gravel deposits are locally 135 feet thick, the great mass of the clay is unavailable.

At present the clay along Cheesequake creek is being dug only by Leonard Furman and H. C. Perrine & Son. The former mines his clay by shafts and drifts, the latter firm, controlling several banks, works in open pits. All in all, the stoneware bed is worked much less than was the case twenty-five years ago.

SAND BED, NO. 3.

Underlying the Amboy stoneware clay and overlying the fire clays, which are dug at Sayreville and Burt Creek (to be described below), there is a thick deposit of quartz sand. The lower portion of the bed is exposed in most of the excavations made to reach the underlying fire clay, while the upper part has been penetrated by a few borings made in the bottom of the overlying stoneware-clay beds. The entire bed is nowhere exposed in a continuous section.

In general the material is a loose, clean, quartz sand, often coarse and occasionally even approximating fine gravel. Much of it is sharp and angular and of value for fire, foundry, and building sand. The sand pits of Sayre & Fisher, Edward Furman, William Albert, Whitehead Brothers and J. R. Crossman, at Sayreville and Burt Creek, are located in this bed, which underlies the high ground south of the Raritan river and northwest of the Camden & Amboy Rwy., between Sayreville and South Amboy. A heavy bed of yellow gravel (Pensauken) forms the tops of the hills, but the sand underlies the gravel at an elevation of about 90 feet. Locally, however, it contains some thin lenses of clay, such as are seen in the upper part of Whitehead's bank (69), west of Burt Creek. The sandy clays formerly dug along the shore near George street, South Amboy, seem also to belong here, as they are too low for the Amboy stoneware clay.

As already noted in connection with the stoneware clay, the upper part of this sand member is, in some pits, a black, lignitic sand or sandy clay. This was reported to be the case at Perrine's poorhouse bank (81), one of the shafts at the old Ernst property

(80), and at several of the abandoned workings near the head of Crossway brook. At other points the Amboy stoneware clay rests upon clean, light-colored, quartz sand. So, also, the basal portion is variable. At some banks a clean, quartz sand rests upon the undulatory surface of the fire clay beneath. In other banks or even in other parts of the same bank, a black sand or sandy clay, or alternating layers of black sand and clay with a maximum thickness of 15 feet occur between the fire clay and the quartz sand. These beds are more or less lignitic, and Cook and Smock1 report finding numerous well-preserved leaf impressions in some layers. Locally also, small masses of amber are found in these dark clays immediately above the fire clay. These dark, sandy clays are best exposed at the J. R. Crossman banks (65 and 66), J. R. Such's bank (67), and in several banks on the old E. F. & J. M. Roberts property, north of Burt Creek, now owned by Sayre & Fisher.

Judging from the width of outcrop of this sand bed, where its boundaries can be well determined, and assuming that its dip is the same as that of the adjoining beds, 35 to 40 feet per mile, it has a thickness of 45 to 50 feet. Exposures of 30 or even 40 feet are not uncommon in some of the fire-clay banks near Sayreville and Burt Creek. At Whitehead's clay pit (69) the base of the sand has an elevation of about 38 feet above tide. Thence the sand is apparently continuous to a height of 90 feet near the crest of the hill just east of the pit. This thickness (52 feet) agrees fairly well with that estimated from the dip, when the irregular character both of the upper and lower beds of clay are considered. Fifty feet seems a fair measure of the thickness of this member where both the adjoining clay beds are moderately well developed.

SOUTH AMBOY FIRE CLAY.

The South Amboy fire-clay bed lies beneath the quartz sand bed just described. Its main outcrop is on the northern and western slope of the high hills, which lie south of the Raritan river.

1 Clay Report of 1878, p. 69.

between Sayreville and South Amboy. It is also found north of the Raritan, in the high ground north of Eagleswood and Florida. Grove. It has not been recognized west of South river, although, if present at all, it should occur in the high slopes bordering the stream between South River village and Old Bridge. The upper part of these slopes are, however, gravel (Pensauken) and the lower are quartz sand, with some thin clay laminæ.

South of the Raritan and east of Sayreville the bed has a narrow outcrop along the lower slope of the hill. Since it dips gently to the southeast and the surface rises steeply in the same direction, the clay bed occupies but a narrow belt at the surface, and, when followed into the hill, is soon deeply buried by the overlying Cretaceous sands (No. 3) and the much more recent Pensauken gravel. North of the Raritan the surface is more nearly level, or slopes in the same direction as the dip of the clay bed, so that the latter occurs near the surface over a wider area. These facts are shown on Plate XI, where the zone of outcrop is shown, as well as the probable extension of the clay beneath the overlying beds.

The South Amboy fire-clay bed is in general a white, light-blue, or red-mottled clay. Locally some portions of the bed are quite dark and contain bits of lignite. The following succession has frequently been observed, beginning at the top: (a) Sandy white to buff-colored clay, (b) blue fire clay, (c) sandy red-mottled clay. These are not distinct layers, but gradations from top to bottom in the one bed, and similar horizontal variations frequently occur. The upper and lower portions are often more sandy than the middle part, but in at least two widely separated localities, McHose Brothers (45) and J. R. Such (67), one north and the other south of the Raritan, beds of loose quartz sand, varying from 2 to 12 feet in thickness, are known to occur in the middle of this bed, separating the fire clay into a top and bottom layer. Mr. Such also reports finding in one portion of his bank a lense of fine clay in the middle of this intermediate sand layer. It is apparent, therefore, that this clay bed shows considerable variation in different banks. "Sulphur balls,' or round ball-like aggregations of pyrite crystals, are found in many places in this bed. They occur irregularly in all parts of it in the rich white, or fine fire clays, just as in the inferior red clays. These are from

I to 4 inches in diameter. Frequently the outer shell or periphery is completely changed to ferric oxide, while the interior is still unchanged sulphide of iron. Pyrite in smaller lumps and fragmentary pieces is also quite common, and diffused throughout the clay of the whole bed as worked in some places."1

In the banks of J. R. Crossman (65, 66), J. R. Such (67) and some of the old excavations on the Kearney tract, north of Burt Creek, a black, lignitic clay, or alternating bed of clay and sand occurs immediately above the fire clay proper and is included with the fire clay on the map. Small pieces of amber occur near the base of the black clay in some localities. The surface of the fire clay beneath this black clay is often sharply undulatory, so much so as to suggest some erosion of the fire clay previous to the deposition of the black clay. The interruption to continuous deposition was probably not long, and the erosion is no more than could have been accomplished by shifting tidal currents. At most exposures, however, the fire clay is overlain either by the quartz sand (No. 3), which belongs to the Raritan series, or by the much more recent Pensauken gravel or red glacial drift. In the latter case the overlying Cretaceous sand, and often the upper portion of the clay itself was removed in the long period of erosion, after the formation of the Cretaceous beds, and before the deposition of the Pensauken gravel or the still later glacial drift. But even where the clay is overlain directly by the quartz sand (No. 3), its upper surface is sharply irregular and the bed varies greatly in thickness, indicating that there was at least a brief interruption in sedimentation and some erosion of the clay, as a result of the changed conditions and swifter moving currents, which began the deposition of the sand.

As may be inferred from what has been said, the South Amboy fire-clay bed presents great variations in thickness. At Sayre & Fisher's bank (273) variations of 15 feet in the height of the surface in a horizontal distance of 30 feet have been observed, with corresponding variations in thickness. In a few banks a thickness of 30 feet is sometimes found, but the average is much less than this. In not a few localities the clay is absent entirely.

'Report on the Clay Deposits of New Jersey, 1878, p. 67.

At Charles Edgar's pits (268) the average thickness is 15 feet; at Sayre & Fisher's (267) 8 feet, while in the adjoining railroad cut near Van Deventer's station, on the Raritan River railway, it is absent entirely or represented only by a sandy clay 1 or 2 feet thick. In Whitehead Brothers' banks, between Sayeville and Burt Creek, the thickness varies from 5 to 15 feet, but in the isolated hill just north of bank 69 (see map) quartz sand apparently occupies the horizon of the clay, which is absent. So, too, farther east, J. R. Crossman's and J. R. Such's clay (65, 66, 67) ranges from 8 to 30 feet, including all grades. In the various pits on the old Kearney tract (60, 61, 62) the clay has been found to run from 8 to 20 feet, but at Crossman's sand pit (63), and in the isolated hill just south of his dock, there is no sign of the fire clay, its horizon being occupied by coarse quartz sand. One-fourth mile east, however, in a new bank of the Sayre & Fisher Company (274), 12 to 15 feet of white and red-mottled clay is found at an elevation of between 70 and 58 feet above tide, while a few rods still farther east a dark-blue terra-cotta clay occurs at a corresponding elevation. For two-thirds of a mile farther north along the western face of the hills, a number of small openings have been made in search of the fire clay, but it is absent altogether, or is too thin to be worked profitably. Many years ago, however, it was found at an elevation (top) of 60 feet in considerable thickness about one-half mile southeast of Kearney's dock, where a large area was dug over. East of this point the clay cannot be traced continuously, but the sandy clay (4 to 7 feet thick) dug by George A. Thomas (56) at South Amboy apparently corresponds stratigraphically to the fire clay.

North of the Raritan river this clay bed is dug chiefly by McHose Brothers (45) north of Florida Grove, and by Henry Maurer & Son (42). At the McHose bank the clay varies greatly in thickness and quality. In one part of this bank there was found a black, lignitic clay, beneath which the fire clay was supposed to exist, but instead a boring penetrated between 30 and 40 feet of sand. At this depth 9 feet of blue and buff clay were found, but at too low a level to be correlated with the Amboy fire-clay bed. In adjoining portions of the bank 15 to 25 feet of clay of various grades are found, all belonging to the fire-clay horizon. Maurer's