These boulders vary, from a few pounds up to two or three tons. They are mostly of a stratified silicious stone, some specimens compact enough to be called quartz rock, and others more or less friable like a sandstone.Small boulders of granite rock are occasionally met with. § The gravel stones found with the boulders are very coarse, and remarkable for the variety in their compo-/ sition.Quartz pebbles are most abundant, but those of slate, limestone, and sandstone are common; and those containing shells, corals, and other organic remains, are frequently met with. These fossils appear to belong to the Silurian rocks which are in place in the northwestern part of the State, and in New York and Pennsylvania; Towards the lower part of the Cape the gravel is not as coarse, and is more quartzose in its character; not only granular quartz, but impure agate, chalcedony, &c., being common. The strands near the steamboat landing, and at Town Bank^are noted localities for transparent quartz pebbles. These are much sought after by visitors, and are known as Cape May diamonds. The same varieties of pebble are also found in the banks and on the upland, but being covered with loam, they are not as conspicuous as they become after having been washed from the bank, and exposed for some time to the roll of the surf. § At Tuckaho^, casts and impressions of the common clam ( Venii^mercenaria) are found in cemented gravel. The cementing material is oxide of iron, and no traces of the lime of the original shell are left. Some of the casts are PHYSICAL AND GEOLOGICAL DESCRIPTION. 27 very perfect; and being supposed by many in the vicinity to be the^fleshy part of the clam petrified, they are known as petrified clams. . The locality where they are found most abundantly is upon the point of land between the two roads which lead from Tuckahoe, the one towards Petersburg, and the other towards Dennisville, and within a quarter of a mile of the village. They are usually within a few inches of the surface. The ground is nearly level, and six or eight feet above high water. About five miles south of Beesley's Point, and a short distance west of the sea-side road, on land of Mr. Jonathan Godfrey, is a locality of shell-marl. It was discovered several years since in the roots of a tree which had been blown down. It was also found in a water-hole. Mr. John Stites and myself, found it on the right of the road leading from the sea-side to the upper bridge across Cedar Swamp Creek. It was in a swampy hollow, and was covered by a foot of decayed leaves and muck, and one and a half feet of sand. The marl was a mixture of broken shells and blue mud, and only about a foot and a half thick.The shells appeared to be those of the oyster ; all very much broken. A few specimens of a little snail, or periwinkle {Buccinum obsoletwn) were found. It does not appear to be very extensive, as in trials since made in the vicinity it was not met with. The ground is several feet above tide, and is covered with trees and bushes. § A REMARKABLE fact in regard to b...