BLASTING ROCK, BUILDING LOCKS, AND HAULING COAL: GEOLOGICAL INFLUENCES ON THE CONSTRUCTION AND OPERATION OF THE DELAWARE AND HUDSON (D&H) CANAL, NEW YORK AND PENNSYLVANIA

The D&H Canal—one of the great American engineering projects of the first half of the 19th century—was designed to carry Pennsylvania anthracite to New York markets. Constructed in only three years (1825-1828), it ran from Honesdale, PA, to Kingston, NY, a distance of 108 miles and followed the valleys of the Lackawaxen, Delaware, and Neversink Rivers and Rondout Creek to the Hudson River. Geological influences on the canal included: 1) natural obstacles to be overcome by engineering; 2) construction stone and materials used for the locks, aqueducts, and canal walls; and 3) natural resources transported between canal ports.

The most significant geological obstacles encountered by the builders of the canal were the Narrows of the Lackawaxen, the Delaware River crossing, the Hawks Nest cliffs, and High Falls on Rondout Creek. Extensive blasting and construction of high rip-rapped embankments overcame the first and third; the building of a great suspension aqueduct in 1847-48 (designed by John Roebling) effectively improved the second; and construction of a flight of six locks in half a mile conquered the fourth.

Stone used to construct canal locks (108), aqueducts (22), and towpath/berm-bank walls varied along the route directly with the underlying geology. Between Honesdale and Port Jervis, NY, Catskill “bluestone” was used almost exclusively. From Port Jervis to High Falls, Shawangunk conglomerate was the dominant construction stone, though Helderberg limestone was preferred for cut-curves in the gate pockets of locks. From Rosendale to Kingston, nearly all existing stonework is Helderberg limestone. Hydraulic cement from the Rosendale area, discovered as early as 1818, was utilized for construction along the entire length of the canal.

The transport of anthracite to tidewater was the raison d’etre of the canal. (Because of the high mountain rim surrounding the Northern Anthracite field, coal had to be carried to the docks at Honesdale by a gravity railroad.) Other natural resources that were important components of canal transportation included Catskill “bluestone,” Shawangunk dimension stone, Rosendale cement, and various iron ores. The peak annual quantity of coal hauled to tidewater was about 1,300,000 tons in 1864, after which the canal rapidly lost out to competing railroads; it closed in 1898.