There was an interesting rock formation in the wall of the Lafarge quarry yesterday. Well, at least interesting to me. Then again, I was raised by a geologist which meant a certain amount of interest in rocks rubbed off. Anyway, I took the following image with my digital camera and later sent a copy of it to Papicito (a.k.a. my father) to ask what the diagonal structure was.
He sent back the image with his interpretation of the structure added to the image!!!
I had to ask both my father and Wikipedia to understand what a Diabase dyke was, but at least I will go to bed less stupid than I got up. "A dyke or dike is an intrusive igneous rock that cuts across the pre-existing structures, in this case the horizontally stratified limestone. A sill would have followed the stratification."
Got that? From this I am guessing that there is also a sill in this structure that seems to be at a geometric angle to the dyke.
What a time to be alive when we can toss around information like this!