SIXTH REPORT OF THE DIRECTOR I909 1 7 



and greenish and gneissoid rocks of this strip were found in the 

 eastern part of the town of Matteawan. Certain easily marked 

 faults have broken the areal continuity of the whole. 



The Glenham belt near Vly mountain shows a small patch of 

 the quartzite. In Matteawan a considerable knoll of the basal 

 quartzite is preserved between Anderson, Grove and Walcott 

 streets near " Rock hollow." The Precambric age of these 

 masses is thus indicated. The Glenham belt and the smaller 

 masses at the south are interpreted as inliers of the older rocks. 

 The Glenham belt is a faulted inlier. The others are probably 

 such. The rocks which make up the larger part of these inliers 

 are looked upon as altered derivatives of the gneisses. They 

 belong to the same general epoch as the quartzite, that of the 

 transgressing Cambric sea. Their present compact condition is 

 due to the same metamorphic processes that changed the basal 

 sandstone to a quartzite and the overlying limestones and slate 

 to their present condition. 



At Hortontowm, a small hamlet in the Highlands south of 

 Shenandoah, a basic eruptive made up chiefly of hornblende and 

 magnetite, with some pyroxene, is in close association with a 

 quartzite, entirely similar to the basal quartzite and of consider- 

 able extent, and with a few scattered ledges of an altered rock 

 made up of magnetite and bastite. The relations are very ob- 

 scure. The presence of a clear fault along the eastern base of 

 Shenandoah mountain seems to permit the interpretation that 

 the eruptive is of Postcambric age and that it has penetrated 

 the basal Paleozoics and altered the ferruginous dolomite with- 

 out materially afifecting the refractory quartzite. Most of the 

 altered limestone has been removed. 



Cambric. The discovery of the opercula of Hyolithellus 

 m i c a n s Billings in the bluish gray limestones overlying the 

 basal quartzite at the base of the Fishkill mountains during the 

 previous years, indicated that fossils in the quartzite would prob- 

 ably be found in the neighborhood, and a slab of compact 

 quartzite with the surfaces covered with brachiopod and trilobite 

 fragments has been found in the yard of Ward Ladue in the West 

 Fishkill Hook d's'rict south of Johnsville. This find led to a per- 

 sistent search for the quartzite in place. A few weeks later the fos- 

 sils were found about ^ mile to the south. The locality may be 

 reached by taking the east road into the mountain from the West 

 Hook, passing the house of Ward Ladue as far as Herman Adams's 



