13. In the picture above, when Dr. Alley slices his finger through the sand, he is recreating on a smaller scale what type of geologic process?A) The action of waves making a beach in Hawaii.B) The action of mass wasting, as soil and rock collapses off of newly steep canyon walls initially carved out by water.
C) The action of an earthquake tearing apart continents.D) The action of Chuck Norris karate chopping someone.E) The action of earthworms burrowing in loose soil.Feedback: Despite any passing resemblance, Dr. Alley is not using martial-arts techniques to extract money from sand. Instead, he is showing how a river carves a canyon, which then widens as mass wasting occurs on the steep new walls.Table for Individual Question FeedbackPoints Earned: 1.0/1.0 Correct Answer(s):B14. In the photo above, Sam Ascah is standing on sand and gravel in a pothole, where a stream swirlsduring the short but intense thunderstorms of Zion National Park. And next to that stream, the other picture shows the sandstone and the hang-on-so-you-don't-fall-over-the-cliff chain along the trail. A likely interpretation of these features is:it would look cute and slide well, and they cut the potholes so that hikers would have something to look at.
cut the notches behind the chain.hikers grabbed it, and the potholes were cut by water swirling rocks around during the rare floods over much longer times.The chain really has hung there for decades, and has been scraped against the cliff dozens of times per day each summer, slowly wearing into the easily broken sandstone. The stream does swirl rocks around and slowly wear down the potholes. The potholes were there beside the cliff when the trail was established, and haven’t changed too much over decades.Table for Individual Question FeedbackPoints Earned: 0.0/1.0 Correct Answer(s):C15. Dr. Alley once helped a Grand Canyon ranger answer a tourist’s question: "Why is the Canyon wider at the top than at the bottom?" The tourist had their own favorite theory. Based on the materials that have been presented to you’vein this class, what geologically accepted answer would Dr. Alley and the ranger have given the tourist?“optical illusion” of distant things appearing smaller causes it to look as if the canyon is narrowing downward.the river has narrowed as the drying occurred, and now cuts only a narrow canyon.creep or flow into the river to be washed away, thus widening the canyon above the river.running slowly (a little tap feeds a big bathtub…); then, as the Rockies were raised, the river steepened and narrowed, so it used to cut a wide canyon and now cuts a narrow one.
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- Correct Answer, Individual Question, Dr. Alley