Though he's written scientific studies like “The Chimpanzees of Kibale Forest” (Columbia University Press, 1984) and treatises on psychology like “The Dark Side of Man: Tracing the Origins of Male Violence” (Perseus Books, 2000), his work took a sharp turn in 2001.

When his proposal for “Over the Edge: Death in Grand Canyon” was rejected by the publishing arm of the Grand Canyon Association, he wrote and self-published the book with Thomas M. Myers, a canyon physician.

Part of the gruesome appeal of “Death in Grand Canyon” are the tales of hapless victims who backed up over the canyon rim while posing for photographs (seven)—or who slipped while relieving themselves into the chasm (at least five).

But both books are also filled with serious historical information. In “Death in Yosemite,” sections are devoted to the 19th-century persecution of the Sierra Miwok Indians and the construction, over the objections of environmentalists, of the Hetch Hetchy Reservoir on the Tuolumne River to satisfy the water needs of San Francisco.

But the book's most stirring episodes are its chronicles of bad decision-making, often by experts whose wits abandoned them at key moments. In 1999, Jan Davis, a 58-year-old stunt woman, jumped from the top of El Capitan as the fourth of five demonstrators protesting the park's ban of BASE-jumping — the sport of leaping from mountains, bridges or buildings with a parachute.

Because she expected her equipment to be confiscated by park rangers, Ms. Davis borrowed a less valuable rigging with a leg-sheath pilot chute, which was different than her own back-mounted gear. Spectator videos of her fatal 3,000 foot fall showed her swatting at her back in an apparent attempt to clear her chute, but she was unable to activate the less-familiar equipment effectively.

Strung together, the tales in “Off the Wall: Death in Yosemite” offer some simple rules. Do not underestimate the spectacular, unforgiving terrain. Capturing that perfect photograph, if it involves wading anywhere near the edge of a waterfall, is suicide. Hiking alone, particularly off trail or in winter, has proven disastrous again and again.