Monday, February 15, 2010

Shale

Any force that can shatter limestone can certainly have its way with soft shale. I’m speaking of the meteor strike and how it rearranged the bedrock of Blue Jay Barrens. Just over the hill from some major limestone outcroppings, we have this exposed bed of shale.

The shale was formed when layers of water sorted clay particles received enough pressure to consolidate them into hard layers. When formed, the layers were oriented horizontally. The meteor strike brought this section around to the vertical. Fractured shale layers arranged vertically makes it much easier for roots to penetrate.

Exposure to the elements results in a constant decomposition of the shale layers. There is a steady procession of chips, grains, and dust moving down the slope below the exposed shale.

Shale is a fascinating rock. Each layer is like a page of a book that can be turned to reveal new secrets. Some of the layers are quite soft and with a little effort can be worked and molded like the original clay from which it was formed. This is a shot of a small piece held in my hand.

This is another hand held piece showing layers that are hard and brittle and can’t be broken by hand. This piece contained a wide range colors and displayed some rusty spots that suggested the presence of iron. Near the center left of the photo there appears to be a small blue-bodied mite with red legs. I was so blinded by the snow while taking these shots that I could barely see the rock in my hand, let alone the mite. I didn’t see him until I downloaded these shots.

The soil here was formed from the shale. The result is a low pH soil with a fairly high clay content. Bedrock type dictates soil type; Soil type dictates plant growth; Plant growth dictates animal populations. What ever you are seeing on the surface is a direct result of what’s underground. To make sound land management decisions, you have to know what your foundation is made of.

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