Forams in Dewey Limestone

Forams in Dewey Limestone with TrL and CL. CL image is much sharper than TrL image because CL is generated from a thin layer near the surface, whereas the TrL image is averaged over the full 30 micron sample thickness. Typical conditions are 8 kV and 0.3 mA, unfocused beam. Digital camera exposure time is less than a second.