The story started when sediments rolled down the side of a hill into a freshwater stream. After a long build up of sediments, they started compacting and later formed the rock known as siltstone. In this process some quartz might fall into the siltstone while it’s forming. That makes it pretty and shiny. This rock was probably formed in a stream on the island. It could have come from the Cascades... or a glacier that picked it u from a stream and then the glacier melted leaving the rock here.

This is some information we found about siltstone in part 1-2 of our rock project:

Siltstone is a very small grain sized sedimentary rock. It has a mohs of 3 (can be scratched by my fingernail) and has a brownish streak. It is very shiny even when there is not allot of light hitting it, which is from the bits of quartz and mica. It is rough, like fine sand paper. It is about 60% quartz, 30% mica, and 10% iron and other blackish sediments.