1897.] KEW YORK ACADEMY OF SCIENCES. 105 



n.ary numbers forn, short distance above the red rock but usually 

 is comparatively rare in the higher portions. 



This deposit evidently passes the point of Castle harbor to 

 the south shore of the island ; the condition of contact is seen 

 along the south shore on the Military road already referred to. 

 At Devonshire bay, two miles beyond, is an interesting exposure 

 to which both Rice * and Nelson have called attention. The 

 succession is Sandstone, Marine Limestone, Limestone. 



The intermediate deposit, or marine limestone, covers the 

 broadly irregular surface of the limestone. It reaches to the 

 water-level, on the southwest side of the old fort, but is seven or 

 eight feet above it on the northerly side. The rock is hard in 

 the lower portions, but becomes soft above, disintegrating 

 readily and passing, as far as extent of consolidation is con- 

 cerned, very gradually into the overlying deposit. It is slightly 

 conglomerate in the upper portion. The structure is very sim- 

 ilar to that of the sandstone, the laminje being thin and inclined 

 in all directions. The hardness of the rock is not due to spray, 

 or to the washing of the present tides, since it is as marked on 

 the northerly, as on the southerly side of the fort. Livona, 

 Chama, Tellina a,r\c[ Area occur in prodigious numbers, the shells 

 of Livona being as large and as perfect as those dredged in Cas- 

 tle harbor, or in the shallows off the south shore. The other 

 shells give equal proof of having been deposited in compara- 

 tively still water. On the southerly side of the old fort, an 

 apparently complete physical break between the intermediate 

 rock and the sandstone is indicated b}^ a horizontal line, yet the 

 passage from the lower to the upper rock is extremely gradual, 

 while above the line and within the Helix zone, A7-ca and Ghama 

 were seen perfectly preserved, the open valves of Area, in one 

 case, being still attached. The condition, for a time at least, 

 must have been such as one sees at Tuckertown to-day, where 

 the dune is encroaching upon the bay. 



An excavation in the sandstone, on the north side of the fort, 

 reaching to this deposit, shows the former rock almost uncon- 

 solidated and holding great numbers of Livona in excellent con- 

 dition ; but it was not possible to determine whether or not 

 these are above or below the Helix-zone. 



On the road leading down to Hungry bay, a mile and a-half 

 beyond Devonshire bay, the junction between the sandstone and 

 the intermediate deposit is concealed, but the consolidated red 

 material is shown precisel}^ as at Peniston's quarry with the 

 sandstone at a few feet above it. The Helix bed is concealed. 

 The bluff at Elbow bay shows at eight or ten feet above the 



*Loc. cit., p. 13. 



