GEOLOGY OF THE REMSEN QUADRANGLE 



29 



cal. Although these joints show great variation in direction and 

 degree of development, nevertheless over most of the Paleozoic area 

 two sets running approximately east-west and north-south appear 

 to predominate. These are particularly well seen in the vicinity 

 of Trenton Falls and Remsen. The vertical walls of the gorge at 

 Trenton Falls are principally due to the breaking away of large 

 limestone masses along the north-south joint planes. The east- 

 west joints may here be seen extending across the stream at many 

 places, but especially at the falls themselves. The falls are all due 

 to the existence of the joints since when a large mass of limestone 

 is removed a vertical wall is left over which the water falls. Thus 

 the falls retreat and reform by the removal of joint blocks as, for 

 example, in the case of Sherman fall. Here at high water the 

 water falls over one joint plane on the eastern side and over an- 

 other a number of feet back on the west side. When the water 

 is low it all passes over the rear joint on- the west [see pi. 2]. It 

 is very evident that, in the course of time, the whole block of lime- 

 stone left between the two joints will be removed. 



In the bed of Cincinnati (Town Line) creek, from 1 to 1 J miles 

 below Remsen an interesting drainage feature is due to the joint 

 planes in the coarse crystalline (upper Trenton) limestones. Sev- 

 eral hundred yards above the bridge, at time of low water, the 

 stream disappears entirely through the joints and after a subter- 

 ranean course, mostly along the joints, it reappears near the bridge. 



Foliated structure 



A foliated or gneissic structure is highly characteristic of all the 

 Precambric rocks. It is exhibited best of all in the ancient Gren- 

 ville sediments, next best in the rocks of the Syenite- Grenville com- 

 plex, and least in the pure syenite. The excessive foliation of the 

 Grenville is accentuated by the alternating light and dark bands 

 above described. The foliation of the syenite though distinct is 

 brought out only by the dark, narrow, irregular, wavy streaks 

 passing through the otherwise homogeneous rock mass. 



As a result of many readings it may be stated that the Pre- 

 cambric foliation planes all show a strike varying between n. 6o° 

 e. and n. 8o° e. This result agrees closely with that obtained by 

 Cushing for the Little Falls quadrangle and for the Long Lake 

 quadrangle of the mid-Adirondacks. The dip of the foliation 

 planes is sometimes north and sometimes south but nearly always 

 at very high angles. Often the Grenville and the Syenite- 

 Grenville complex rocks are locally highly plicated or crumpled 



