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cealed by the superficial sands, or, what is rather more Hkely, 

 occupies what was originally a cove or bay in the midst of the 

 adjacent secondary strata, are points still obscure. At Elwell's 

 pits, about two miles northwest of Roadstown, the deposit shows 

 the following features : 



The superficial stratum of the neighbourhood is a rather coarse 

 yellow sand, five or six feet thick in the bank where the marl is 

 excavated. Beneath this, there is a layer four or five feet thick, 

 of a reddish-yellow clay, abounding in traces more or less obscure 

 of fossil shells in an extremely rotten and decayed condition. 

 Beneath this there is a bluish-green clay containing a multitude 

 of the same fossils in a somewhat less decomposed state, though- 

 very soft and tender. These two fossiliferous beds are in some 

 places twelve feet thick, and rest upon a dark greenish-blue 

 adhesive sand, bearing a close resemblance to the tenacious 

 sandy clay of the greensand formation. In the adjacent bank it 

 has the prevailing colour of that bed, and the same astringent 

 substances (copperas, &c.) which characterize it so generally. 

 The mass of loose friable clay, both yellow and green, exhibits a 

 very considerable proportion of carbonate of lime derived from 

 the decomposition of the shells, and the calcareous matter of 

 these fossils themselves. It is a marl calculated to be especially 

 beneficial upon the very sandy land of the vicinity. It will be 

 found valuable as a fertilizer in proportion to the lime which it 

 contains, the crumbly state of the shells, and its freedom from 

 sand. 



The description here given of Elwell's marl, will apply pretty 

 well to the other marls excavated upon the same streams, with 

 this reservation however, that the shells in some localities are 

 less rotten and in their nature less destructible, which is the case 

 with those of the oyster. These occur in one part of the deposit 

 at Davis's bank; and also in the greater number of the openings 

 higher up the stream, where the clay seems to possess a rather 

 larger share of sand. 



Another stratum of the same geological age, occurs about a 

 mile and a half southeast of Fairton, and near the Rattlesnake 

 run. It is a very thin bed of a similar bluish clay, containing a 

 small proportion of decomposed shells, and resting, like the Stow 



