Beneath Highland Light a Singular Layer of Clay with a Mysterious Name

Oct 10, 2017

Cape Cod National Seashore, Massachusetts. The "clay pounds" at Highland Light in front of the wireless station, looking south 5 degrees east. Jameco Gravels at the base, Gardiners Clay in the middle, and Jacobs Sands at the top of the section. June 3, 1916.

The Clay Pounds are one of the few geological features on Cape Cod’s Outer Beach that have endured long enough to have acquired a name. Located just north of Highland Light in north Truro, the Clay Pounds comprise a 40-foot thick band of nearly pure blue clay. Nowhere else on the Cape does anything approach these massive sedimentary deposits.

While the name Clay Pounds is universally used, its origin, at least the latter part of it—“Pounds”—remains obscure. Thoreau, during his visit here in 1849, meditated on two possible explanations:

"We read [he writes] that the Clay Pounds were so called ‘because vessels have had the misfortune to be pounded against it in gales of wind,’ which we regard as a doubtful derivation. There are small ponds here, upheld by the clay, which were formerly called the Clay Pits. Perhaps this, or Clay Ponds, is the origin of the name."

Others have suggested the name comes from the loud sound made by waves pounding against the clay cliffs. 

According to the geologist Barbara Chamberlain, these thick, rugged clay bluffs were laid down as glacial lake deposits during a “quiet time” following a warming interglacial period that existed about 50,000 years ago, and then were “humped up” when the next advance of the glaciers moved through.

These clay deposits extend to include the land beneath Highland Light, and in fact were likely responsible for the lighthouse being built there. In 1794 the Reverend Levi Whitman of Wellfleet sent a letter to the Rev. James Freeman of Boston writing about the Clay Pounds in a manner that combined Christian and capitalistic concerns:

"That mountain of clay in Truro [he writes] seems to have been erected in the midst of sand hills by the God of Nature for the foundation of a lighthouse which, if it could be obtained, in time no doubt would save the lives of thousands, and millions of dollars in property. Why then should not that dark chasm between Cape Ann and Nantucket be illuminated?"

Four years later, in 1798, the first Highland Light was built on a ten-acre parcel of land bought by the U.S. Government from Isaac Small. The present light was constructed in 1857.

The construction of Highland Light may have saved many a vessel, but an alarming number of wrecks continued, providing a steady business for the Cape’s salvagers, or “wreckers’ as they were called. Most wreckers were amateurs and opportunists, but the Hon. E. Hayes Small of North Truro, born in 1880, was, if not professional in name, certainly one in practice. As a young teenager he got his first taste of wrecking, and in his early 20s got himself appointed as an assistant keeper to Highland Light. As Cape historian Henry Kittredge commented, it was “a position which, though it brought him no riches from the Government, gave him a fine chance to keep a weather eye open for riches from the sea.”

Over the years Small and crew of men and as many as eight horses, hauled tons of lumber and other cargo off ships that wrecked beneath the cliffs of the Clay Pounds.

Yet despite their dramatic appearance and the significant part they played in the Cape’s maritime history, relatively few people visit the Clay Pounds these days, and next week I’ll tell you why.