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8. It is not alone through a study of the crystalline rocks that the chemistry of the primeval world is interpreted. By a comparison of the kind and amount of salts dissolved in the waters of the primeval ocean that are enclosed in paleozoic strata with the kind and amount of salts dissolved in the waters of the present ocean, Dr. Hunt has shown that from the earliest geologic time until the present, alkaline carbonates derived from the subaërial decomposition of feldspar have been carried into the ocean by streams, and the calcium and magnesium in the ocean have been succ
ccessively precipitated as carbonates, producing limestones and dolomites, while common salt and calcium sulphate have accumulated in the present ocean, the former in large excess. There is abundant evidence that this palæozoic ocean was hotter than the existing one, as well as more saline, while it is equally evident that during long intervals its sediments carried down vast quantities of the remains of vegetable and animal life. He has further repeatedly shown in what manner these sediments were influenced by the organic matters that were enclosed in them.
In his essay on Chemistry of Natural Waters," he has shown that argillaceous sediments deprive waters of the organic matter in solution by forming a compound containing an organic radical. He says, “ There is reason to believe that alumina is under certain conditions dissolved by waters holding organic acids,” and cites melite and pigotite as examples of the compounds formed. He further shows that organic matter in water reduces sulphates to sulphides, producing from soluble sulphates of lime and magnesia carbonates of the basis, with hydrogen sulphide, free sulphur, or a metallic sulphide; the hydrogen sulphide being converted by slow oxidation or combustion, followed by absorption of oxygen directly into sulphuric acid, which is again, when in contact with organic matter, reduced to hydrogen sulphide. He
says with reference to the water of palæozoic brine springs, “In the large amount of magnesium chloride which they contain, these waters resemble the bittern or mother-liquor which remains after the greater part of the sodium chloride has been removed from sea-water by evaporation. .... The complete absence of sulphates from many of the waters points to the separation of large quantities of earthy sulphates in the Cambrian strata from which these saline springs issue ; and the presence in many of the dolomite beds of the Calciferous sand rock of small masses of gypsum,
abundantly disseminated, is an evidence of the elimination of sulphates by evaporation. .... . The brines of the valley of the Allegheny river, obtained from borings in the coal formation, are remarkable for containing large proportions of chlorides of calcium and magnesium, though the sum of these, according to the examples given by Lenny, is never equal to more than about one-fourth of the chloride of sodium. The presence of the sulphates of barium and strontium in these brines, and the consequent absence of soluble sulphates, is, according to Lenny, a constant characteristic in this region over an area of 2000 square miles.''l
Among many other illustrations that might be given of these non-sulphated paleozoic waters, I mention one which was obtained from a boring on Great Manitoulin island in Lake Huron, at a depth of 192 feet, “After passing through the black slates of the Utica formation, and for sixty feet into the underlying Trenton limestone. . . It contained no sulphates nor barium nor strontium." Another palæozoic water of a very different character was obtained from a well bored for petroleum at Bothwell, Ontario, in 1865. “At a depth of 475 feet from the surface, and probably at or near the base of the Corniferous limestone, a copious spring was met with of very sulphurous water and a little petroleum.' The water contained sulphate of calcium and sulphides of sodium and hydrogen. Waters apparently similar are pumped from several of the oil wells in the vicinity. “The sulphurous impregnation is doubtless to be ascribed to the reducing action of hydrocarbonaceous matter upon the sulphates which the waters contain."2
9. A brief examination of the superposition of the palæozoic and earlier formations of North America will show the Laurentian, embracing the oldest known rocks of the globe, outcropping from the coasts of Labrador to Lake Superior and over a large area in northern New York. Associated with this system is the Norian, which is characterized by a great development of opalescent feldspars. Above these are the Green Mountain series, an inferior part of the Lower Silurian, which corresponds wholly or in part to the Huronian system of Canada and the region about Lake Superior. Above them are the White Mountain series, which are Upper Silurian and perhaps Devonian. These formations constitute for the most
1 Bischof, Chem, and Phys. Geol., i, 337. Hunt, Chem, and Geol. Essays, P. 121, ed. 1875. Am. Jour. Sci., March, July and Sept., 1865.
? Essays, 158-163, ed. 1875.
part the rocks of Canada, New England, eastern New York and the eastern slope of the Alleghenies southward through New Jersey, Pennsylvania and Virginia. Speaking of these rocks, Dr. Hunt says, “In the oldest known of them, the Laurentian system, great limestone formations are interstratified with gneisses, quartzites and even with conglomerates. All analogy, moreover, leads us to conclude that, even at this early period, life existed at the surface of the planet. Great accumulations of iron oxide, beds of metallic sulphides and of graphite, exist in these oldest strata, and we know of no other agency than that of organic matter capable of generating these products. . . . . Bischof had already arrived at the conclusion, which in the present state of our knowledge seems inevitable, 'that all the carbon yet known to occur in a free state can only be regarded as a product of the decomposition of carbonic acid, and as derived from the vegetable kingdom.' He further adds, living plants, decomposed carbonic acid, dead organic matters, decomposed sulphates, so that, like carbon, sulphur, appears to owe its existence in the free state to the organic kingdom.' As a decomposition (deoxidation) of sulphates is necessary to the production of metallic sulphides, the presence of the latter, not less than of free sulphur and free carbon, depends on organic bodies; the part which they play in reducing and rendering soluble the peroxide of iron, and in the production of iron ores, is, moreover, well known.” 2
Rocks of the Lower Cambrian in Great Britain as well as in North America are well known to exhibit carbonaceous remains. Of the former it is said, “They occasionally hold flakes of anthracite, and small portions of mineral pitch exude from them in some localities:" The rocks of the Malvern hills contain fucoids. In the Quebec series on the south shore of the St. Lawrence, Hunt describes the occurrence of a carbonaceous substance, “entirely distinct from coal, which occurs in fissures, sometimes in the interstices of crystalline quartz. It is an insoluble hydrocarbonaceous body, bril- . liant, very fragile, giving a black powder, and results apparently from the alteration of a once liquid bitumen.”'3 Similar material
1 On the north sho of Lake Superior, I have found spherical concretions of graphite occuring in a rock that is apparently eruptive.
2 Essays, pp. 301, 302. Am. Four. Sci., 1871.
3 Essays, pp. 382, 396. W. Hodgson Ellis, “ Analysis of Some Precarboniferous Coals,” Chem. News, lxxvi, 186, Oct. 15, 1897.
often lines cavities in the limestone in Herkimer county, New York, and not only sometimes encloses crystals of quartz, but is often enclosed in quartz crystals. These limestones are not crystalline.
Above these formations just mentioned, in the Carboniferous formation of both Europe and North America, anthracite occurs in metamorphosed strata. In Wales, Belgium, the Alps and France, such phenomena are frequent. The coal deposits of Massachusetts and Rhode Island are enclosed in highly metamorphosed strata. Much of the material is more nearly graphite than coal. Both the coal and the enclosing strata are so distorted that the bedding is destroyed and the material appears in segregated masses.
In the trap dykes that have penetrated the sedimentary formations of the Connecticut valley and New Jersey, veins of carbonaceous matter occur. These dykes are intruded masses, no doubt formed by the igneo-aqueous fusion of sediments that contained organic remains. 1
10. With the exception of the exudation of mineral pitch mentioned above, I have seen no notice that bitumen occurs in crystalline rocks, but always in rocks adjacent to or above them. There are vast areas of the palæozoic formations of North America that are not crystalline, that have been more or less subjected to the action of steam and pressure at temperatures that have made them more or less the subjects of metamorphic action. Some of these rocks contain bitumen and others do not. The limestones in the bluffs of the Mississippi river at Minneapolis and St. Paul contain in the cavities of their fossils crystals of pyrite and rhomb spar. They immediately overlie the St. Peter sandstone and are said to belong to the Trenton group. Similar limestones in southern Michigan contain bitumen, free sulphur and sulphates in large amount. In southern Kentucky and Tennessee the limestones are often coarsely crystalline and contain large encrinite stems that are silicified. These same rocks contain geodes lined with crystals of quartz. Other geodes contain sulphates of barium, strontium and calcium, both with and without bitumen. In other localities the rocks of this age are filled with bitumen widely disseminated in small quantities. These rocks often exhibit very slight evidence of the effects of heat, but frequently are found immediately above or upon crystalline schists. ?
1 L. C. Beck, Am. Jour. Sci. (1), xlv, 335. I. C. Russell, ibid. (3), xvi, 112.
2 S. F. Peckham, Reports of the Tenth Census of the United States, Vol. x, “ Petroleum," p. 63.
11. In Prof. James Hall's celebrated Introduction to The Palaontology of New York, he shows that the earliest palæozoic sediments were deposited in a current that moved from southeast to northwest. Later the current moved diagonally across them from northeast to southwest. These later currents represent a vast interval of time, during which material accumulated to a depth of tens of thousands of feet of coarse sediments to the northeast in Canada, and growing finer diminished to the southwest in the Mississippi valley to a few thousands of feet. If metamorphic action is due to the accumulation of sediments, whereby the isothermal lines of the earth's crust rise to meet the increased pressure, by consequence of which sediments are brought into a state of igneo-aqueous fusion, it not difficult to explain why, at a period in the earth's history, when the condition of the earth's crust, the ocean and the atmosphere, all contributed to maintain a high temperature, the strata as we pass from the southwest in the Mississippi valley towards the northeast should present, at the surface, increasingly the effects of heat."
12. Let us now turn to Technology and see what the experience of more than half a century can teach us in relation to this question of the origin of Bitumen. Soon after 1830, Reichenbach in Germany, Sèlligue in France and Gregory in Scotland, all worked upon the destructive distillation of pyroschists, wood, coal, peat and petroleum. They all discovered paraffine, and what is suggestive, they all propounded the idea that bitumens are distillates. They established the fact that pyroschists, wood, coal, etc., when destructively distilled yield paraffine and the oils found in petroleum. Sélligue established quite a valuable industry in France, using as his raw material the schists of Autun. About 1850, the Scotch paraffine-oil industry arose. The raw material was a shale, called Boghead mineral, that was well known to contain fossil fishes. The distillate of this mineral closely resembled petroleum, and when petroleum was discovered in the United States in commercial quantities, the refineries on the Atlantic coast, that had been importing the Boghead mineral, commenced to work petroleum with slight changes in their processes. At the same time, the
1 Nat. Hist. of N.Y., “ Paläontology,” iii, 45–60.
Jour. für Chem. u. Phys., von Schweiger-Seidel, 1830, lix, 436. Trans. Roy. Soc. of Edinb., xii, 124. Rep. of Pat. Inven., n. s., iv, 109. Jour, des Connaisances Usuelle, Dec., 1834, p. 285. Dingler, lvi, 40.