Answer:
Often, waterfalls form as streams flow from soft rock to hard rock. This happens both laterally (as a stream flows across the earth) and vertically (as the stream drops in a waterfall). In both cases, the soft rock erodes, leaving a hard ledge over which the stream falls.
Explanation:
Other Waterfall Facts:
Without similar protection, the next pool down began to erode, forming a vertical wall between the two—and thus, a waterfall. What's more, Crosby notes, these waterfalls lingered. Each lab-made cascade stuck around for about 20 minutes, a period of time that represents 10 to 10,000 years, according to the study
If the sun were to stop shining, then all the waterfalls in the world would eventually stop. It is the sun which provides all of the energy needed to lift water from the ocean to the head of the river valley so that waterfalls can continually have water falling over them.
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-RosemaryAndStars