Page:The Journal of geology (IA journalofgeology21894univers).pdf/428

has become so classic through the contributions of the elder Hitchcock. This horizon is one of extreme variability and no one name can be given it that will have anything like a general descriptive application. Further south Mr. Wolff has described it as a conglomerate-schist,^[1] but there the percentage of feldspar, both secondary and original is large and the rock has a marked schistosity. Another phase from the Mendon section is a well-developed conglomerate in which the pebbles vary in size from a pea up to small boulders. The larger ones are nearly all of vitreous quartz, many of a fine blue color. At East Clarendon nearly all detrital material is obliterated by the shearing action that has developed the perfect lamination observed there. Exposed south of Mendon village this horizon is a vitreous massive quartzite, probably 500 feet thick, devoid of all evidence of stratification. Three miles south of there, the quartzite has disappeared and a well-laminated muscovitic gneiss, similar to that occuring at East Clarendon and Bald Mountain east of Rutland, takes its place. One mile north of Chittenden a remarkable phase occurs; the rock as a whole is still a vitreous quartzite, but it is made up almost entirely of angular and rounded boulder-like areas of the same material. The boulders seem to represent in part an original conglomerate. If boulders of a composite nature were deposited with those of quartz, the silicates have been converted into what little ground-mass the rock now possesses. After the rock was cemented into a vitreous quartzite, brecciation took place, and today we see a mixture of genuine boulders, some having a diameter of several feet, and pseudo-boulders of larger dimensions, some angular and others having rounded outlines. imitating genuine clastics. The former are identified by their occasional occurrence in a matrix or cement that has protected them from distortion or granulation. East of Chittenden flats an even greater development of quartzite occurs where its thick-