5  - The first Radiolarian Chert outcrop
 
 
Our first look at the silica rich rocks in the sequence.  Older than the overlying sandstone and shale layers this exposure has alternating layers of hard, silica with layers of weak and erodable shale.  As the shale is removed by erosion the alternating layers become quite prominent.

The hard resistant layers are a rock called chert that was created by the deposition of silica on the ocean floor.  A majority of the silica, we believe, comes from the skeletons of microscopic, ocean animals called Radiolarians.

Further information on Radiolarian Chert

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