Seneca Quarry

Seneca Quarry is a historic site located at Seneca, Montgomery County, Maryland. It is located along the Chesapeake and Ohio Canal on the north bank of the Potomac River, just west of Seneca Creek. The quarry was the source of stone for two Potomac River canals: the Patowmack Canal (opened in 1802, and officially known as the Great Falls Skirting Canal) on the Virginia side of Great Falls; and the C&O Canal, having supplied red sandstone for the latter for locks 9, 11, 15 - 27, and 30, the accompanying lock houses, and Aqueduct No. 1, better known as Seneca Aqueduct, constructed from 1828 to 1833. Seneca red sandstone, also known as redstone, formed during the Late Triassic age, 230 to 210 million years ago. The current geological name is Poolesville Member of Manassas Sandstone. Iron oxide gives the sandstone its rust color. It was prized for its ease of cutting, durability and bright color. The stone quarried here for the Smithsonian Castle was originally described as "lilac grey" in color when quarried, but turned rusty red as it weathered. Numerous quarries operated on the one-mile stretch of the Potomac River west of Seneca Creek. The C&O Canal provided a way for the heavy sandstone to reach the Washington, D.C. market, and the quarry's success is attributed to the canal. The Peter family of Georgetown, which built Tudor Place, owned the quarry from 1781 until 1866. John

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