Wappinger Valley Limestones. 141 



it is bordered on the west by a belt, from 800 to 1000 feet wide 

 in its outcrop of overlying limestone, partly at least of the 

 Olenellus group. 



After reaching the mountain, this belt follows alorig its 

 flanks to Miller's Pond, during which course, the Hudson River 

 shales on the west pinch out the limestone and rest against the 

 quartzite for about 700 feet. North of Miller's Pond, the 

 Olenellus belt begins to ascend the mountain flanks, until at a 

 point about half a mile south of the "gap," the limestone 

 entirely disappears, and the quartzite pressed upon by the Hud- 

 son River Shales stands out in bold white crags high up the 

 mountain side, — at perhaps two-thirds of its height. jSTorth of 

 this point, the Hudson River shales apparently rest directly 

 upon the gneiss. 



On the east side of Mount Stissing, the Olenellus belt does 

 not tend at any point to climb its flanks ; the tendency is rather 

 to sheer away from them. The quartzite is here mainly on the 

 west side of the belt. At a point, however, opposite to Attle- 

 bury Station, where there is a deep recess to the west in the 

 outline of the mountain, there is a synclinal of limestone and 

 calcareous shales lying west of the quartzite and filling up the 

 gap. 



A.t Mr. J. A. Thompson's house at the turn in the road north- 

 east of Attlebury Station, the quartzite disappears in the mead- 

 ows while the Olenellus limestone forms a bold escarpment 

 along the base of the mountain, west of the road, for about 

 half-a-mile farther north. Opercula of Hyohthellus micans 

 occur in this limestone opposite Mr. Thompson's house. From 

 this point the belt, much concealed by drift and alluvium, 

 passes northeastwardly by and under the village of Pine Plains 

 to the county line. There are outcrops of the quartzite in 

 Mr. Henry Pitcher's swamp, north of the village, and on top 

 of a hill belonging to Mrs. Henry Hoffman, and on the south 

 side of the road close to the county line, near Mr. J. Weaver's 

 house. There are outcrops of limestone in the plain near the 

 north extremity of Stissing Mountain, which probably belong 

 to this group, but this is uncertain. It may here be remarked 

 that the Hudson River Shales mount to the summit of that 

 part of the mountain lying north of the " gap," at least in its 

 northern portion. Also that the only other place where I have 

 found quartzite referable to the Olenellus group in this part of 

 the county is a ledge in a ravine on Wing's farm a little south- 

 west of the station at Willow Brook.* 



* My explorations around Pine Plains were much facilitated by the generous 

 assistance of Rev. A. Mattice, principal of Seymour Smith Institute. 



Am. Jour. Sci. — Third Series, Vol. XXXYLTI, No. 224. — August, 1889 

 9 



