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land, separated by the Piedmont region. The eastern of these 

 (Manhattan Prong) forms Manhattan Island; the western 

 (Reading Prong) runs in a narrow belt across New Jersey 

 (Sussex, Passaic, Morris, Warren, and Hunterdon Cos.) to 

 Reading, Pa. The New Jersey Highlands and Ramapo Moun- 

 tains lie in this prong. It is separated from the Triassic Pied- 

 mont to the east by a gigantic fault scarp. This fault was doubt- 

 less begun during the Appalachian Mountain revolution and 

 formed the western edge of a large arid or semi-arid valley 

 which, through erosion from the mountains to the east and 

 west, filled with sand during the Triassic. The flows of lava 

 which now form the Watchung Mountains doubtless came up 

 along this fault and spread eastward over the valley of sands. 

 There were a number of lava flows, all in late Triassic time. 

 Both the First and Second Watchungs are made up of several 

 separate lava flows, those of the First being the oldest. In some 

 cases (like Eagle Rock and Garret Rock) the lava seemis to have 

 come up through vents. Several large volcanoes were located 

 along the fault line during this time. The climate was generally 

 cool. Fossils of a few small fresh-water fish and some fragments 

 of land plants have been found. The fern fragments seem to 

 indicate that they were washed in by floods from the surround- 

 ing mountains. Cycads were common and there were a few 

 lingering pteridosperms. Some of the so-called algae described 

 from the region are not plants at all, but are merely ripple- 

 marks. They are commonly found in the old shallow lake-beds 

 along with abundant mud-cracks, attesting to the arid or semi- 

 arid climate. It was the early reptilian age, marked by the rise 

 of dinosaurs. Footprints of small dinosaurs are commonly found 

 through the region, mostly of the 3-toed, bird-like, carnivorous 

 species, which fed upon one another. The mountains surround- 

 ing this vast sandy valley may have been sparsely covered with 

 vegetation. The preceding geologic period had been very cold 

 and characterized by many vast glaciers which certainly ex- 

 terminated all the early plants of the region. The vegetation, 

 however, gradually came back during the Triassic and Jurassic, 

 so that in Cretaceous time there was an abundant flora over 

 the area, including grasses and primitive dicotyledons. In the 

 Triassic, conditions here were similar to those in valleys in the 

 West today. Heavy rains during the winter washed much sand 



