How does the law of crosscutting explain the age of a fault?

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The fault is younger than the rocks above it.
The fault is younger than the rocks it cuts through.
The fault is older than the rocks above it.
The fault is older than the rocks it cuts through.

1 answer

The law of crosscutting relationships states that geologic features (such as faults and igneous intrusions) that cut through other rocks are younger than the rocks they disrupt. Therefore, in the context of your question, the correct statement is:

The fault is younger than the rocks it cuts through.