Oil Slick

When we moved here, I dug a fire pit and lined it with creek rock.   Some of the rocks were beautiful blue things.   When we lit the fire, the blue rocks exploded.

Oil shale.

It's all over here.   After a good rain, when the creek bottom is scrubbed clean, it's blue.  It's really pretty.

And when the weather is wet, we get little oil slicks in places where the water collects off a hill or in a bog.