[Assembly, No. 104.] 167 



I. Stissixg Mouxtaix. 



The isolated and prominent ridge, known as Stissing mountain, is in 

 the towns of Pine Plains and Stanford, Dutchess county. A depression 

 near the north end separates it into what are termed locally as "Big 

 Stissing" and " Little Stissing." The whole length is four and a half 

 miles, and the trend of the ridge is north 20*^ east. The northern 

 point of the ridge is near the Pine Plains and Mount Eoss road; the 

 southern end is about a half a mile north-east of old Attlebury, and 

 not quite one mile west-north-west of Stissing Junction. The 

 eastern side is steep, with vertical cliffs in places ; the western slope is 

 more gentle and having a more nearly uniform angle of descent. On 

 the east the mountain is bordered by the Pine Plains; on the west 

 and north is the gently-rolling slate and blue limestone country, but 

 largely drift-covered. The average breadth of the mountain varies 

 between one-half and three-quarters of a mile, that is from the border 

 of the plains to the newer rocks at the Avest foot. 



According to repeated observations with an aneroid barometer the 

 highest point of the range, near the depression and west of Stissing 

 lake or Thompson's pond, is 900 feet above the general level of Pine 

 Plains and 1,400 feet above tide. Little Stissing rises to a height of 

 550 feet above the plains. To the south-south-west the ridge lowers 

 gradually and east of Miller pond it is only 950 feet high. The most 

 southern outcrops of the gneissic rock are not more than 100 feet 

 above the plains' level, equivalent to a descent of 800 feet m three 

 miles. 



The surface of this mountain range is so rocky that its cultivation 

 in farms has scarcely been attempted, excepting a very limited area 

 on the western slope, in the gap between Big Stissing and Little Stis- 

 sing. And the limits of the cleared farm lands follow very closely 

 the foot of the mountain and the geological boundaries. 



The extent of the gneissic or crystalline rock outcrops, which make 

 up this mountain mass, outlined above in general, may be described 

 in detail, as follows: Beginning on the north about a half a mile 

 south of Keller's Corner, on the Pine plains and Mount Eoss road, 

 the eastern boundary line runs a south-south-west course, to the west 

 of Mud pond, separating the gneiss from the argillyte, nearly to the 

 depression or gap. Thence on the same general course it runs at the 

 foot of the mountain and at the border of the Plains, from an eighth 

 to a quarter of a mile west of the lakes. Here the drift formation of 

 the plains lies upon the foot of the mountain. South of the lakes a 

 greyish white quartzite makes its appearance and borders the gneiss 

 in low lying ledges nearly the whole distance to the south-west end of 

 the Stissing mountain belt or range of crystalline rocks. These out- 

 crops of quartzite were seen in close proximity to gneisses at several 

 points along this south-eastern part of the range. Their diverse dips 

 indicate unconformability.* From the southern point of the gneissic 



* Mather refers to the quartzite at the south-west side of Mount Stissing in his chapter 

 on J"Taconic System" and calls it a "granular quartz" and Potsdam sandstone. 

 Natural History of JS'eio York, Geology of Fir it District, pp. 418, 423, 436-437. 



This quartzite has been examined' by Prof. Wm. B. Dwight of Poughkeepsie, who says 

 (in a letter recently received;, that he has failed to discover any organisms in it. 



Lithologically it resembles the Fishkill and Poughquag quartzites, which have been 

 called Potsdam. 



