Monday, December 03, 2007

Geology Post : 12-3-07

This photo comes from my field work in 1999. It is in the top 5 cool geology pictures I have. Though the picture quality sucks, the geologic principal is stellar.

The rock is a pelitic schist. The two veins are quartz.

The interesting things to note are that one quartz vein (down from upper left to lower right) is pretty much unchanged. This represents a 'zone of flattening'.
The other quartz vein (the squiggly one; down from upper right to lower left) is within a 'zone of compression'. It demonstrates the direction of compression oriented between approximately N18-40 E.
Which fits in with the regional geology of south western Maine very well.

Teachers, feel free to use in class. Questions? Comments?


  1. I have a really cool post on my Blog from last year... check it out! It is dated 08/30/06

  2. ... a hard hat and boots. I am also wearing a safety harness, so that if I pass out from something I won't fall down. It makes it harder to get someone out of the hole when they're hunched over... seriously! I've only heard of one "geologist" accident down hole logging, in my 13 years of experience. A geologist got hit in the head by a rock and went temporarily blind. He was wearing a hard hat, too! I've also met a driller who actually fell into a 120 foot hole and lived to tell the story.

  3. Hmmm, very interesting. Would I be correct (probably not) in saying that the fold vergence can be used to determine the direction of maximum pressure? I noticed they seem to verge top to the left.

    Also, what branch of geology do you study?

  4. 1&2 I studied structural geology.
    I think that in the case I posted the fold vergence is not clear. The foliation is also not visible in the photo.

    The solid evidence of stress direction is the flat undeformed vein and the shortened vein. Short by about 60% if i remember correctly.