248 ANNALS NEW YORK ACADEMY OF SCIENCES 



and Trenton ages from this belt, showing that all these terranes are pres- 

 ent. He called attention to the fact that as one goes eastward in this belt 

 the rock displays greater crystallinity. Much evidence of crushing be- 

 comes manifest and bunches and veinlets of calcite, nests of quartz and 

 stringers are abundant, indicating hydrothermal activity. These changes 

 have obliterated all traces of organic remains. 



The limestone of the Clove Valley is essentially a fine-grained gray to 

 white crystalline variety. The individual calcite grains range in size 

 from' one-tenth to two-tenths millimeter in diameter. Small bunches 

 and stringers of secondary quartz are frequently present. On the east and 

 west, the limestone is overlain by phyllites belonging to the Hudson River 

 series. 



The limestone appears again six miles to the east in the Dover-Pawling 

 Valley. Here it is considerably more metamorphosed, as is shown by its 

 coarse crystalline texture. In places, as in the vicinity of South Dover 

 and Wingdale, it is quite pure and makes an excellent marble. It has 

 been quite extensively quarried at these places. At other localities, 

 phlogopite and tremolite occur quite abundantly distributed through it. 

 The development of tremolite crystals in the limestone is especially well 

 shown in some of the cuts along the New England Railroad from Towners 

 to West Patterson. They frequently become an inch long and over a 

 quarter of an inch in diameter and make up a goodly percentage of the 

 rock. 



I HUDSON RIVER SLATES, PHYLLITES AND SCHISTS 



Resting on the Wappinger Limestone is a thick series of slates belong- 

 ing to the Hudson River group. The slates range in age from Trenton 

 into Cincinnatian.^^ These strata are strongly folded and crumpled, and 

 for this reason their exact thickness is unknowTi, but probably exceeds 

 several thousand feet. 



Just east of the Hudson River, a slaty shale derived from an impure 

 argillaceous mud is the predominating type. Interbedded with this shale 

 are occasional sandstone beds. Following these slates eastward from the 

 Hudson River, an increase in the amount of metamorphism which they 

 have undergone becomes very noticeable. In the vicinity of Arthursburg, 

 they have been altered to slaty phyllites and graywackes. 



The formation at Arthursburg is typically a slaty phyllite broken up 

 into a large number of comparatively thin lamellae by numerous parallel 

 cleavage planes. It has a dark bluish gray color and is fine grained. In 

 thin section under the microscope, it is seen to be made up chiefly of a 



58 C. E. Gordon : N. Y. State Mus. Bull. 148, p. 96. 1911. 



