No. 104.] 173 



III. 

 Highlands of the Hudson. 



The above designation, or as it is sometimes used, the Higlilands, is 

 given to the mountain chain, which extends from New Jersey, through 

 Orange and Kocklaud counties and, on the east of the Hudson 

 river, through Putnam and Dutchess counties, nearly to Connecticut. 

 The Hudson river crosses it between Peekskill and Cornwall. Its 

 average elevation above the ocean is about 1,0U0 feet, and it is so much 

 more elevated than the valleys on the north and south that it is some- 

 times designated as a table land. There are, however, some rather 

 deep valleys traversing it on nearly due north and south lines, and 

 many lesser depressions whose general course is from north-east to 

 south-west approximately, and which alternate with rocky ridges, 

 having the same trend. The height of these several ridges is remark- 

 ably uniform, pointing to an original plane or nearly level surface, 

 which, through the denudation of the softer and more exposed strata, 

 has resulted in the corrugated features now observed. The general 

 level of these crests is at once apparent on climbing to them. The 

 valleys are not alike uniform in depth, as for example that of the 

 Hudson river crosses it below tidal level, whereas the Ramapo valley 

 is several hundred feet higher, and that of Peekskill Hollow still 

 higher. 



The Highlands east of the Hudson may be said to extend north-east 

 from the Hudson river, from Peekskill Hollow and Cornwall to Car- 

 diner's Hollow, near Poughquag, and to Whaley pond, west of Paw- 

 ling, in Dutchess county, and to the Pawling-Patterson valley, in Put- 

 nam county. The southern limit is Peekskill Hollow to Oregon ; then 

 an irregular and not well-defined line near Shrub Oak, Jefferson Val- 

 ley, Somers Hollow, and Croton falls to Brewsters. These lines do 

 not include all of the ridges on the north and east, since the Fishkill 

 mountain range continues north through Dover, Amenia and north- 

 east to its termination near Copake in Columbia county. Eastward 

 the ridges follow one another without any well-marked line of division 

 through the towns of Southeast and Patterson, in Putnam county, into 

 Fairfield, Connecticut. On the south-east the hilly country of the 

 northern part of Westchester county border the Highlands. 



The extreme north-east limit, geologically considered, of the High- 

 lands belt is in the town of Beekman and at Gardiner's Hollow.* The 

 gneissic rocks at this place arc found lying unconformably against the 

 micaceous and quartzose schists of the Dover and West Pawling 

 range. This most interesting locality is less than a quarter of a mile 

 north of what is locally known as the " Dug road." The full descrip- 

 tion of the north-west boundary of the Highlands Archrean rocks may 

 be given as follows : Beginning at the north-easternmost point, the 



* The probable termination of the Highlands belt of Archtean rocks, near this locality, 

 was first suggested to the author of this paper, by a trip through this part of the State ia 

 1880, while visiting the iron mines for the U . S. Census Otfice. At the close of the season 

 the work of Dr. Percival was examined, and his description of the locality was at once 

 verified, ^ee Percival' s Geolo'ji/ of Co7t,necticut, p. 123. 



Prof. James D. Dana has represented the Archaean Highlands, as terminating near 

 Poughquag, on a map which accompanies an article on the "Geological relations of the 

 Limestone Belts of Westchester countv, New York." Am. Jour, of Science {Z), XX; facing 

 p. 452. 



