If a stream crosses a strike-slip fault without changing its course, what can be concluded?

Choosing the conclusion that the fault movement occurred after the stream crossed is valid because strike-slip faults are characterized by lateral movement along the fault line. If a stream crosses such a fault without any noticeable change in its course, it suggests that the stream's position was established before the fault experienced movement. Therefore, the fault must have moved after the stream's original path had already been formed.

In a scenario involving an active strike-slip fault, one would expect to see some evidence of displacement or alteration in the stream's path if the fault had moved prior to or concurrently with the stream's development. Since the stream remains unchanged as it crosses the fault, it provides strong evidence that any significant fault movement occurred post-establishment of the stream's course.