Putnam Hill Strata. 33 



limestone, two specimens from that place are in my collection. — > 

 IJ foot. 



8. Very compact close grained, slaty sandstone in layers, from 

 half an inch to an inch in thickness. It contains a portion of fine 

 grained yellowish mica. The fracture is smooth, displaying dark 

 colored lines, a sixteenth of an inch in thickness, passing through 

 the stone in the line of stratification. The bed and surface-faces 

 are remarkably even, like roofing slate, for which purpose it has 

 been used, but is rather too heavy. — 7 feet. 



9. Pale blue, slaty clay — very fissile and loose in its texture. 

 Considerable quantities of argillaceous iron ore are found in detach- 

 ed nodules scattered through the bed, in flattened reniform masses. 

 On exposure, the surface becomes oxidized, and peels off in thin 

 concentric layers. The clay contains fine particles of sand and mi- 

 ca. Near the bottom of this stratum, fossil shells, in good preser- 

 vation, are found, imbedded in indurated masses of clay, indicating 

 a removal from their original bed. Those in my possession, belong 

 chiefly to the family of Pectens, with one Fusus. Figures are giv- 

 en in Nos. 12 and 13, (page 2 of the wood cuts,) with descriptions 

 added below. This bed is very extensive, and without doubt is 

 passed in boring for salt some distance down the river, as the whole 

 series dips directly to the S. and S. E. — 52 feet. 



10. Dark blue limestone — compact and hard in the upper part of 

 the stratum, lower part carbonaceous, loose and friable. It abounds 

 in fossil shells of the genera Terebratula and Gryphea ; it contains 

 also Encrini, the latter in branches, three or four feet in length, are 

 seen rising a little above the surface in the face of the stone, be- 

 tween the seams, and especially in weathered pieces. The animal 

 structure is replaced by pure crystallized carbonate of lime. When 

 the stone is fractured, these white cylinders appear in strong con- 

 trast with the dark mass of the rock in which they are imbedded. 

 Some specimens are three fourths of an inch in diameter, others 

 much smaller. Not having seen the base of these animals, I can- 

 not determine the species, but from the figures in Parkinson, should 

 call it the " Encrinus rectus." — The Terebratulse are small, and 

 many of them similar to No. 5, (page 2 of the wood cuts,) but so 

 closely imbedded as not to be removed without defacing the speci- 

 men. The Gryphea, resembles " Gryphea arcuata." — 5 feet. 



11. Bituminous coal — a thin bed of less than afoot, but of a fine 

 quality and brilliant fracture. Specific gravity about 1.30. There 



Vol. XXIX.— No. 1.5 



