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THE VEGETATION OF THE HACKENSACK marsh: A TYPICAL AMERICAN FEN 



evident from the fact that at the present time the glacial drift lies just above 

 it. The drift is mixed with and covered by a deep stratum of laminated clay 

 which contains gravel, boulders, and calcareous nodules in abundance. The 

 composition of the clay and its position just above the glacial drift lead one 

 to beheve that it was deposited in standing water left by the retreating Pleis- 

 tocene ice-sheet. The thickness of this clay stratum varies from 85 to 250 

 feet, the greater thicknesses being due to the presence of large quantities of 

 drift. 



Just above the laminated clay occurs a thin layer of alternating sand and 

 yellow loam, averaging 2 to 3 feet in thickness. The loam corresponds exactly. 

 to that found exposed at many places adjoining the Hackensack marsh, and 

 it is quite probable that the loam, now covered, was at one time continuous 

 with that exposed in neighboring regions. The presence of the sand at dif- 

 ferent places is puzzHng. It may be the remains of the old sandy sea-beach 

 upon which the present marsh was built by the action of the tide, but this 

 is not at all certain (Fig. 2). 



Above the shallow layer of sand and loam there is a much deeper stratum 

 of black, soggy muck which ranges from a depth of only i foot to 70 feet in* 

 some places. This is chiefly a mixture of dark silt, organic matter, water, and 

 gases (CH4, CO2, H2S, etc.), and probably owes its origin to long action of 

 the tidal water in depositing silt and also to the accumulation of plant 

 remains. 



Perhaps, also, after the final withdrawal of the great ice-sheet from the 

 glaciated regions of America, a shallow inland bay or arm of the sea was left 

 where the. Hackensack marsh now is. The flat margins were, no doubt, wet 

 enough to support marsh vegetation, and as the time went on this vegetation 

 came to fill the bay, leaving open the tortuous tidal channels, or creeks, which 

 intersect the surface of the present marsh. The fact that stumps with roots 

 of the white cedar, Chamcecyparis thyoides, are found imbedded in the muck 

 indicates (Fig. 3) that in recent times the marsh surface in places was above 

 tide-water and covered with groves of trees,* and for the reason that this tree 

 has been reported near Newark by W. M. Wolfe. The obliteration of most of 

 this acid swamp was brought about probably either by a resinking of the shore 



* Cf. somewhat similar conditions of the encroachment of salt marshes on Chamaecyparis 

 trees in Massachusetts, viz., Bartlett, Harley H.: The Submarine Chamaecyparis Bog at Woods Hole, 

 Massachusetts, Rhodora 11: 221-235, December, 1909. 



