at least during the closing stages of the Glacial period the southern portion of the State stood from 40 to 60 feet lower than at present, at which time the waves and streams constructed the terraces just mentioned.

They are for the most part composed of gravel and sand. In certain localities, however, they contain workable beds of clay, and in many places they are covered with the clay loam already described (pp. 121-2). To the material of these terraces south of the region where it is glacial, the name Cape May formation has been given. It may be equivalent in age, in whole or in part, to the glacial and aqueo-glacial clays just described, but owing to the different manner of accumulation, its clay beds are separately considered.

Localities. As already indicated, the Cape May formation is partly marine and partly river made. The land stood 40 to 60 feet lower than at present, and estuaries were formed at the mouths of all the streams. In several of these estuaries there seems to have been a certain area where the conditions favored the accumulation of beds of clay. Such conditions apparently prevailed in Cohansey creek, near Bridgeton; in Maurice river, near Buckshutem, south of Millville; in Great Egg Harbor river, at High Bank Landing, near Mays Landing; in the Delaware, near Kinkora, and perhaps also at Edgewater Park. At these points the clay is sandy, usually dark in color, due to carbonaceous material, and somewhat pebbly. It is commonly covered with several feet of sand or gravel, or both. Near Port Elizabeth it is overlain by a layer of oyster shells of recent age, 2 feet thick.1 The beds of clay are apparently of limited extent and grade horizontally into sand or gravel. This is well shown at the line of old pits on the right bank of Cohansey creek below Bridgeton. The maximum thickness observed was about 17 feet at Hess & Golder's pit, near Buckshutem, on Maurice river.

At the time of our investigations these clays were being dug at Hess & Golder's pit (181) and A. Burchem's yard (180), both on the Maurice river, near Buckshutem. They were also formerly dug by Isaac Mulford, near Millville; by Isaac Hil

1N. J. Geol. Surv., Ann. Rep. 1878, p. 64.

liard, near Buckshutem, and by B. F. Lupton, at Bridgeton. The black clay overlying a yellow quartz sand resembling the Pensauken at Martin's brickyard, Kinkora (115), is clearly a comparatively recent deposit, and may belong in the Cape May formation.

At Henry C. Adams' clay pit and brickyard at Edgewater Park (127) 8 feet of yellowish and black clay, overlain by several feet of wind-blown sand, rests upon a reddish-brown sand, which is apparently of glacial derivation. The clay is a local deposit, grading laterally into sand, and in places contains great numbers of rootlets, which suggest a swamp or estuary deposit of comparatively recent origin, although the surroundings are not at all swampy at present. On the contrary, the clay bed is located on the top of a gentle swell, but its elevation is not more than 40 feet above tide, so that it is within the limits of an area which was submerged during and since late Glacial time. The clay is either Cape May or later in time of origin.

In addition to the above-mentioned areas, the clays at Belle Plain (188), Woodbine (189) and Bakersville (275) are thought to belong to this horizon.1 At these three localities the clay occurs at elevations of 40 feet or less. It forms shallow, sandy deposits, somewhat pebbly and overlain by several feet of sand or gravel. They are apparently thin clayey lenses in the sand and gravel which form the great mass of the Cape May formation. The Bakersville deposit is said to cover something over 200 acres, but the extent of the other beds is not known. It is not unlikely that similar deposits, at present undeveloped, may be found at points along the coast within the elevation-50 feet of the Cape May formation. Owing, however, to a surfacing of sand and gravel, their presence can only be detected by boring.

The clays of the Cape May formation are of value chiefly for the manufacture of red brick or drain tile. There are, however, some small lenses of buff-burning clay.

It is not impossible that the clays at Belle Plain and Woodbine belong to the Cohansey formation, although in the absence of any decisive evidence we have placed them in the Cape May, chiefly on the basis of their elevation.

PENSAUKEN.

The Pensauken formation has been somewhat fully discussed in the previous reports of the Survey. It is predominantly a sand and gravel formation occurring chiefly in two belts. "One of these runs across the State in a northeast-southwest direction from the head of Raritan bay nearly to Salem; the other runs along the east side of the State from the vicinity of Asbury Park to Bridgeton. The former belt is narrow and clearly defined, and within it the formation occurs in a series of closely associated patches, some of which are large and some small; the latter belt is wider and less well defined, the patches of the formation being more widely separated."2 The Pensauken formation is believed to be contemporaneous in age with an earlier ice epoch than that to which the Belvidere-Perth Amboy moraine is referred. The extent to which the formation has been removed by erosion, and the deeply dissected condition of the remnants, indicate a much greater age than the Cape May formation or the great mass of glacial drift.

The Fish-House clays.-Although this formation is predominantly sand and gravel, yet at Fish House (137), a few miles north of Camden, there are thick beds of black clay which are apparently intercalated in the sands of this formation. Since these clays are somewhat fossiliferous, they have long attracted the attention of geologists, and many diverse views have been held as to their age. A few years ago a series of borings was made to determine their extent, and the data thus obtained made it possible to fix their stratigraphic position. The sections were carefully examined at the time by Lewis Woolman, and the following facts both as to stratigraphy and fossils are mainly summarized from his report.3

In the excavations the clay attains a thickness of 27 or 28 feet. The upper 2 or 3 feet is yellowish in color, as is also the

3

* Ann. Rep. of the State Geologist of N. J., 1896, pp. 201-244.

basal foot. The great bulk of the clay, however, when freshly dug, and before weathering, is black. Immediately beneath the clay and forming the floor of the excavation is a layer of "ironstone" a few inches thick, beneath which occurs coarse yellow sand (Pensauken). Above the clay occurs a few feet of clayey loam, usually with a well-marked line of pebbles at its base.

In the southeastern portion of the excavation a wedge-shaped mass of white plastic clay of Cretaceous age was found. The black clay abutted against this, and, toward the thin edge of the wedge, overlay it unconformably. The same white Cretaceous clay is also exposed in adjoining excavations on the south at the same level as the black clay, which is there absent. Above the white clay occur sand and gravel deposits continuous with those which overlie the black clay. The facts clearly establish the recentcy of the black clay as compared to the white Cretaceous clays.

The facts, as shown in the excavations, are supplemented by the records of over 50 borings, from which it appears that the black clay terminates rapidly to the south, partly by abutting against the underlying Cretaceous clay, and partly by thinning out and giving place to gravel and sand. It extends northeastward almost to Delair avenue, occurring on both sides of the river road, but its maximum known thickness (311⁄2 feet) is apparently near the eastern portion of the present excavation. Towards its limits it diminishes greatly in thickness, contains lenses of sand or gravel, and is overlain by gravel which is unquestionably of Pensauken age. From northeast to southwest its length is about 3,800 feet, and its breadth, so far as known, 1,500 or 1,600 feet. It evidently occupies a somewhat circumscribed area, wherein during Pensauken submergence, unique conditions (for that epoch) favorable to the deposition of clay prevailed.

Fossils. Near the base of the clay there is a bed containing numerous casts of fresh-water mussels belonging to the genera

That is in such a way as to show that the white clay had been eroded and partly removed after it had been deposited and before the black clay was formed.

N. J. Geol. Surv., Ann. Rep. for 1896, pp. 205-212.

Unio and Anodonta, which bear a close resemblance to living forms. Teeth and portions of the skull of an extinct horse have also been found, as well as a few other vertebrate remains and some plant forms. The fossil evidence is all indicative of the comparative late age of those clays, but is not sufficiently refined to do more than corroborate in a general way the evidence of age derived from the stratigraphy.

THE BRIDGETON FORMATION.1

The next older formation than the Pensauken recognized in New Jersey is the Bridgeton. Like the Pensauken, it represents a period when the State was depressed below its present level, so that areas now 200 feet and less above sea were for the most part submerged. Like the Pensauken, it is also chiefly gravel and sand; like the Pensauken, it occurs in a series of isolated patches, large and small, which are but remnants of what was once a continuous formation. These remnants are most extensive in the southeast parts of Burlington, Camden, Gloucester, and Salem counties and the northern portion of Cumberland. Here the formation in general caps the hills and forms considerable deposits on the broad interstream surfaces.

The formation locally contains a few thin seams of clay near its base, interbedded with coarse sands and even gravel. So far as known, however, these are never of commercial importance and are nowhere worked.

1The exact age of the Bridgeton formation is not beyond question. It has not been positively determined whether it is Pleistocene or earlier, and, perhaps, never can be definitely settled. The weight of available evidence favors its correlation with the earlier or high-level Columbia of the District of Columbia.