i6 THE RARITAN FLORA. 



THE RARITAN FORMATION. 



INTRODUCTORY. 



New Jersey has been divided into four physiographic zones. 

 The oldest of these, known as The Highlands, dates from re- 

 mote geological time, its constituent rocks consisting for the 

 most part of highly metamorphosed crystalline schists. This 

 zone occupies a broad belt across the northern central portion 

 of the State, and includes the eastern part of Sussex and Warren 

 counties, the northern part of Passaic County, most of Morris 

 County, and the northern part of Hunterdon County. It cor- 

 responds in age with the Piedmont Plateau of the states to the 

 southward, and is represented by the basal part of the section 

 in Figure i. Following the emergence of this belt C'f land in 

 early geological times, sediments were laid down along its west- 

 ern borders, and it is these Paleozoic sediments, since much 

 folded, which today make up the Appalachian ::onc, comprising 

 the Kittatinny valley and mountain of the northwestern portion 

 of the State, in Sussex and Warren counties. 



The third and next younger zone, which is known 'as the 

 Piedmont Plain, was laid down on the eastern flanks of the High- 

 land area at a much later date. Topographically, it corresponds 

 to the Piedmont Plateau region of the states to the southward, 

 but consists, in New Jersey, of much younger rocks of late 

 Triassic age, and includes roughly all or a part of Bergen, Pas- 

 saic, Essex, Union, Somerset, Middlesex, Hunterdon, and Mer- 

 cer counties. 



The fourth and youngest zone, known as the Coastal Plain., 

 includes the remainder of the State and extends from the present 

 coast inland to the exposed area of the Triassic rocks. It is 

 made up of unconsolidated and undisturbed sediments, ranging 

 in age from Cretaceous to^ Recent. 



A glance at the geological column shown in Figure i, which 

 is drawn approximately to scale,- will show the relative position 



