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greatest width, four miles northeast of Salem, it can be traced 

 over a breadth of three-fourths of a mile. Its thickness in the 

 same neighbourhood, as proved by a well sunk through it, is as 

 great in one spot as twenty feet ; though elsewhere in the same 

 vicinity it is not more than six or eight. Near Vincentown it 

 seems to be still less ; and upon the branches of Crosswick's creek, 

 it is reduced to less than one foot. The stratum preserves its 

 prevailing structure and position, at its several localities, leaving 

 us in no uncertainty as to its identity. 



Corn-position and Aspect. — This rock is usually a soft yellowish 

 or straw-coloured limestone, with a structure varying from sub- 

 crystalline to coarsely granular. It is often replete with organic 

 remains, the disintegrated shells and corals, and other fossils, 

 composing a considerable portion of the mass. Much of the 

 rock contains impurities, as sand, clay, and oxide of iron ; and 

 its value as a limestone is therefore very variable. At times it is 

 little else than a sandstone, in which the sand is cemented to- 

 gether by a trace of lime. It occurs with this character in loose 

 rounded masses, resting above the marl, at Woodstown. Again 

 it exists as a firm calcareous rock. This is its state in some 

 places near Salem, in Mannington township. In the several 

 accompanying analyses, the composition of the leading varieties 

 of the rock may be accurately seen. This limestone is nowhere 

 to be found in thick massive strata ; on the other hand, it occurs 

 only in thin horizontal beds, or irregular layers, not often more 

 than four or six inches thick, and commonly separated by a thin 

 parting of sand and carbonate of lime in small grains, to all 

 appearance an incohering mixture of the same materials that 

 form the rock itself The more calcareous beds have not un- 

 frequently some resemblance to some of the thin oolitic strata of 

 England, in consequence chiefly of the granular for'm of much of 

 the carbonate of lime; together with the innumerable fragments 

 of fossils which sometimes form almost half of the mass. Unless 

 attentively observed, this rock will appear much more sandy than 

 it actually is, owing to some of the carbonate of lime being in the 

 shape of small round yellow grains, like those of sand. Occa- 

 sionally, especially near the bottom of the stratum, where it 

 adjoins the marl, it contains a sensible proportion of the green 

 grains, sometimes in such abundance as to unfit it for being burnt 



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