The flora of the Watchung Mountains 



Harold N. Moldenke 



Part I — Geology of the Region* 



Fi\e phytogeographic provinces are represented in the Local 

 Flora area. The area is therefore the most compHcated, physio- 

 graphically and phytogeographically, of any similar-sized area 

 in all of North America. This fact must be borne in mind when 

 one studies the flora of any part of the local area, such as that 

 of the Watchung Mountains. 



The Watchung Ridges (as they are termed by geologists) 

 or Watchung Mountains (as they are known locally) are three 

 in number.^ Of these the longest is the First Watchung, which 

 is also the farthest east. It is approximately 50 miles in length, 

 through eastern Passaic Co. and western Essex and Union Cos., 

 forming a bow-like curve from western Bergen Co. on the north, 

 terminating in northern Somerset Co. It passes through Pater- 

 son and just west of Orange and Plainfield, and at Bound Brook 

 turns sharply westward to Pluckamin. The Second Watchung 

 parallels the First, only a mile or so westward, and separated 

 by a belt of red sandy shales forming the shallow W^ashington 

 Valley. It runs through Little Falls, Caldwell, and Summit, and 

 in northern Somerset Co. swings sharply to the west and then 

 north, terminating at Bernardsville. The so-called Third 

 Watchung is really a series of 4 disconnected ridges closely 

 parallel tD the First and Second, but lower and separated by a 

 narrow red sandstone belt. Still farther westward, wholly in 

 Morris Co., is a fourth ridge, very small and crescent-shaped. 



The Watchung Mountains are in general about 500 or 600 

 feet high — the highest point being High Mt. (876 ft. above 

 sea-level) just north of Paterson in the Second Watchung. All 

 four series of ridges lie within the so-called Piedmont physio- 

 graphic and phytogeographic province and are made up of vol- 

 canic rock (basalt), wath, in a very few isolated spots, narrow 

 intervening bands of red sandy shale of the same sort as makes 

 up the valleys between them. They are of Triassic age. They 



* Part 2 of this paper, on the plants of the region, will be printed in the 

 next number of Torreya. 



' The author is deeply grateful to Dr. B. T. Butler, head of the Depart- 

 ment of Geology at the College of the City of New York, for the copious help 

 given him in the preparation of the geological portion of this paper. 



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