. Bulletin of the Geological Society of America. Geology. DETAILED GEOLOGY OF SILVER CITY RIDGE 423 posed of grains of pure quartz sand cemented with quartz with a variahle proportion of chlorite in those portions which are of oreenish sliados. Beds of the latter shades are generally finely laminated and originally probably contained some argillaceous and ferruginous material. The lamination is original, being due to conditions of sedimentation and not to parallel development of minerals induced by tlie pressnre. The upper layer of the latan limestone at the point A is of the noi-mal character
. Bulletin of the Geological Society of America. Geology. DETAILED GEOLOGY OF SILVER CITY RIDGE 423 posed of grains of pure quartz sand cemented with quartz with a variahle proportion of chlorite in those portions which are of oreenish sliados. Beds of the latter shades are generally finely laminated and originally probably contained some argillaceous and ferruginous material. The lamination is original, being due to conditions of sedimentation and not to parallel development of minerals induced by tlie pressnre. The upper layer of the latan limestone at the point A is of the noi-mal character and continues so to the point B. Just east of P> tlie cracks in the limestone are filled with hard black chert, which within a distance of. FicruK -The Siliei- Citij Anticline Elevations are based on an assumed elevation of 1,000 feet. The area within the heavy line is underlain by the altered rocks a hundred or so feet to the east comj)letely takes the place of the lime- stone, tlie cliange being g]-adua]. 'I'lie strata are well exposed, so that no mistake of identity is ])ossil)le. The change is also accompanied l)y a thickening of the l)ed, an inci-easing ])ercentage of impurity therein, and the assumption of a greenish shade. Fossils are visible in the re]daced rock. A thin-section made from the chert tilling the cracks in the lime- stone shows nothing othei* than would be expected in such a rock. A section from the equiAalent of the limestone east of B shows the develoj)- ment of a considerable amount of chloi'itc. At (^ there is no ti-ace of the limestone, but what appears to l)e its stratigraphic position is held l)y a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Geological Society of America. [New York : The Society]
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
