crownedrose:

I talked about ductile deformation two days back, and now this is a post about brittle deformation. Brittle deformation differs from ductile deformation easily when you look at the rocks. Ductile looks as if someone has taken the rock, made it into gum, and then stretched it to make it curve, fold, etc. Brittle deformation is like taking a sledgehammer and fracturing the rock, making it have fault lines and look like puzzle pieces waiting to be put back together.

Like ductile deformation, brittle deformation is also caused by stress. The main differences for these two kinds of deformations is temperature, pressure, rock composition, and deformation rate. Higher temperatures and pressures are affiliated with ductile deformation whereas lower temperatures and pressures usually create brittle deformations.

This is a photo I found on geoscience.wisc.edu while looking for a good photo via google. I looked at a lot of different photos showing characteristics of brittle deformation, but this one I enjoyed the most because you can clearly see where the rock has been shifted, creating those faults. With banding like in the photo above, it helps you easily see where the stress hit the rock, creating these fractures.