. Bulletin - New York State Museum. Science. 1052 NEW YORK STATE MUSEUM Ten feet lower, or from 12 to 13 feet below the base of the upper Stromatopora bed, is a third one, averaging 2 feet in thickness. This has the aspect of a curly or concretionary rock, is of a darker color than the inclosing Manlius, and often highly crystalline. The structure of the Stroniatopora appears on weathered faces only. The bed occasionally thins and then swells out again but does not exceed 2 feet in thickness. Its lower and upper contact surfaces are very irregular, and a certain amount of erosion (probably con
. Bulletin - New York State Museum. Science. 1052 NEW YORK STATE MUSEUM Ten feet lower, or from 12 to 13 feet below the base of the upper Stromatopora bed, is a third one, averaging 2 feet in thickness. This has the aspect of a curly or concretionary rock, is of a darker color than the inclosing Manlius, and often highly crystalline. The structure of the Stroniatopora appears on weathered faces only. The bed occasionally thins and then swells out again but does not exceed 2 feet in thickness. Its lower and upper contact surfaces are very irregular, and a certain amount of erosion (probably contemporaneous) appears to have occurred before the deposition of this bed. This is indicated by the wedging out of a 2 foot bed of Manlius lime- stone just below the bed, as shown in the annexed figure. Both the lower and mid- dle Stromatopora beds and the intervening rock are fis- sured and veined with cal- cite, which is often coarse- ly Crystalline. A Certain . n Diagram of part of Stromatoppra bed ^ d m city quarry, Hudson, snowing the thinning out amount of slickensiding has of the Umestone layer beneath * also occurred, showing slight readjustment of the strata. In the southern end of the quarry over 40 feet of the Manlius were at one time exposed without reaching the " Hudson ; Contacts between Manlius and Coeymans. The contact between the Manlius and Coeymans, or the Siluro-Devonic cod tact, is shown in numerous exposures on the mountain. From the ex- posure at the head of the aqueduct in Greenport it can be traced westward for a short distance, when it disappears under drift. Scattered ledges of both upper and lower rock allow its approxi- mate determination to the city quarry, where, as noted, it is again well shown. Beyond that it is traceable southwestward and southward in the cliffs and on the slope of the hillside, with some intermittances, though seldom with a well exposed contact, to the Jonesburg road. On the south edge of this, after cross
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1887
