First and Second Mountains. From Cook's Geology of the State, 1868. -Prominent in the Triassic district are the two long and parallel ranges of trap-rock, known in Essex County as the First and Second Mountains. The easternmost or outer ridge, we shall call, for convenience of description, the First Mountain, while the inner parallel range may be termed Second Mountain. The former, rising at Pluckamin in Somerset County, has an east-southeast trend, for seven miles, to the gorge through which passes Middle Brook. The continuous ridge runs thence on an east and northeast course to Millburn, in Essex County, a distance of sixteen miles, where the gap between the two ends of the disconnected range is about one and a half miles. From Millburn to Patterson, a distance of fifteen miles, its course is a little east of north. The whole length of this moun- tain from its rise at Pluckamin, to its terminus near Siccomac, is forty-eight miles, and its general trend is north-northeast.

The prominent and characteristic feature of this mountain is the great difference between its inner and outer slopes. That towards the Second Mountain is gentle, while that towards the red sandstone country is steep, and in many places precipitous. The former corresponds to the dip of the shale or sandstone which forms the basis upon which the trap rests, and at nearly all points, trap constitutes the rock of this declivity. The steep outer slope shows sandstone or shale at the base, and up to the precipitous bluffs of trap, covered however, in places, by the debris from the rocks above. The breadth of this range is quite uniform, from one to two miles. The height is also remarkably uniform, ranging from three hundred to six hundred and fifty feet above the level of the sea.

Everywhere the trap forms the crest and upper portion of this slope, under which is the sandstone, generally covered by trap debris. The top of the sandstone is from one hundred to one hundred and fifty feet below the top of the mountain. The located line marks the base of this steep face, and is at the same distance from the top of the mountain. It is plain on all the roads crossing the ridge, e. g., on the old South Orange Turnpike, the mountain road, Mount Pleasant Turnpike, near the Llewellyn S. Haskell place, also in the Park, in West Orange Township.

The western boundary line of the trap of the First Mountain follows the general direction of the valley included between the First and Second Mountains. The drift here, also, renders the tracing of a geological line quite difficult. But from the known uniformity of the trap slope, and an examination of the surface configuration of the county, and a few points of outcrop, the line can be quite accurately fixed and described. Generally it follows the line of least elevation, or at the bottom of the valley, and this in most cases at the foot of the First Mountain slope. Beginning at the northern end of this range, the Oldham Creek is coincident with a line almost to the pond north of Haledon ; thence, running east of this village, and on the same side of the creek, it meets the Passaic River west of the mouth of Oldham Creek, and follows the river for a mile to the Morris and Essex Canal, which constitutes the west boundary of this range to the Little Falls and Notch Road. The trap appears at several points along the river from the mouth of the creek to the bend in the former, where the line leaves it. East of this, the First Mountain is made up of several rocky ridges, separated by narrow valleys.

From the Notch Road southward, the trap boundary follows the same general direction as the mountains; crosses the county line, the crest forming the boundary line between Caldwell and Montclair townships, to the east of Verona Village, to the water shed of the Verona Valley, near the upper side of Llewellyn Park, west of Eagle Rock ; thence down the valley of the west branch of Rahway River as far as the old South Orange Road. Approaching the stream, it at length crosses it, and intersects the Morris and Essex branch of the D. L. & W. R. R., about three quarters of a mile west of Millburn Village. Along the line just mentioned, drift knolls and beds rest upon the lower portions of the trap slope ; near the crest of the main and subordinate ridges the rock is frequently seen. Nearer Millburn the slope is less obscured by drift, although west and southwest of the village, it hides all rocks.

In the east face of the Watchung or Orange Mountains, (as it is often called) in West Orange Township, trap-rock is quarried extensively for road material, by George Spottiswoode, John O'Rourke and General John G. Wright. These three quarries have each a cracker for breaking up the stone, and they supply a large amount annually for the construction of Telford roads in all the Oranges, Montclair, Bloomfield, and other localities.

Second Mountain. -As in the case of the First Mountain, the trap-rocks occupy the inner crest and inner slope of this range, while the shale and sandstone form the base on which they rest. The latter rocks occupy the gentler slope from the bottom of the valley to the base of the trap, which is from one hundred to two hundred feet below the top of the range. While the inclination of the sandstone slope is about 5°, that of the trap above it is about 20°, and in some places it is almost vertical, although there are not such mural walls here as the Palisades or in the First Mountain. This line of demarcation between the steep and gentle slopes almost invariably marks the respective limits of the two rocks.

The boundary line between them is therefore of the same general course as that of the mountain itself, and also parallel throughout with the First Mountain. The prolongation of the range, at each extremity beyond the ends of the outer range, makes this mountain longer than the other by five miles.

This mountain continues the same general course as the First, and runs close to the M. & E. branch of the D. L. & W. R. R., and crosses it near the Chatham and Millburn Road. The cuts on the Morris and Essex Railroad show some trap that is rarely seen elsewhere. West of Millburn this boundary is obscured by the hills of drift that here abound, and until the old South Orange Road is reached, there is nothing decisive to indicate its location. It crosses this road a little west of the Hollow Road, and thence on a northeast course passes west of Verona Village in Caldwell township, and crosses the Pompton Turnpike to Little Falls. So far the Second Mountain presents a great deal of uniformity-the trap crest and steep slope, and below the gentler descent to the valley. The latter is covered with earth, gravel and boulders to such an extent that the sandstone and shale can be seen at only a few points on the old South Orange Road, and at a couple of quarries out on the Centreville Road. At Verona the valley is quite broad, and the trap outcrop is half a mile west of the village.