siltstone - teaching student specimens of a Miocene siltstone from the Ridge Basin, California UNIT OF 5 SPECIMENS

This siltstone is Miocene in age, is moderately lithified, and was deposited in a closed basin in a non-marine or brackish marine depositional environment. It is mapped as a unit the Ridge Route Formation, part of the Ridge Basin Group. The cement is calcium carbonate which will effervesce with a drop of dilute hydrochloric acid. These are well-enough cemented that they will withstand student examination.

The silt grains in these specimens are smaller than those of a sandstone and and feel gritty when rubbed.  It would be instructive to compare this siltstone with one that is cemented with silica, and with a sandstone. 

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