United States are those of Alaska, which covers less than 3 percent of the state's land area.
Question #13: A ridge-like glacial deposit is the
(A). moraine.
A glacier does its erosional work by bulldozing, abrasion, and plucking. Bulldozing is the pushing along of rocks, soil, and sediments by the leading edge of an advancing glacier. Deposits of bulldozed rocks and other materials that remain after the ice melts are called moraines.
Question #14: A U-shaped mountain valley was most likely formed by a (an)
(B). glacier.
As an alpine glacier moves downhill through a V-shaped valley the sides and bottom of the valley are eroded wider and deeper. When the glacier later melts, the V-shaped valley is now a U-shaped valley that has been straightened and deepened by glacial erosion.
Question #15: A mountain stream with gray to blue-gray water from suspended silt is most likely a result of
(B). glacial erosion.
A glacier does part of its erosional work by abrasion, which occurs as rock fragments frozen into the moving glacial ice scratch, polish, and grind against surrounding rocks at the base and along the valley walls. One result of this abrasion is the pulverizing of rock into ever finer fragments, eventually producing a powdery, silt-sized sediment called rock flower. Suspended rock flower in meltwater from a glacier gives the water a distinctive gray to blue-gray color.
Question #16: The landscape is most likely to have sharp angular outlines in which type of climate?
(C). dry, cool
Chemical weathering is more dominant in warm, moist climates and mechanical weathering is more dominant in dry climates. Thus, landforms in warm, moist climates tend to have softer, rounded outlines from the accumulation of clay minerals, sand, and other finely divided products of chemical weathering. The landforms in dry climates, on the other hand, tend to have sharp angular outlines from the mass movement of rock materials from vertical cliffs. Lacking as much chemical weathering, the landscapes in dry climate regions tend to have sharper outlines.
Question #17: Which of the following is more highly acidic?
(A). grapefruit
Pure, unpolluted rain is naturally acidic. Carbon dioxide in the atmosphere is absorbed by rainfall, forming carbonic acid with a pH in a range of 5.6 to 6.2, compared to the pH of 7 for pure water. The pH of what is generally recognized as acid rain is even lower, made more acidic by the addition of exhaust emissions of sulfur and nitrogen oxides. Acid rain generally has a pH range of 4.0 to 5.5. Oranges and grapefruit are more acidic than acid rain, with grapefruit being more highly acidic with a pH in the range of 3.0 to 3.2. Nonetheless, acid rain does make a detrimental environmental impact on lakes, forest, crops, materials, and human health. It does not take a very high acidity to be damaging and acid rain with the acidity of grapefruit juice would be even more damaging.
Question #18: Increased CO2 would probably increase which type of landscape feature?
(A). caves in limestone
There might be weather changes brought about by increased CO2 -- such as the greenhouse effect -- that might cause changes in the desert, mountains, or coastal regions, but CO2 plays a more direct role in the formation of limestone caves. Rainwater is acidic because it dissolves carbon dioxide from the air, forming the weak acid known as carbonic acid. More CO2 to dissolve in rainwater might mean more acid, which would increase the weathering of limestone by carbonation.
