<u>Answer</u>: e) Volcanic activity in the region leaves behind valuable minerals.
<u />
<u>Explanation</u>: Volcanic activity has played an important role in the creation of the Cascade Mountains as they were originally created through the subduction of two continental plates.
It is well known that gold deposists are often found through volcanic systems. Water heated by volcanoes will become very acid and thus dissolve surrounding rocks. This water that will contain gold and other metals will then follow fractures through the bedrock towards the surface. In time, these will turn into gold veins or lodes.
