Most red abalone middens cover areas less than 75 meters in diameter, and their deposits are only about 30 centimeters thick.  They are discontinuously distributed along the coast from the western extreme of the island to Punta Arena, located on the south coast.  Two of the red abalone middens, however, are much larger than the rest, these being located at the westernmost and easternmost extreme of their distribution.  Red abalone midden deposits at these two sites are over 150 meters in diameter, and their deposits are over a meter thick.

To date, 13 red abalone sites are associated with radiocarbon dates, and several others are recorded but have not yet been radiocarbon-dated.  Red abalone middens next to the coast typically are buried under Aeolian or alluvial deposits, and their discovery has depended on exposures of the midden deposits on seacliff or gully walls.  Three of the dated sites are set back from the coast up to 1.8 kilometers, and two more not yet dated are 1.9 and 2.6 km from the coast.

Radiocarbon dates I obtained for red abalone middens led me to realize that nearly all fell within a relatively narrow bracket of time centering around 5,500 years ago.  Since my initial work in the 1980s, my field class students and I have located several more red abalone middens, and radiocarbon dates obtained for some of these indicate a similar age.  As more radiocarbon dates were obtained, it became clear that dates for red abalone middens fell within a 1,000-year bracket of time between 6,300 and 5,300 years ago.

peter excavating

A red abalone midden buried under nearly a meter of alluvium


Red abalone midden within dune deposits beneath a midden dating after 3,500 years ago



Red abalone midden exposed along seacliff