412 THE JOURNAL OF GEOLOGY. 



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,^ but there the percentage of feld- 

 spar, 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 mas- 

 sive quartzite, probably 500 feet thick, devoid of all evidence of 

 stratification. Three miles south of there, the quartzite has dis- 

 appeared 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 elastics. 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- 



* Metamorphism of Clastic Feldspar in Congloimerate Schist, Bull. Museum Comp. 

 Zool. Whole series Vol. XVI., No. 10, Plate II, shows two excellent microphoto- 

 graphs of this phase of the conglomerate where the clastic material is nearly 

 obliterated. 



