NEW YORK. 



69 



as 2600 feet, and in many places the walls are very precipitous. The rock is gneiss, of a kind 

 that is not easily disintegrated or eroded, nor is there any evidence of any convulsive movement. 

 It is clearly a case of erosion, but not by the present river, which has no fall, for tide water extends 

 100 miles up the river beyond the Highlands. This therefore was probably a work mainly performed 

 iu some past period when the continent was at a higher level. Most likely it is a valley of great 

 antiquity. Also see notes 17 and 118. 



7. Opposite Fishkill is Newburg, which is in the great valley of Lower Silurian or Cambrian 

 limestone and slate. North of that, on the west side of the river, the formations occur in their 

 usual order, their outcrops running northeast and southwest. On the N. Y. C. & H. R. E. R., on 

 the east side, the same valley crosses, and the slates from Pishkill to Rhinebeck are about the 

 same place in the series; but being destitute of fossils and very much faulted, tilted and disturbed, 

 their precise geology is uncertain. See the exposures in the cuts at Poughkeepsie. The high 

 ground to the east is commonly called the Quebec group. See notes 116 and 117. 



8. Rhinebeck. A series of great dislocations with upthrows on the east side traverse eastern 

 North America from Canada to Alabama. One of these great faults has been traced from near the 

 mouth of the St. Lawrence River, keeping mostly under the water up to Quebec just north of the 

 fortress, thence by a gently curving line to Lake Champlain or through Western Vermont across 

 Washington County, N.Y., to near Albany. It crosses the river near Rhinebeck 15 miles north of 

 Poughkeepsie and continues on southward into New Jersey and runs into another series of faults 

 probably of a later date, which extend as far as Alabama. It brings up the rocks of the so called 3 

 b. Quebec group on the east side of the fracture to the level of the 4 c. Hudson River and 4 a. 

 Trenton 1. s. 



9. Catskill Mountains. For many miles on this railroad are beautiful views of the Catskill 

 Mountains, 3,000 feet high, (12. Catskill,) several miles distant on the opposite or west side of the 

 river, and which furnish the name for the Catskill formation. The wide valley between them and 

 the river is composed of 11 b. Chemung, 10. Hamilton, 7. Lower Helderberg and 4 c. Hudson River. 

 The geology on the east or railroad side is entirely different. 



10. Albany. The clay beds at Albany are more than 100 feet thick, and between that city and 

 Schenectady they are underlaid by a bed of sand that is in some places more than 50 feet thick. 

 There is an old glacial clay and boulder drift below the gravel at Albany, but Professor Hall says it 

 is not the estuary stratified clay. At the south end of the city of Troy the gravel and sand beds are 

 subject to dangerous land slides. 



11. The distant mountain to the southwest is the Helderberg range. See notes 24 and 41. 



12. Amsterdam. Precipice of 4 a. Trenton limestone back of the town, and quarries at the 

 track. For 40 miles to Little Falls the railroad runs on Trenton limestone 3 a. Calciferous, 4 b. 

 Utica and 4 c. Hudson River irregularly alternating. 



13. Branch railroad north to Johnstown and Gloversville, in a valley of Utica slate. 



14. Between Fonda and Palatine Bridge are fine bluffs of 3 a. Calciferous. The talus of fragments 

 of rock at the foot of the precipice whiten out in weathering like the stones about an old lime-kiln. 

 It is from the cavities of the Calciferous that the beautiful quartz crystals are produced, of which 

 great quantities have been found. A similar bluff on south side of river. No Potsdam here. 



15. The railroad skirts along the base of a ridge of Trenton limestone here and at Fort Plain. 



16. At Fort Plain village the transition from the Birdseye to the Trenton limestone is to be seen, 

 the first layers of the latter being of a drab color. 



17. At Little Falls for one mile is a rare opportunity of seeing the 1 a. Laurentian formation, 



