Warren and Sussex counties in Kittatinny mountain and the lower country on the west, and also in the Green Pond-Bearfort mountain region. The shales are nowhere utilized, and no tests have been made of them in this investigation. They are for the most part sandy and unpromising. CAMBRIAN AND ORDOVICIAN. The Cambrian and Ordovician rocks are limestones and shales with some beds of sandstone and quartzite. They occur chiefly in Warren and Sussex counties in the great Kittatinny valley, between the Kittatinny mountain on the northwest and the Highlands on the southeast. They also occur within the Highland area in the valleys of the Musconetcong and Pohatcong, the South Branch of the Raritan northeast of Califon, and in the Green Pond mountain region. They also are found in a few small areas southeast of the Highlands between the crystallines and the Trias red shale, the largest of these isolated areas being in the vicinity of Clinton and Pattenburg. Southwest of the terminal moraine, which marks the southward border of the region covered by the ice of the last Glacial epoch, the rocks are in places somewhat deeply weathered and buried beneath the products of their own disintegration. The limestone commonly weathers into a yellow sticky clay, containing more or less abundantly the insoluble black cherts or flints, which occur in it. Locally beds of clay may thus be formed, partly by the decay of the rock beneath and partly by the wash from similar material on higher slopes. The smooth clay on the property of L. T. Labar, near Beattystown (Loc. 283), has probably originated in this way, although some of it may belong to a very early glacial drift. At Alpha (Loc. 278), near Phillipsburg, the Portland cement rock (Trenton age) is covered by 3 or 4 feet of yellow sticky clay, with a soapy feeling, which contains occasional small masses of vein quartz, etc., and which was derived from the cement rock 'See Chapter XIX for physical tests of these clays. by the solution and removal of the calcium carbonate. It is used in the manufacture of common brick. Outside of the moraine the shale also is deeply weathered, as is well shown in several railroad cuts between Hackettstown and Washington. At Port Murray (Loc. 282) it is utilized by the Natural Fireproofing Company in the manufacture of fireproofing (Plate LVI). Similar weathered material occurs abundantly in this vicinity and in the shale belt west of Clinton along the line of the Central R. R. of New Jersey. North of the moraine the shale is covered by the glacial drift, or if exposed, is in general but slightly weathered. The fresh shale, when ground up and mixed with water, is lacking in plasticity and tensile strength and, therefore, does not give such good results as that which has been deeply weathered. This being so, it is doubtful whether the great shale deposits within the glacial area will ever prove of value for these purposes. PRE-CAMBRIAN ROCKS. The pre-Cambrian rocks occur in the Highlands. They are chiefly gneisses, schists and granites. Some of the latter are coarse feldspathic rocks, although by far the greater part are not. Under favorable conditions the decay of a coarse-grained granite will give rise to a mass of kaolin, with some mica and quartz. Such deposits are known to occur in New Jersey, but they are of small extent and unworked at the present time. In the Annual Report for 1874 such a deposit is noted as occurring in a narrow valley one and one-half miles southwest of Bethlehem, Hunterdon county, on lands owned by Mr. Willever, and later by S. L. Shimer, of Phillipsburg. A shaft 33 feet deep is reported to have been sunk in it without reaching its bottom. The bed was a mixture of white clay, with a large percentage of very fine white quartz and partially decomposed feldspar. Analyses of the crude material show a large amount of potash, with some lime and magnesia and a little oxide of iron, the latter giving it a dark color in burning. A somewhat similar appearing deposit has also been observed near Amsterdam, Hunterdon county, on the property of Mr. Rapp. It lies in a little hollow, near the road from Amsterdam to the Delaware river. A small opening was made here some years ago, and a little clay shipped. An analysis of this clay is given in Chapter XIX, under the head of Hunterdon county. Within the region which was covered by the ice sheet of the last Glacial epoch, the surface of the Highlands was in general severely eroded and all residuary material removed. The rocks there, where outcropping on the surface, as well as where exposed beneath their covering of glacial drift, are generally hard and unweathered. Under these circumstances it is extremely doubtful whether any workable residuary kaolin deposits will ever be found in that area. 14 CL G |