Some of our ongoing projects:
To calculate limestone weathering rates, we used a lidar scan of the 2000 year old Western Wall. The image to the left is a photo of a section of the wall, while the image to the right is a relief model derived from a scan of the same section. The Herodian wall was built from 2 different kinds of limestone, which resulted in some rocks eroding much quicker than others.
Our group is using atomic force microscopy to examine weathering mechanisms at ultra high resolution. The images show Solnhofen limestone before and after exposure to water. The dark regions are pits that form when tiny grains detach from the surface, and this is probably an important mode of limestone erosion.
We're also using our atomic force microscope to map the mechanical properties of shales with nano-scale resolution. The image to the left shows a backscattered electron image of kerogen (dark grey) containing bitumen inclusions (black). The elastic modulus map to the right shows that the bitumen is softer, weakening the kerogen structure.
Using environmental scanning electron microscopy we found that during water-shale interaction, pyrite grains - which often contain high concentrations of arsenic - become detached from the rock surfaces. We are currently determining if this is the dominant mechanism for the mobilization of arsenic in groundwater systems containing shales.