Geology is that branch of natural science which treats of the structure of the crust of the earth and the mode of formation of its rocks, together with the history of physical changes and of life on our planet during the successive stages of its history. It depends upon mineralogy for its knowledge of the constituent rocks, and upon chemistry and physics for its knowledge of the laws of change; and in its study of fossil remains it is closely connected with the science of zoology and botany. A knowledge of geology lies at the base of physical geography, and is essential to the skillful prosecution of mining and other useful arts.

The geological history of the earth is ascertained by a study of the successive beds of rock which have been deposited on its surface, and of the masses which have been forced up in a liquid state from within its crust, together with the fossil remains of animals and plants which certain of the beds contain. As thus established, it is usually divided into four great periods, the names of which are taken from the progress of animal life, as this at present affords one of the best criteria for geological classification. They are: I., the Eozoic, or “period of the dawn of life”; II., the Paleozoic, or “period of ancient life”; III., the Mesozoic, or “middle period of life”; and IV., the Neozoic, or “recent period of life.”

Each of these admits of subdivisions, which may stand as follows, beginning with the oldest: Eozoic---Laurentian and Huronian; Paleozoic---Cambrian or Primodial, Siluro Cambrian, Silurian, Devonian, Carboniferous, and Permian; Mesozoic---Triassic, Jurassic, and Cretaceous; Neozoic---Eocene, Miocene, Pliocene, Post-pliocene, and Recent.

In the oldest condition of the earth, shown by the most ancient of the rock formations above referred to, its surface was covered with water more generally than at present, and sediments were then, as now, being deposited in the waters. The earth must, however, have an earlier history than this, though not represented by distinct geological monuments. This primitive condition of the earth is a subject of inference and speculation rather than of actual knowledge; still, we may begin with a consideration of a fact bearing upon questions which has long excited attention. It is the observed increase of temperature in descending into deep mines and in the water of deep artesian wells---an increase which may be stated in round numbers at one degree of heat of the centrigrade scale for every 100 feet of depth from the surface. These observations apply, of course, to a very considerable depth, and we have no certainty that this rate continues for any great distance toward the center of the earth. If, however, we regard it as indicating the actual law of increase of temperature it would result that the whole crust of the earth is a mere shell covering a molten mass of rocky matter. Thus a very slight exercise of imagination would carry us back to a time when this slender crust had not yet been formed, and the earth rolled through space an incandescent globe, with all its water and other vaporizable matters in a gaseous state. Astronomical calculation has, however, shown that the earth, in its relation to other heavenly bodies, obeys the laws of a riged (sic) ball, and not of a fluid globe. Hence it has been inferred that its actual crust is very thick, perhaps not less than 2,500 miles, and that its fluid portion must therefore be of smaller dimensions than has been inferred from the observed increase of temperature. Further, it seems to have been rendered probable, from the density of rock matter in the solid and liquid states, that a molten globe would solidify at the center as well as at the surface, and consequently that the earth must not only have a solid crust of great thickness, but also a solid nucleus, and that any liquid portions must be a sheet or detached masses intervening between these. Still this would merely go to show that the earth has advanced far toward the entire loss of its original heat. Other considerations, based on the form of the earth and the distribution of variances, lead to similar conclusions. It must be observed, however, that there are good reasons for the belief that the products of volcanoes, arise chiefly from the fusion of portions of the stratified crusts. Such considerations, however, lead to the conclusion that the former watery condition of our planet was not its first state, and that we must trace it back to a previous reign of fire. The reasons which can be adduced in support of this are no doubt somewhat vague, and may in their details be variously interpreted, but at present we have no other interpretation to give of that chaos, formless and void, that state in which “nor aught nor naught existed,” which the sacred writings and the traditions of ancient nations concur with modern science in indicating as the primitive state of the earth.

In the Eozoic time we have actual monuments to study. The Laurentian rocks, more especially, occupy a very wide space in the northern part of America. These rocks stretch along the north side of the St. Lawrence River from Labrador to Lake Superior, and thence northwardly to an unknown distance. In the Old World the rocks of this age do not appear so extensively, although they have been recognized in Norway and Sweden, in the Hebrides, and in Bohemia. Geologists long looked in vain for evidences of life in the Laurentian period, but its probable existence was inferred from such considerations as the abundance of carbon, limestone, iron, etc. --- materials known to be accumulated in the newer formations by the agency of life. In addition to the inferential evidence, however, one well-marked animal fossil has been found in the Laurentian of Canada---Eozoon Canadense, a gigantic representation of one of the lowest forms of animal life, that of the Protozoa, and type still extant in the ocean, and remarkable for its power of collecting and secreting calcareous matter.

The following pertaining to the geological structure of Jefferson County is condensed from Dr. Hough’s excellent chapter on that subject published in his History of Jefferson County, in 1854: ---

Geologists divide rocks into two great classes, primary and sedimentary or secondary; the first, from their crystalline character and mode of occurrence, often exhibit evidences of having been subjected to the agency of heat, while the latter appear made up of materials derived from the former, broken up and deposited in water, and usually contain fossil remains of animals and plants, that lived at the period of their formation. Both primary and secondary rocks occur in Jefferson County; the former of which, with the dividing line between them, affords only rational prospects of valuable metallic veins and deposits, as well as most of the crystalline minerals. Of the latter we are not without localities that vie with the most noted, and the primitive region of the county will abundantly repay the labor of mineral collection. The rock constituting the primary is mainly composed of gneiss; a mixture of quartz, feldspar, and mica, which are regarded as elementary or simple minerals, and make up by far the largest part of what is known of the earth’s surface. In gneiss these usually occur in irregular strata, often contorted, never horizontal, and seldom continuing of uniform thickness more than a few feet. It forms by far the largest part of the surface rock throughout the great northern forest of New York, embracing nearly the whole of Hamilton, and a part of Lewis, Herkimer, Fulton, Saratoga, Warren, Essex, Clinton, Franklin, and St. Lawrence counties, and in Jefferson this rock constitutes the greater part of the islands in the St. Lawrence, between French Creek and Morristown, and appears in Clayton, Orleans, and Alexandria on the river bank; in the latter town it extends back a mile or two from the shore. It forms a strip extending up both sides of Indian River to Theresa village, and the shores and islands of most of the lakes of that town and Antwerp, and much of the country within the node of Indian River, towards the village of Philadelphia, where it forms the surface rock and extends to Antwerp, the greater part of which it underlies. From this town it extends along Indian River to the village of Natural Bridge, and thence to Carthage, where it forms the islands among the rapids of the Long Falls, and thence follows up the river, keeping a little west of its channel, through Lewis and Oneida counties. In this area there are occasional ledges of white or primary limestone, especially in Antwerp, with limited quantities of serpentine, and superficial patches of sandstone.

Lying next above the primitive, and forming a considerable amount of surface rock, in Alexandria, Theresa, Clayton, Orleans, and Antwerp, is the Potsdam sandstone, so named from the fine manner in which it is developed in that town. It is the oldest of sedimentary rocks, and contains (but rarely) the forms of organic bodies that were created at the dawn of the vital principle. Two genera, one a plant, the other a shell, have been found in this rock, but so rarely that it may be almost said to be without fossils. Its principal constituent is silex, in the form of sand, firmly consolidated, and forming, where it can be cleaved into blocks of regular shape and uniform size, a most elegant and durable building material.

In the vicinity of Theresa, Redwood, etc., there occurs in numerous places in this rock the cylindrical structure, common at many localities in St. Lawrence County, and apparently produced by eddies acting upon the sands at the bottom of the shallow water. This information is generally in thick masses, often disturbed by upheavals, almost invariably inclined from the horizontal, and seldom in this county so evenly stratified as to admit of that uniformity of fracture that gives value to it as a building material at Potsdam, Malone, etc. It is, however, extensively used for this purpose, and forms a cheap and durable, but not an elegant, wall. This rock has two applications in the useful arts, of great importance--the lining of blast furnaces, and the manufacture of glass. The quarry that has been most used for lining stone is in Antwerp, where the rock occurs highly inclined, but capable of being divided into blocks of uniform texture and any desirable size. The edges of the stone, when laid in the furnace, are exposed to the fire, and become slightly fused, forming a glazing to the surface. For the manufacture of glass the stone is calcined in kilns and crushed and sifted, when it affords a sand of much whiteness, and eminently suitable for the purpose.

This rock is generally overlaid by a fertile soil, but this is more due to the accidental deposition of drift than the disintegration of the rock itself, for such is its permanence that it can scarcely be found to have yielded to the destructive agencies that have covered many other rocks with soil. The polished and scratched surfaces given by diluvial attrition are almost uniformly preserved, and wherever this formation appears at the surface it presents a hardness and sharpness of outline strongly indicative of its capacity to resist decay. A very peculiar feature is presented by the margin of this rock, which, by the practiced eye, may be detected at a distance, and which strongly distinguishes it from all others. The outline is generally an abrupt escarpment, sometimes extending with much regularity for miles, occasionally broken by broad, ragged ravines, or existing as outstanding insular masses, and always presenting, along the foot of the precipice, huge masses of rock that have fallen from above. The most remarkable terrace of this kind begins on the north shore of Black Lake, in Morristown, and extends through Hammond into Alexandria, much of the distance near the line of the Military road, and other instances are common throughout the region underlaid by this rock.

Next in the ascending series is a rock which, in this part of the state, constitutes a thin but level formation, and from its being a sandy limestone has been named a calciferous sandstone. This rock appears as the surface rock between Antwerp and Carthage; between the Checkered House, in Wilna, and Natural Bridge; between Antwerp and Sterlingville; and in Theresa, Alexandria, Orleans, and Clayton. In many places it is filled with fossils, and is valueless as a building material.

Next above this rock is the chazy limestone, that occurs highly developed, and abounding in organic remains, but, according to Professor Emmons, does not appear in the Black River valley. The next rock there is the Birds-Eye limestone, which includes the close-grained, hard, and thick-bedded strata, in which the layers of water limestone occur in Le Ray, Pamelia, Orleans, Brownville, and Clayton. Its color is usually bluish and light gray, weathering to an ashen gray; its fracture is more or less flinty, with many crystalline points; and its fossils few and seldom obtained except on the weathered surface. Its characteristic fossil, in the manner in which its verticle (sic) stems divide and interlace with each others, presents features totally distinct from any known analogy, either in marine plants or the zoophites. These stems are filled with crystalline matter and often make up a great part of its mass. When polished this rock presents an appearance which has given it the name, and in quarrying it readily breaks into regular masses. This forms the surface rock over a considerable extent of Cape Vincent, Lyme, Brownville, Pamelia, Le Ray, and Wilna. The part that overlies the yellowish water lime strata abounds in nodules of flint that everywhere stand in relief upon the weathered surface. These are thought to be the fossil remains of sponges, or other form of animal life, analogous. These masses of flint often contain shells, corals, crinoidea, and obscure traces of other organic bodies.

It is to be observed of the strata that intervene between the water lime (sic) and the Trenton limestone that form from their soluble nature the natural seams have generally been widened into open chasms, and that from this cause streams of water often find their way under ground in dry seasons. Although generally horizontal the strata are occasionally disturbed by upheavals, as is seen at several places along the line of the railroad between Chaumont and Cape Vincent.

The next rock above those described is named the Trenton limestone, which mostly constitutes the rock underlying the soil in Champion, Rutland, Watertown, Hounsfield, Henderson, Ellisburgh, Adams, and a part of Rodman and Brownville. In extent, thickness, number of fossil remains, and economical importance it far surpasses the others. It underlies extensive districts in the Western states, where it is recognized by its characteristic fossils. Its color is usually gray, and its fracture more or less crystallinie, occurring usually in strata nearly or quite horizontal, and of the separated by thin layers of shale. Many of its fossils are common with the slates above.

Fossil plants of the lower orders are somewhat common, but are limited to a few species. Of corals the number is greater; 20 different species of zoophites are found in this rock. Of that singular class of animals called trilobites, of which there are at present but few living analogies, the Trenton limestone furnishes several species. Of shells this rock affords a very great variety. Its stratification is generally nearly horizontal, and disturbances, when they occur, are usually quite limited. In some places it contains veins of calcite, and of heavy spar, the latter, in Adams, being associated with fluor-spar.

Resting upon the Trenton limestone, with which, in the bed of Sandy Creek, in Rodman, it is seen in contact, is a soft black slate, readily crumbling to fragments under the action of frost, and divided by verticle(sic) parallel seams into regular masses. From its appearance in the hills north of Utica it has been called Utica slate. It has not been found applicable to any useful purpose, although experiments have been made to test its value as a lithic paint. Where sulphuret of iron could be procured the manufacture of alum might be attempted with prospect of success. Fossils are common, but less numerous in this rock than in those below it. Several of these are common in the rocks above and below this. Only one species of trilobite is found, though they occur both above and below it.

Sulphur springs are of frequent occurrence in this rock, and native sulphur is sometimes noticed incrusting the surfaces in ravines, where waters, charged with sulphuretted hydrogen, have been exposed to vegetable action.

Covering this formation, and constituting the superficial rock of Lorraine, Worth, and a part of Rodman, is a series consisting of alternating layers of shale and slate, some of which are highly fossiliferous and others entirely destitute of organic remains. From the remarkable development of this rock in Lorraine it has received the name of Lorraine shales. For a similar reason it is known elsewhere as the Hudson River group, from its forming the highly inclined shales that occur, of enormous thickness, in the valley of the Hudson. This rock is nearly worthless for any useful purpose, although at Pulaski and elsewhere layers are found that are adapted for building. The mineral springs of Saratoga arise from this rock. Having thus briefly enumerated the leading geological features of the county some generalizations of the several rocky formations may be made.

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