54' FOURTH REPORT— 1S.'34. 



and sometimes the clay and marl are mingled. Beneath the 

 stratum of pure greensand or marl, a dark ferruginous sand- 

 stone, containing many of the same cretaceous fossils which 

 abound in the marl, has occasionally been reached. This, M'hich 

 is the lowest bed of the group, exhibits a striking resemblance 

 to some of the ferruginous sandstone and conglomerate of the 

 lower greensand of England, and serves to indicate how similar 

 in general the chemical and mechanical circumstances appear to 

 have been during the same geological period on both sides of the 

 Atlantic. 



Some localities in New Jersey present " beds of a siliceous 

 gravel, the pebbles varying in size from coarse sand to an inch 

 in diameter, and either loose, or cemented by brown oxide and 

 green phosphate of iron ; the mass containing sometimes a pro- 

 fusion of fossils." When it occurs, it usually rests above the 

 marl. 



The last bed to be described is a sandstone deposit, resting 

 above all the deposits here enumerated. It occurs rarely in situ, 

 except as the top stratum on most of the detached ridges and out- 

 lying hills, but it is found, mingled with the general diluvium, 

 in worn and broken fragments over nearly all the denuded tracts. 

 It consists of sand and minute pebbles of quartz united by a 

 dark brown ferruginous cement, the whole rock having a very 

 perfect resemblance to the ferruginous conglomerate of the lower 

 greensand at Lockswell Heath in Wiltshire, England. It is 

 destitute, however, of fossiliferous impressions and casts. Some- 

 times it incloses a sensible quantity of the green grains, which, 

 however, have no effect in modifying its colour. 



The sand composing the rock has often the character of a 

 coarse triturated beach sand ; this is especially seen in the 

 quarries about four miles east of Burlington, where it occurs in 

 a regular horizontal bed many feet thick. 



The diversified deposits of sand, marl, clay, sandstone, gravel, 

 &c., described above, assume a great variety of mineralogical 

 character, resulting from their various conditions of induration, 

 and their almost endless intermixture. The most fossiliferous 

 beds are the marl, and the marly sand which usually reposes im- 

 mediately upon it. In the marl the organic remains, consisting 

 of shells, zoophytes, and bones oi Reptilia in great number, ap- 

 pear to have been preserved in a very perfect state from the 

 imperviousness of the greensand to water, which descends 

 with facility through the ai-enaceous beds above, but is invariably 

 arrested and thrown out along the upper surface of the marl. 

 The water percolating through the overlying marly sands has 

 effected a change upon the fossils, leaving them in this bed 



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