Stone-by-Stone Metrics Shed New Light on a Unique Stone Alignment at the Point Reyes National Seashore, Marin County, Alta California

Abstract

The origin of a 260-meter alignment of granite boulders at the Point Reyes National Seashore is not known. An oral tradition says that it was built during prehistoric times by the Coast Miwok, but historical and circumstantial evidence associates it with nearby ranches. Detailed measurements on 322 boulders in the alignment demonstrate that the builders placed large oblong stones parallel to the main axis of the line and small oblong stones perpendicular; similar techniques were used by the builders of New England's historic stone walls. A 10-meter gap is present in the line and there are not enough extra stones near the gap to fill it. This suggests that the gap was planned from the beginning by the builders of the line. An 1862 map shows features at the gap that could represent paddocks and gates. North of the gap, the line changes direction by 10 degrees to intercept the head of a steep ravine. The alignment resembles a nearby American period unfinished section of stone wall. The evidence indicates that the line was built by nineteenth-century ranchers as a property boundary or as a stone wall that was never finished.