28 GEOLOGICAL SURVEY OF NEW JERSEY. 



species of plants are considerably more numerous in these northern 

 districts than farther south, and they are to be associated with those 

 of more northern regions, and of Europe and Asia. 



The southern parts of the State are especially characterized by far 

 greater uniformity in the characters of the topography and of the 

 soil. There are broad sandy plains, lying as a whole but slightly 

 above the sea, though locally rising in hills to 300 or 400 feet, con- 

 taining very few rock outcrops and abundantly supplied with deep 

 swamps. The soil is sandy or loamy throughout almost the entire 

 region, locally enriched by the greensand marl outcrops along a belt 

 a few miles in width, stretching from Keyport and Deal Beach on the 

 northeast to Salem county on the southwest. This sandy and loamy 

 soil is abundantly supplied with beds and local deposits of yellow 

 gravel, and is as a whole of a light color, from which its name of 

 Yellow Gravel has been derived. It is more ancient in deposition 

 than the Glacial Drift, and supports a very characteristic but more 

 limited flora, whose affinity is with that of the more southern Atlantic 

 Plain, of which, indeed, this region is topographically and geologic- 

 ally a northern continuation. This group of plants is characteris- 

 tically American, very few of its members growing naturally beyond 

 our continent. 



Our flora may thus be divided with considerable accuracy into a 

 northern and a southern, whose present distribution has been deter- 

 mined by differences of soil and climate. As would naturally be 

 expected, there is considerable overlapping of these two groups of 

 plants in the portions of the State where they come together, but the 

 conclusion reached at the time the Preliminary Catalogue was writ- 

 ten, that they are most naturally separated by the glacial terminal 

 moraine, appears to be substantiated. 



Certain species of the northern flora do extend, however, to a con- 

 siderable distance south of the glacial drift, some of them coming to 

 the southern margin of the Triassic red sandstone, while others are 

 found in greater or less abundance along the outcropping layers of 

 the Cretaceous greensand marls in an area a few miles in width along 

 the lower Delaware river through Mercer, Burlington, Camden, Glou- 

 cester and Salem counties. This distribution is undoubtedly deter- 

 mined by soil characters. 



Besides these two main divisions of our flora there is another, 

 which may be termed the marine and coast group of plants, species 



