Aerial portraits of the American West: photographs by John Shelton.

A GEOLOGIST FILLED with a love for music and machines, John Shelton is best known for his pioneering aerial photography. Unlike most aerial photographers, however Shelton mostly flew alone and never had the luxury of using a viewfinder. He maneuvered his low-winged plane to align his large-format camera through a small, open window to optimize the angle, lighting, and composition of each geologic feature. Originally, his exposures were made with a handheld light meter, but eventually he determined his camera settings from experience.

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Shelton's love and knowledge of flying enabled him to reveal geologic features and processes through his aerial photographs of wondrous landscapes. 'The oblique aerial view of most of Shelton's photos offers a useful perspective that neither a ground view nor a high-altitude view can provide. A geologist, teacher, and pilot, Shelton wanted to make pictures that would be as informative as they were inspirational. The beauty of his photos reveals the eye of an artist, yet there is a geological lesson to be learned from every one," notes a 1994 article in Earth magazine.

A graduate of Pomona College, Claremont, Calif., with a bachelor's degree in math and music, and formerly an associate professor of geology at Pomona, Shelton always has been intensely interested in the process of learning. He received his Ph.D. in geology from Yale University, New Haven, Conn., during which time he worked for the government doing research, which then was used for his dissertation. For 12 years, he served as geology consultant for Encyclopedia Britannica educational films.

In 1993, Shelton received the American Geological Institute Legendary Geologist Award for "Outstanding Contribution to Public Understanding of Geology." He also authored Geology Illustrated, a comprehensive textbook lavishly illustrated with his aerial photos. In 1999, Geology Illustrated was chosen as one of the top 100 science books of the 20th century by American Scientist magazine.

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"Geology Illustrated was first published in the late '60s, while I was in graduate school," says Michael Hager, president and CEO of the San Diego Natural History Museum. "It was exceptional then and a classic now. Today's skies are not clear enough to create these wonderful images. John Shelton, at 94 years young, [now] has produced these incredible images in museum size and quality and they are still the best illustrations of geologic processes available."

Images by this pioneering geologist and photographer are on public display for the first time, through Nov. 2, at the San Diego (Calif.) Natural History Museum.