And clay deposits bury our diatoms. Over time the pressure of 500 meters of overlaid clay compresses our field of diatoms into a crystalline mass. One day we will call it chert. Chert's crystals are small, chert contains some water, chert behaves much like a glass. The land will rise and streams will push through the clays, boring down, cutting channels, washing and tumbling and breaking the chert into small, round stones.
Geological time seems to have no end.
The silica from our granite, now chert, will be reburied and recompressed in a bed of limestone, CaCO 3 . Over time the chert will become what we call flint. About 8,000 years ago, a man walked along another stream in what is now Washington State. One day we will call that water the Columbia River. The man picked a round, black stone from a limestone cliff along the stream.