Part of a mastodon tusk weathering out of the Late Pleistocene Rogers Lake Beds in Death Valley National Park; image courtesy the book, Geological Story of Death Valley, by Dr. Thomas Clements (longtime professor of geology at the University of Southern California).

This is the very photograph that first fired my fascination with fossils in Death Valley. During my initial visit to Death Valley as a youngster, my parents had handed me Dr. Clements' book to peruse; one of the many photographs in that book was the black and white image seen above. And it immediately captured my imagination--here was a 15,000 -year-old mastodon tusk weathering out of ancient lake beds right there in supremely arid Death Valley! I kept asking my folks where in Death Valley the fossil might have come from, but neither they, nor anybody else in our group that weekend had any real idea.

Then, a number of years later, in April 2003, I was at last able to pinpoint the general area in Death Valley where those late Pleistocene Lake Rogers sediments could be found--an extensive body of water that had actually been a geologic contemporary of famous Pleistocene Lake Manly, the great freshwater lake that had stretched 90 miles long by 6 to 11 miles wide, covering most of the floor of what is now modern-day Death Valley to a maximum depth of over 600 feet during its highest stand roughly 185 to 160 thousand years ago.

A long, leisurely hike amidst those Pleistocene Lake Rogers sediments disclosed many fossil bone fragments, plus one readily identifiable horse astragalus (colloquially called the ankle bone) that had weathered out on the surface. This fossil astragalus from a 15,000-year-old horse was one of the most personally meaningful and exhilarating fossil finds I have ever made; I had actually been able to find an identifiable vertebrate fossil from the very locality that had first powered my interest in fossils in Death Valley. The fossil, of course, remains just where I found it, way out there in a rugged badlands region in Death Valley National Park, a foot bone from a horse that had roamed the shores of a pristine lake roughly 15 thousand years ago.