Geology of the Broadalbin Quadrangle, Fulton-Saratoga Counties, New York (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 Excerpt: ...this erosion period so that with the inauguration of Black River-Trenton time those limestones were deposited directly upon the Little Falls dolomite. BLACK RIVER-TRENTON LIMESTONES As a result of recent changes in the nomenclature of the Lower Paleozoic formations of northern New York, the term "Black River" is no longer applied to a single limestone formation but rather to a group of three formations. The Black River group, as now recognized by the Survey, comprises the Lowville, Watertown, and Amsterdam limestones and of these only the Lowville and Amsterdam limestones appear to be present in the lower Mohawk valley. The missing Watertown corresponds to the well known Black River limestone of the Black River valley. Because of the thinness and small areal extent of the Black River-Trenton limestones they are shown together on the accompanying geologic map. LowVille limestone. The Lowville (former "Birdseye") formation is commonly present within the map limits, but it is never more than a few feet thick. The following description of this limestone by Darton1 for the Mohawk valley well applies to the Broadalbin district: "The Birdseye is in greater part an impalpably fine-grained, light dove-colored limestone more or less filled with dark-colored, vertical, columnar fucoidal stems. lt weathers to white or a light ash gray tint, which is an especially characteristic feature. Owing to its very fine grain and compact structure its fracture is smooth or conchoidal and the texture of the rock is rather brittle. The ends of the dark fucoidal stems which are spotted over the surface of the bedding planes resemble birds' eyes, and from this feature the old name of the formation is was derived. It is in moderately heavy, regular beds and ha...