COGNIZANCE

I enjoyed Michael Forrest’s article on cog stones (“No Stone Unturned,” So SoCal, July 28), although he never called them by name. Cog stones were manufactured 4,000 to 5,000 years ago on the Bolsa Chica Mesa in present-day Huntington Beach. While that is their only known site of manufacture, they can also be found in Chile.

Most of those in California are discovered on mesas around the historic Santa Ana River’s tributaries. Early settlers reported that the stones were strewn about local mesas, and plows have turned up quite a few.

The Bowers museum has a fine collection of cog stones, and anyone interested can visit the Bolsa Chica Conservancy’s Wetlands Interpretive Center (of which I was a former director) in Huntington Beach.

Louann Murray

Huntington Beach