How do we know that the stream beds of Mars are relatively ancient?
A)There are islands in them
B)There are impact craters on their floors
C)The water in them is frozen solid
D)They all begin on the flanks of Martian volcanoes

Question

Quizplus · Accepted Answer

The presence of impact craters on the floors of the stream beds suggests that they have been preserved over a long period of time, indicating that the water flow is relatively ancient.

How Do We Know That the Stream Beds of Mars