cross-bedded, and this, together with the irregularity of the "feldspar" lenses, indicates that the deposit was made in rapidly moving water, where shifting currents brought about constantly recurring conditions of deposition, erosion and re-deposition.

It has been stated that the "feldspar" beds are entirely unstratified, and that in this respect they are in marked contrast to the other beds of the Raritan. It is true that in these lenses there is no stratification or lamination of such a nature as to separate the quartz pebbles from the decomposed feldspar masses. The two are most intimately mingled without a trace of the alternation of clay seams and sand layers, which is sometimes seen in other portions of the Cretaceous. Nevertheless, there are definite, though not always obtrusive, lines of stratification in the "feldspar" lenses, and there is plain evidence of its deposition in water. (Plate XX, particularly Fig. 1.)

As was noted above, the quartz pebbles are somewhat rounded, and hence have suffered at least a moderate amount of wear during transportation by streams or waves. The clayey or kaolinized material is now for the most part so soft that it is difficult to imagine how it could have been transported any distance in its present condition along with the hard quartz without complete disintegration. This difficulty is met, if it be assumed that the alteration of the feldspar pebbles to the clay masses has taken place subsequent to their deposition. The pebble-like form and incomplete alteration of a portion of them accords with this assumption, but the irregular shape and the manner in which much. of the clayey material surrounds the quartz pebbles are apparently inconsistent with this hypothesis. It must be borne in mind, however, that, as the feldspar changes to kaolinite, water is absorbed and there is some increase in volume. This swelling may account in part for the irregular outlines of the clay particles. To some extent, also, settling of the beds since deposition may have squeezed the clayey material around and between the quartz pebbles, but these explanations do not seem wholly adequate. If the material were derived from a partially decomposed rock composed of quartz and large feldspar crystals, it may be assumed that some

of the feldspar would be hard enough to resist much wear, and be finally deposited in a firm condition. Part may have already been completely kaolinized and formed clay lumps, in which subangular quartz grains were already imbedded or became imbedded during transportation. The clay lumps would of course have been greatly diminished in size by transportation even a short distance only, but may still not have been completely worn away. But whatever may be the difficulties in determining the exact method in all details by which this material was formed, its ultimate derivation from a quartz-feldspar rock, and its deposition in its present position by water cannot be questioned.

The "feldspar" is used chiefly in the manufacture of fire brick, but it is not dug so much as formerly. The main workings at present are the banks of Valentine (40), Maurer (41), Staten Island Clay Company (32), and Remy (242), all north of the Raritan river. A few pits have been dug near the shore northwest of South Amboy, but they are not worked at present. Since the "feldspar" occurs as lenses, and not as a continuous bed, it is impossible to map it definitely. Its occurrence, however, is limited to the zone between the black clay of the Woodbridge bed and South Amboy fire clay, so that its general horizon can be definitely fixed.

The so-called "kaolin" is not in any sense of the term a kaolin, although always so named in this district. It "is a micaceous sand, consisting of very fine-grained, white quartz sand, mixed with a small and varying percentage of white mica, in small flakes or scales, and a very little white clay. The mica is, however, conspicuous, and gives the mass a glistening appearance and a somewhat soft and soapy feel, but the sand is largely in excess, constituting from 60 to 90 per cent. of the mass in the more clayey and micaceous specimens."

THE WOODBRIDGE CLAY.

General distribution.-Beneath the "Feldspar-Kaolin" sands, there occurs the Woodbridge clay bed, the most important and most widely worked of all the subdivisions of the Raritan forma

tion. Its importance is due to its great thickness (50 to 80 feet where not eroded), to its wide outcrop, and to its character.

It has been opened in four somewhat distinct areas, a) south of Woodbridge, b) north of the Raritan river from Florida Grove to Bonhamtown, c) south of the Raritan from South Amboy to Sayreville and south to Jas. Bissetts' brickyard on South river, d) at South River village and west to Milltown. The four districts may be spoken of briefly as a) the Woodbridge area, b) the Sand Hills area, c) the Sayreville area, d) South River area. The Woodbridge and Sand Hills areas are separated from each other by a belt of hills, the tops of which are formed either by thick deposits of glacial drift or by the higher members of the Raritan formation, i. e., the "Feldspar-Kaolin" sands, and the South Amboy fire clay. Whether or not the Woodbridge clays are continuous across the belt beneath these later deposits, or whether the core of the ridge of hills is formed by the Triassic red shale, as may be inferred from an isolated knoll of this formation between Eagleswood and Spa Spring is uncertain. The Sayreville and South River areas are separated from each other, and from the other two by the deep trenches of the Raritan river and of its tributary, South river. The clay bed was beyond a doubt formerly continuous between them, but the excavation of the river valleys has dissected it and removed a large part of the clay, so that, although these rivers, by affording navigable waterways and cheap means of transportation, have greatly enhanced the value of the clays along their valleys, yet their existence has been accomplished by the erosion and removal of much of the clay stratum.

Thickness.-The thickness of this member varies from about 50 feet in the vicinity of Woodbridge to 80 feet near Spa Spring and Maurer, as shown by borings, but this amount of clay is nowhere exposed in any one bank. At many of the banks near Woodbridge, particularly the more northwesterly openings, the upper part of the bed has been eroded away, and only the lower 15 or 20 feet remain. In fact, there has been a varying amount of erosion wherever the yellow Pensauken gravel or the red glacial drift lies upon the clay (Plate XXI, Fig. 1). In some cases also huge masses of the clay many feet in diameter have been included in the drift, as in Plate XXI, Fig. 2. But where the black, lam

inated clay at the top is overlain by a white, micaceous sand, that is by the next higher Cretaceous bed, there has been no erosion of the Woodbridge clay (Plate XX, Fig. 2). This is the case in most of the banks about Maurer and Keasbey, and at Sayreville. Here, however, the base of the clay lies so deep that it below sea level and is reached only by borings. The thicknesses given above make due allowance for the upper layers where they have been eroded, or are based on the data furnished by borings where the base of the clay is not exposed.

The Woodbridge clays do not form a homogeneous bed, but are made up of many layers of varying quality. At the top there is a black, lignitic clay with alternating seams and layers of sand. These were called by Dr. Cook the "laminated clays and sands." At the base there is a bed of fire clay,-Cook's Woodbridge fireclay bed. In some areas certain beds just above the fire clay have a marked individuality, and can be recognized in adjoining banks. Elsewhere the corresponding layers are not sharply separable from the laminated clays and are included with them.

The black laminated clays.-As above noted, the upper portion of the Woodbridge clay bed consists of a succession of beds of black clay carrying some lignite and pyrite, and alternating with thin seams of white quartz sand, which is often darkened by disseminated bits of lignite. There is no order or regularity in this alternation. Both the clay and the sand layers vary in every conceivable manner in thickness and position. Locally the clay beds are thick and the sand is reduced to leaf-like partings; elsewhere the reverse may be true, and the greater part of the section may be sand, although the clay predominates on the whole. Layers of clay from one-eighth to one-fourth of an inch in thickness, separated by seams of sand scarcely thicker than a sheet of stiff paper, are of common occurrence. It is utterly impossible to trace individual layers any distance, or to identify any particular portion of this member in a small exposure, except locally in the case of some beds just above the fire clay, as noted in the preceding paragraph. Lignite and pyrite are irregularly disseminated through the entire mass, occurring in nearly every layer in at least small quantities and forming a large part of some beds. Concretions