Question

Which one of the following statements correctly describes how stream terraces can form? Group of answer choices A temporary base level is eliminated; the stream aggrades its channel upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream. A temporary base level is eliminated; the stream downcuts upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream. Base level drops; the stream aggrades its channel, and the former floodplain is left below the present elevation of the stream. Base level rises; the stream downcuts, and the old floodplain is left well above the elevation of the present-day channel.

Answer 1

Answer: A

Explanation: A stream terrace basically forms through this process– Temporary base level is eliminated; the stream downcuts upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.

Answer 2

Answer:

A temporary base level is eliminated; the stream downcuts upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.

Explanation:

The formation of steam terraces occurs when streams move down into floodplains, leaving behind some remnants of older floodplain as steps in the form of benches along the valley sides. A temporary base level is eliminated; the stream downcuts upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.