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Practice Listening: Multiple Choice, Single Answer ID: #40091 Short Waterfalls
Instructions ›
You will see a video explaining the geological processes behind the formation of waterfalls. Listen to the recording and answer the multiple-choice question by selecting the correct response. Only one response is correct.

Transcript:

The definition of a waterfall can be seen here in Iceland. An abrupt, nearly vertical drop in this flowing river. This steep gradient has resulted from the differential erosion of the underlying riverbed. As the river wore its way through the area, it encountered dissimilar strata of rock. When the current eroded a less resistant layer, the more resistant rock beds remained, creating these steep drops. However, over longer geologic time periods, even these resistant rock layers will be eroded, the waterfall will be eliminated, and the smooth, upwardly concave profile of a mature river will result.

What causes the initial formation of waterfalls according to the video?

* Listen to the recording and select the correct answer

Result:

AI explanationShows the answer. Tap to open.
Option 2: "The differential erosion of underlying riverbeds"

Explanation: This option is correct as the text explicitly states that the steep gradient of the waterfall results from the differential erosion of the underlying riverbed. It describes how the river encounters different types of rock, leading to varying rates of erosion, which creates the waterfall.

Option 1: "The construction of artificial dams"

Explanation: This option is incorrect because the text does not mention artificial dams as a factor in the formation of waterfalls. The focus is on natural processes, specifically erosion, rather than human-made structures.

Option 3: "Sudden geological shifts or earthquakes"

Explanation: This option is incorrect because the text does not mention geological shifts or earthquakes as causes for waterfall formation. Instead, it emphasizes the gradual process of erosion over time.

Option 4: "The accumulation of large amounts of rainfall"

Explanation: This option is incorrect as the text does not attribute the formation of waterfalls to rainfall accumulation. The focus is on the erosion process rather than precipitation.

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