Page:The American Cyclopædia (1879) Volume XII.djvu/368

356 NEW YORK (STATE) containing vast beds of specular iron ore. These rocks are doubtfully of Laurentian age, but their relations to other formations have not been determined. The crystalline rocks of this entire area are regularly stratified, and were formed anterior to the Potsdam sand- stone, which lies against and upon their up- turned and eroded edges. The Highlands on the Hudson are of the same age as the Adiron- dacks, and also contain heavy beds of magne- tite. The gneissoid and mica slate formation, which comes into the state from the south and passes eastward of the Highlands, is of more recent age, and contains no magnetite. In New York the Potsdam sandstone succeeds the Laurentian, and appears in a broad, con- tinuous belt along the N. and N. W. slopes of the Adirondacks, and in interrupted outliers on the east, from Clinton to Saratoga co. Overlying the Potsdam, the calciferous sand- stone is coextensive with it in the north, and extends further S. The Taghkanic range, including shales, sandstones, and limestones, often more or less metamorphic, with beds of hematite, white and variegated marbles, roof- ing slate, &c., must be considered of the same age as the Potsdam and calciferous sandstones and Chazy limestone of Lake Champlain. The Trenton group, including Birdseye, Black riv- er, and Trenton limestones, occupies much of Jefferson co., and, continuing S. E. through Lewis and Oneida cos., is seen at Trenton falls and in the Mohawk valley ; thence eastward and northward it encircles at least two thirds of the great Laurentian district. The Utica slate and Hudson river group, extending from near Rondout, form a belt on both sides of the Hudson to the bend at Sandy Hill ; follow- ing the course of the Mohawk valley as far as Rome, it diverges N. W. through Lewis and Oswego cos. to Lake Ontario. The Shawan- gunk grit or conglomerate, containing lead and copper ores, extends from the Delaware river to Rondout, where it suddenly terminates, and is not again seen in situ, except in Oneida co., where it is known as the Oneida conglomerate. The gray sandstone of Oswego holds essentially the same position, and bowlders and pebbles of similar conglomerate have been there found upon the surface. Southward from the out- crop of the Hudson river group, the Medina sandstone and Clinton group come in; the thin edge of the latter, beginning in Schoharie co., trends westward, and extends on both sides of Oneida lake, and thence with the sandstone forms a broad belt along the S. shore of Lake Ontario. The beds of fossiliferous iron ore of the Clinton group are extensively worked in Oneida and Wayne cos., and extend as far W. as Monroe. The limestone of the Niagara group produces the falls of the Niagara and the great escarpment of Lewiston and Queenston, which, beginning as a terrace in Schoharie co., extends through the state and western Canada. Co- extensive with this formation are the water- lime and salt groups ; of small force in eastern New York, they expand in the central part of the state. The salt group is the source of all the productive brine springs and wells, and also of the gypsum. The waterlime group furnishes nearly all the hydraulic cement. Entering the state from the N. W. corner of New Jersey, and occupying the valley W. of the Shawangunk mountain, a series of strata of no great promi- nence reach the Hudson at Rondout, trend northward in a low terrace everywhere marked by a limestone crest, and extend into Albany co. Here thickening and expanding, they con- stitute the Helderberg formations, separated into upper and lower by the Oriskany sand- stone ; these, surmounted by the Hamilton rocks, form the Helderberg mountains. The Hamilton group enters the state from the south at Deer Park, approaches the Hudson at Kings- ton, and thence following the base of the Cats- kills turns westward, expanding to a width of several miles, and becoming a highly fossilifer- ous group. The higher beds furnish the flag- stones which are extensively quarried and sup- plied to all the seaboard cities and towns of the north. The thicker beds are known as the Hudson river blue stone. The Portage and Chemung groups, the former marked by dark shales and flaggy sandstones, the latter by olive shales and heavy-bedded sandstones, form a broad belt, entering the state from Pennsyl- vania on the Delaware river ; thence, skirting the base and forming a considerable portion of the lower part of the Catskill mountains, they sweep around them to the north and occupy the valleys between them. From the Chenango river west these formations cover almost the entire width of the two southern ranges of counties, and outcrop on Lake Erie from Eight- een-mile creek to the Pennsylvania line. The Catskill or old red sandstone formation enters the state on the south in several belts, trending N. E. The more westerly of these soon die out, but the three easterly ones continue into Greene co., and uniting form the Catskill moun- tains. These belts, which are synclinals, carry also outliers of the succeeding formation, the lowest sandstones of the carboniferous system, forming considerable areas on the higher sum- mits of the Catskills and further south. Be- yond these lower carboniferous beds the geolo- gical series in direct succession is not continued within the state of New York. The red sand- stone of the middle secondary, or trias, extends from N. E. New Jersey over a part of Rock- land co., terminating at the Palisades on the Hudson and at Haverstraw bay. The cretace- ous formation is known on Long Island. The more recent formations are the post-pliocene of the Champlain valley, and the glacial or water-worn drift which to a great extent over- spreads the older formations. The mineral springs of Saratoga and Ballston rise from a line of fault which brings the Hudson river slates against the calciferous sandstone and limestones above. The sulphur springs of Sharon, &c., rise from the upper part of the