THAT portion of New Jersey which is of the Triassic or Red Sand Stone Age, is included in a belt of country which has the Highland Range of mountains on its northwest side, and a line almost straight, from Staten Island Sound near Woodbridge, to Trenton, on its southeast. It has the northern boundary and the Hudson River on the northeast, and the Delaware on the southwest. The area within these bounds is entirely free from rocks of an earlier age, and also from any extensive formations of a later period. The strong and decided red color of the prevailing rock of this formation, has given name to the whole, and while most names of the kind have been discarded by geologists, this is so striking and suggestive that it receives the approval of all.

The precise age of this formation, it has been difficult to settle on account of its containing very fine organic remains. It is undoubtedly older than the cretaceous, for that overlies it at Woodbridge and Perth Amboy. It lies upon the magnesian limestone at various places along its northwestern border. The stems of plants are found fossil in this rock in the quarries at Newark, Belleville, or Franklin, and probably at many other places. The plants found evidently belong to orders higher than those of the Carboniferous Age. And the foot prints are those of air-breathing animals, probably of the Reptilian Age.

There is a renewed interest in the geology of this district, in connection with the issue of the first topographical map of New Jersey. This map was entitled a map of "a part of Northern New Jersey," and nearly all of the area which it represents is included in the red sandstone district. The red sandstone is represented not only in New Jersey, but also in New York, Connecticut, Massachusetts, Pennsylvania, Maryland, Virginia, and North Carolina, and it is marked by many characters, which are common to it, in all these States. Its brownish red color strikes the eye of every stranger who crosses it. And the well-known brownstone, so much used in building, is all obtained from this district.

Its geological age, structure and origin, have been the subjects of study by some of the ablest American geologists for nearly fifty years past, and many questions connected with it are still unanswered. Profs. William B. and Henry D. Rogers, in 1839, demonstrated that it was not as old as the coal formation, and Prof. Ed. Hitchcock, in the same year, with W. C. Redfield, presented strong evidence to show that it was older than the lowest member of the Jurassic formation. At a later period some evidence was brought forward by Lyell and others, to show that some of the upper portions of the red sandstone were of the Jurassic formation. The extreme scarcity of fossils found in this rock has hindered geologists from reaching settled conclusions in regard to its precise geological position and age. At the present time most geologists designate it the Triassic formation.

The structure of the formation is remarkable. Its strata in New Jersey generally dip towards the northwest, as do those in Pennsylvania, and those most westerly in Maryland, Virginia, and North Carolina. On the contrary, the red sandstone in Massachusetts, Connecticut, eastern Virginia, and northern North Carolina, all dip towards the southeast. There is very little curvature to the strata, or bending or folding in any way. Thus, in passing across the belt of this rock which lies in New Jersey, the geologist going from the southeast towards the northwest will find generally the strata dipping towards the northwest at angles of from 15° down to 5°, or less, but no strata dipping towards the southeast. Neither has the rock been fractured or much disturbed by any later changes. A very few faults have been found, but they are of only a few feet in extent. Taking these data for a basis of calculation, it would make the formation not less. than 25,000 feet in thickness. This peculiar structure and enormous thickness have given rise to much speculation and study as to its origin, or the source whence all this material was derived.

Its origin was attributed, by Prof. Rogers, to a broad stream or water channel extending from higher grounds in North Carolina, and descending in its course across Virginia, Maryland, Pennsylvania, New Jersey, and New York, to its outlet on the ocean. And this stream, in the course of time, brought down and deposited in its channel or trough, the materials in the position in which we now find them. The difficulty in accepting this explanation is, that the strata dip towards the northwest side of the stream, and not up or down it, as we should expect them to do. Various other explanations have been attempted, depending on changes of level due to the enormous weight of a mass of rock five miles thick upon a limited portion of the earth's surface; or to the internal changes effected by the rupture of the earth's crust and the escape of the great mass of eruptive rock which are now piled up in the numerous trap ridges of this district; but none of these fully meet the difficulties of the case.

Prof. W. C. Kerr, in his "Geology of North Carolina," 1875, p. 145, says

There is no way of accounting for the present position of these (Tri- assic) beds with their opposite and considerable dips, but by supposing an up-lift of the intervening tract, such, and so great, that if the movement were now reversed, it would carry this swell of nearly one hundred miles breadth, into a depression much below the present level of the troughs in which these remnant fringes lie, so that there has been an erosion not only of ten to twenty thousand feet of the broken arch of the Triassic beds over this area, but also of a considerable thickness of the underlying rocks on which they had been deposited.

Prof. Israel C. Russell, read a paper in May 1878, before the New York Academy of Sciences, "On the Physical History of the Triassic Formation in New Jersey and the Connecticut Valley," in which he said "that the facts which we have gathered as to the physical history of the Triassic beds of New Jersey and the Connecticut Valley, tend strongly to show that these two areas are the borders of one great estuary deposit, the central portion of which was slowly upheaved and then removed by denudation. That the detached areas of Triassic rocks occurring along the Atlantic border, from New England to North Carolina, seem fragments of one great estuary formation, now broken up and separated through the agency of upheaval and denudation."