Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/487

Rh STATE.] NEW Y. R K 453 spread over its deep water deposits mixed sediments, the finer wash of the land and organic material, carbonaceous or calcareous. When indurated, these three kinds of de posits became (1) sandstones or conglomerates, (2) lime stones, (3) shales or earthy limestones. During the inter vals of emergence the surface was more or less eroded, and the elevations gave obliquity to the planes of deposition, so that in each invasion of the sea it deposited its round of sediments unconformably upon the older ones. The repeated submergences which have here left their record did not cover the same area, but overlapped in such a way that the succession of deposits is easily made out, the different groups which we call geological systems being separable by unconformability along the planes of contact, by lithological characters which are faithful records of conditions of deposition, and by differences exhibited in their fossils, for in the long intervals which separated these inundations the life of sea and land was completely and repeatedly revolutionized. The processes described above went on through the Cambrian, Silurian, Devonian, and Carboniferous ages, forming on the south shore of the Laurentian continent the most complete and consecutive record of Palaeozoic time of which we have any knowledge. Then the strata along a line passing south-westerly through eastern New York were raised in a series of folds which we call the Alleghany Mountains, and at this time all the interval between the Atlantic and the Mississippi was elevated above the ocean. There it has since remained, the sea rising and falling upon its margin, and leaving its marks, but never sub merging the interior. The geological record was con tinued by minor contributions to the land along the Atlantic coast during the Triassic, Cretaceous, Tertiary, and Quaternary ages, and by the grinding and trans porting action of glaciers Avhich once covered the entire surface of the State. Previous to the elevation of the Alleghanies the sheets of Palaeozoic rocks formed a littoral plain sloping gently southward from the Archaean continent. But in the formation of this mountain belt the country traversed by the southern line of the State was left with a surface inclination northward, and between the Alleghanies and the Canadian and Adirondack highlands a broad valley was formed which became the channel of drainage for a great interior area. Through this valley flowed a large river which reached the sea at or near New York island. From the Carboniferous age to the Ice period this was the course of the drainage of the interior, and thus was formed the great water-gap between the Helderberg and Adiron dack Mountains, the gate of the continent, through which the tide of migration has flowed from the seaboard into the Mississippi valley, and where the canal and railroad lines have been constructed which are the great arteries of commerce. During portions of the Tertiary age perhaps the whole, but certainly the eastern margin, of the continent stood many hundred feet above its present level. The drainage of the interior flowed freely and rapidly through the channel which has been described, until that part of it which lies within the State was cut below the present sea- level, and the great river, which as a whole has never been named, but of which the Hudson, the Niagara, the Detroit, and the St Mary s are representatives, reached the ocean 80 miles south and east of New York harbour, for its channel may be traced to that point on the sea bottom, and its mouth was 600 feet below its present one. By a subsequent depression of the land or rise in the ocean-level the sea covered much of its old shore, and filled the channels cut by subaerial erosion ; the Hudson became an arm of the sea, and the labyrinth of tideways was formed which are such a marked feature of the coast, and such important auxiliaries to New York harbour. During the Ice period important changes were made in the topography of the State, by local glaciers in its advent and decline, by the great ice sheet at its climax, the first perhaps increasing topographical variety, the second producing monotony by grinding down and round ing over asperities, and filling depressions with the debris. The basins of the great lakes which border New York, Ontario, Erie, and Champlain, and of the peculiar elongated lakes of the interior, are largely the work of glaciers, which broadened and perhaps deepened river channels, and dammed them up with moraines. When the glaciers retreated from the area of New York many of the old channels of drainage were left partially or com pletely filled, and the flow of surface water took in some cases new directions. Among the obstructed channels was that of the Hudson west of Albany, filled by the Ontario glacier. By this cause the great river flowing from the interior was deflected from its ancient course and found a line of lowest levels leading from the north-east instead of that from the south-east corner of the Ontario valley. In this way the St Lawrence was made the outlet of the interior basin, and the Mohawk dwindled to a local drain ing stream. Long Island Sound and part of Long Island itself should also be classed among the products of glacial action, the Sound having been scooped out by the great glacier when it left the more resistant ledges of crystalline rocks which occupy south-eastern New York and Con necticut, and plunged into the softer Cretaceous and Tertiary beds which formed the littoral plain that bordered the continent, the hills of the island being covered, and in part composed of loose material transported by the glacier and deposited along its edge. Minerals. The mineral resources of New York, though less varied than those of some other States, are still of great importance. The most valuable of these are exten sive deposits of iron ore, viz.: (1) magnetite, found in great abundance in the Adirondack region, and in Putnam, Orange, and Rockland counties ; (2) haematite, mined in the vicinity of Rossie (St Lawrence county), Clinton (Oneida county), and elsewhere ; (3) limonite, largely worked on Staten Island, and at Amenia, Sharon, &c., on the line of the New York and Harlem Railroad ; (4) siderite, mined at Hyde Park on the Hudson. The pro duction of ore from these mines in 1879 was 1,239,759 tons, valued at $3,499,132; and New York is surpassed in the quantity of iron produced by Michigan and Pennsyl vania only. The quarries of New York are numerous, and they furnish a great variety of products : granite in the Adirondacks and along the Hudson ; roofing slate in Washington county ; white marble in Westchester and St Lawrence counties; red marble at Warwick, Orange county; black marble at Glenn s Falls ; verde antique at Moriah and Thurman. Sandstone comes from Potsdam, Medina, and various other localities ; shell-limestone from Lockport and Hudson ; excellent flagging from Kingston on the Hudson ; and paving stone from the trap of the Palisades. In 1880 the quarries of New York numbered two hundred and fifty-one, and the value of their product was $1,261,495. A large amount of hydraulic cement is supplied from the quarries at Rondout (Ulster county), Manlius (Onondaga county), and Akron near Buffalo ; also gypsum from the vicinity of Syracuse. The deposits of these substances are very extensive, and their production could be increased indefinitely. Another item of importance among the mineral resources of the State is the salt produced from the salt- wells at Syracuse; these have been worked for