Mark Klett is an American Photographer and Professor of Art at Arizona State University. His work studies Western landscapes, most notably the Grand Canyon and desert environments. Klett has a diverse background in geology and photography. After receiving a bachelor's degree in Geology, he decided to pursue photography professionally and received an MFA in Photography. In the meantime, he spent summers using his geology degree as a field assistant for the U.S. Geological Survey. He uses a technique called "re-photography" or "repeat photography", by stitching photographs of particular locations into present-day photographs of the same location (see images).
Klett taught a class at Anderson Ranch, titled Photographing the Passage of Time. Klett's work can be seen on his website.
More information on Anderson Ranch and workshops, can be found here.