Author Question: The Jurassic Period of geologic time was an interval marked by a great number of glacial ... (Read 59 times)

K@ · **on:** Aug 7, 2018

The Jurassic Period of geologic time was an interval marked by a great number of glacial fluctuations that began about 2.6 million years ago and ended around 10,000 years ago.
a. True
b. False
Indicate whether the statement is true or false

Question 2

How do alluvial fans form?

tkempin · **Reply #1 on:** Aug 7, 2018

Answer to Question 1

False

Answer to Question 2

Where ephemeral, intermittent, or perennial streams flow out of narrow, constricting, upland canyons onto the less confining, open lowland plains, the channels become wider and shallower, causing them to slow. The decrease in velocity reduces the stream's competence and its capacitythat is, the size and amount, respectively, of load it can transportthus causing deposition. As velocity continues to decrease, the sediment carried and deposited decreases in size. As the stream begins to build a fan it also shifts laterally around deposited clasts and sediment, sweeping back and forth. In some cases, debris flows can build up fans rather than, or in addition to, stream action.