2006 Philadelphia Annual Meeting (22–25 October 2006)

Paper No. 10
Presentation Time: 10:50 AM


FLEEGER, Gary M., Pennsylvania Geol Survey, 3240 Schoolhouse Road, Middletown, PA 17057-3534 and INNERS, Jon D., 1915 Columbia Avenue, Camp Hill, PA 17011, gfleeger@state.pa.us

An intriguing omission in the writings of Henry David Thoreau is any mention of continental glaciation in his descriptions of the New England landscape. He observed and measured glacial striations on Mt. Monadnock and described roches moutonnees on Monadnock and Mt. Katahdin—but failed to elaborate on their origins. The glacially transported boulders on the summit of Monadnock, he ascribed to transportation by “the Titans.” He noted many erratic boulders in the woods and fields around Concord, but offhandedly dismissed the origin of the rocks at the “Boulder Field” in the Estabrook Woods as having “tumbled and split off from an iceberg.” On his four trips to Cape Cod, he made no effort to see Doane's Rock in Eastham, by far the largest glacial erratic on the forearm of the Cape.

Thoreau's most insightful observations on glacial landforms involved Walden Pond, a large kettle pond in the southeastern corner of Concord. He accurately surveyed and sounded the pond in 1846, and noted the annual rise and fall of its water level. He correctly deduced that Walden is a flow-through pond, having underground connections to topographically higher ponds to the northeast and to the lower Sudbury River to the southwest.

Thoreau's early mentors on the “diluvial” geology of New England were C. T. Jackson and Edward Hitchcock. Jackson's rather uncritical acceptance of the Noachian flood origin of the drift is readily explained by the fact that his work in Maine during the 1830's predated the wide dissemination of the ideas of Bernhardi, Charpentier, and Louis Agassiz on continental glaciation in Europe. Hitchcock's early work in Massachusetts was contemporaneous with that of Jackson, but by 1841 he was a strong supporter of Agassiz. Over the next 20 years, however, he gradually drifted back toward “diluvialism.” In 1862 Hitchcock stated that the flood/iceberg and glacial theories on the origin of the drift “were not irreconcilable.” Agassiz came to Boston in 1846. Thoreau collected zoological specimens for the great naturalist's Harvard museum in 1847, and read a copy of “Agassiz sur les Glaciers” in 1854. But Thoreau's Journal and late essays maintain a cryptic silence on Agassiz's views on New England glaciation. Most likely, this omission reflected Thoreau's distrust of science as expressed in his polite refusal of membership in the AAAS in late 1853.