THE VEGETATION OF THE HACKENSACK 

 MARSH: A TYPICAL AMERICAN FEN 



By JOHN W. HARSHBERGER and VINCENT G. BURNS* 



INTRODUCTION (V. G. B.) 



THE Hackensack River, which may be regarded as a branch of the 

 Passaic, rises in the northeastern corner of the State of New Jersey, 

 and drains a region of considerable extent lying along the west slopes 

 of the Palisade Range. From the town of Hackensack south to the outlet in 

 Newark Bay the river occupies a valley approximately four miles in width 

 and eight miles in length, which is largely filled by a brackish tide-water marsh. 

 On the west the marsh is separated from the valley of the Passaic by a long, 

 low ridge of reddish-brown sandstone (Newark System of Triassic), and on 

 the east a^parallel ridge of igneous rock (Palisade Diabase of Triassic) sepa- 

 rates it from the Hudson River. Outcroppings of the latter — igneous intru- 

 sion — are found in the center of the valley in the form of two large rock masses, 

 known as Snake Hill and Little Snake Hill (Fig. i). Owing to the scarcity 

 of connected outcrops over the entire area of the Hackensack Valley, no 

 definite stratigraphic succession of the rocks underlying the marsh has been 

 determined up to the present time. However, it is stated in the Geologic 

 Atlas of New Jersey, pubKshed in 1908, that the greater part of the Hacken- 

 sack marsh is known to lie ''in a deep depression excavated mainly in shales 

 which have been reached by some of the wells." Numerous borings about 

 Newark, Hackensack, and neighboring points have given information con- 

 cerning the layers which occur above the underlying rock. Data obtained 

 from records of these borings, in the Geologic Atlas of New Jersey (1908) and 

 from Mr. Hewitt Crosby, Reclamation Engineer of New York City, make 

 possible the following interpretations of the foundation of the marshes. 



It is definitely known that the marsh is underlaid by a layer of Triassic 

 red shale, because this rock has always been reached wherever deep borings 

 have been made. That this shale constituted the main part of the exposed 

 rock in the region of the marsh just prior to the Pleistocene Glaciation seems 



* The separate parts of this contribution to botanic science are indicated by the initials of 

 author contributing that part, viz., J. W. H. and V. G. B. 



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