AMERICA'S FINEST NATURAL CEMENT: THE HISTORY AND ECONOMIC GEOLOGY OF THE ROSENDALE NATURAL CEMENT REGION, ULSTER COUNTY, NEW YORK

The historical Rosendale region, in the central Hudson Valley of southeastern New York State is widely recognized as the source of the highest quality natural cement in North America. The North American natural cement industry was founded in 1819 by Canvass White in central New York, but soon shifted to Rosendale where it flourished for over 150 years. By the end of the 19th century, the superior quality of Rosendale natural cement was known worldwide and was actively used in the construction of many of America's most enduring landmarks, including the Brooklyn Bridge and the pedestal of the Statue of Liberty. Rosendale natural cement's reputation stems from the composition of the clay-rich dolostone from which it was manufactured. This dolostone was extracted using room-and-pillar techniques from strata within the Rosendale and Whiteport Members of the Upper Silurian Rondout Formation. In the central Hudson Valley, these strata are strongly deformed by thrust faults and fault-related folds within the northern Appalachian foreland fold-thrust belt. Thus, the historical mine workings created by Rosendale natural cement industry are truly something of an engineering marvel. Indeed, the unique bedrock exposures provided by the mines in the Rosendale region have long attracted the attention of geologists for research and education. The production process of natural cement transformed extracted dolostone into barrels of cement through a labor-intensive process involving calcination in kilns, cracking, and grinding. Barrels of natural cement produced in the Rosendale region were quickly shipped at competitive prices via the Delaware and Hudson Canal, which directly connected the Rosendale natural cement region to major shipping avenues.