The northern Channel Islands — San Miguel, Santa Rosa, Santa Cruz, and Anacapa — were his particular area of focus.

Santa Rosa Island was, and remains, the second largest of the Channel Islands, a roughly 84-square-mile piece of terrain some 50 miles west of Santa Barbara.

It is rugged country — canyons cut by streams through deposits of marine terrace and alluvium, ridges covered in shrubby vegetation, coastline alternating between sea cliffs and small beaches.

The island belongs to the Channel Islands National Park, established in 1980, but in Orr’s time it was a working cattle ranch.

He had been coming to Santa Rosa Island for years before 1959, building a picture of its geological and archaeological history.