« EelmineJätka »
scribes the method of occurrence of the iron very fully (he had twice visited the locality), and shows conclusively that the doubts that have been expressed in regard to the meteoric character of the iron were well founded, and that the iron is most certainly of terrestrial origin. The presence of the iron in the basalt is explained by the supposition that it has in part been brought up with the basalt, and in part formed subsequently in it by a process of deoxidation through organic matter. In support of the latter view, the writer mentions that with the native iron in the basalt, both at Aussuk and Ovifak, occurs a considerable amount of graphite.
It is interesting to note in this connection, though having nothing to do with meteorites, that Mr. G. W. Hawes has shown that native iron occurs in grains distinguishable under the microscope in the labradorite rock from the Washington River, in the White Mountains.
Of the meteorites which have been described during the past year, several deserve especial mention. M. Daubrée has described a meteoric stone which fell at Feid-Chair, province of Constantine, Algiers. The fall was accompanied by a loud noise, and the stone struck with such violence as to bury itself in the earth to a depth of nearly one hundred feet. It proved to belong to the class of meteorites which contain but little iron, the mass being made up of gray doubly-refracting silicates-probably chrysolite and enstatite. The same author has also published an analysis of a new meteoric iron from Santa Catarina, Brazil. It is remarkable for containing a larger amount of nickel (34 per cent.) than any other iron which has been described. It exhibited fine Widmannstättean figures, contains niccoliferous magnetic pyrites and graphite, and is covered with a thin but firm crust of crystallized magnetite.
A most interesting meteorite fell on the 21st of December, 1876, at Rochester, Fulton County, Ind. The meteor, or bolide, of which it was a part was observed in many places in the West in its passage eastward over the states of Kansas, Missouri, Illinois, Indiana, and Ohio. In the words of Dr. Smith," the pyrotechnic display is said to have been transcendently beautiful, hardly equalled or surpassed by any previous occurrence of the kind.” It was described as a
fire-ball surpassing the moon in apparent magnitude, followed by a great number of smaller meteors. An observer in Columbus, O., stated that “the color of the light was yellowish-red, resembling the light from the red balls of fire thrown out by the explosion of some kinds of fire-rockets." Although the display occasioned by the passage of the meteor through the air was so brilliant, only a very small fragment seems to have reached the earth : this was found by Mr. Norris lying on the surface of the snow near where he had noticed it to fall. It weighed about three fourths of a pound. The description of the stone as given by Professor Shepard and Dr. Smith shows it to be remarkable for its coarse pisolitic structure, resembling, according to the latter, the meteorite of Aussun, France.
Two other meteorites have been described by Dr. Smith as having fallen within a month of the one which has just been mentioned. These are the meteorites of Warrenton, Mo., and of Cynthiana, Ky. The former fell about sunrise on the 3d of January, 1877. In its passage through the air it produced a noise similar to the whistle of a distant locomotive; and in falling struck a tree, breaking off some of the limbs. When it reached the ground it was broken into a number of pieces, which were picked up while still warm. Some ten or fifteen pounds have been preserved. The stone has a uniform dark ash color, and is soft and easily crushed, which accounts for its being so much fractured in falling.
The bolide of which the Cynthiana meteorite was a part was seen brilliantly over portions of Indiana and Kentucky. The fall was accompanied with considerable noise, producing much consternation among the inhabitants of the surrounding country. The stone was seen to strike the earth, and was immediately dug up from a depth of thirteen inches, to which it had buried itself. Its weight was about fourteen pounds. In character it much resembled the well-known meteorite of Parnallee, India.
Dr. Smith has also published accounts of the Waconda, Ks., meteoric stone discovered in 1876, but the date of whose fall is not known; also of the Bates County, Mo., meteoric iron (1875), and that of Rockingham County, N. C., discovered in 1863.
By T. STERRY HUNT, LL.D., F.R.S.,
GEOLOGY OF NEWFOUNDLAND. The progress of geological investigation in North America may be conveniently introduced by considering some of the results of the labors of Mr. Alexander Murray in Newfoundland, which is geologically as well as geographically a continuation of the Atlantic belt of continental North America. Mr. Murray's geological map of the island, published within the last year, together with his annual reports, and some recent notes of Mr. Milne, edited by Murray, give the following facts not generally known.
Besides the considerable areas of Laurentian gneiss long since recognized, accompanied in some places by the characteristic crystalline limestones, are areas of Norian or labradorite rocks. In addition to these, there is met with a great series, which, holding a position between the Laurentian and the Cambrian rocks, was by Murray designated as the Intermediate series, and regarded by him as equivalent to the Huronian, which he had formerly studied on the shores of lakes Huron and Superior. These rocks are most widely developed in Newfoundland in the peninsula of Avalon, and are principally crystalline schists with quartzites and conglomerates, including what have been called cherty and jaspery beds. These latter, in some instances at least, the writer has found to be petrosilex rocks, like those of the continental portion of the Atlantic belt noticed in the report of last year (page xcvi). This Huronian or Intermediate series has been described by Murray as carrying in Newfoundland organic forms-Arenicolites, and a patella-like shell (Aspidella). These are, however, found in beds referred to the summit of the series, and perhaps belong to the overlying Lower Cambrian strata, which rest upon the crystalline rocks in patches of varying extent, and consist of sandstones, conglomerates, and roofing-slates, passing upwards, without any visible break, into the so-called Lower Potsdam beds. These are fossiliferous slates and conglomerates, to which a thickness of 5400 feet is ascribed. Above them are other fossiliferous strata, assigned to the Calciferous sand-rock, to which succeeds a great mass of graptolitic slates referred to the Levis division of the so-called Quebec group, and containing the forms of the Arenig or Skiddaw of Great Britain. The fossiliferous strata of the Quebec group in Newfoundland are arranged in sharp folds running in a northeast direction, and are affected by great dislocations having a similar course. At the summit appears a great inass of what are described as igneous and magnesian rocks, composed of chloritic and hornblendic schists, with serpentines, which, according to Murray, seem “to be lapped over the inferior strata unconformably, and to come in contact with different members in different places.” This crystalline series is identical with what had previously been described by the geological survey of Canada, both in the province of Quebec and in Newfoundland, as a part of the Quebec group in an altered state; the conformable succession being, in ascending order, according to Logan, Levis, Lauzon, and Sillery, so that these crystalline rocks were conceived to be the Lauzon and the Sillery in a metamorphosed condition. With this the observations of Murray are in contradiction. The Sillery which, in accordance with the views of Logan, should overlie conformably the magnesian series, or, rather, form its upper part, is found by Murray to overlie with perfect regularity the fossiliferous strata; but, in every case where a contact has been seen, the Sillery passes unconformably beneath the crystalline magnesian rocks. These, then, according to Murray, are not altered strata of the Quebec group, but a newer series resting in discordance upon it, eruptive in their origin, and intermediate in age between the time of the Quebec group and the Loraine shales. In fact, these crystalline strata are found unconformably overlaid by fossiliferous strata belonging to the Loraine and Clinton periods. The succeeding Niagara formation is represented at White Bay by 2800 feet of conglomerates and slates with limestones, and the Devonian by about 3700 feet of sandstones and slates with plant-remains. The Carboniferous, which is found in southwestern Newfoundland, has in one place a thickness of
over 6000 feet, and resembles closely that of Nova Scotia, including limestones and gypsums. The largest coal-seam found has a thickness of three and a half feet. The Carboniferous rocks rest upon the Laurentian and upon the Potsdam.
These crystalline rocks, which overlie unconformably the uncrystalline Levis and Sillery beds, and are in their turn overlaid unconformably by the uncrystalline Loraine shales, are described in more detail as consisting, besides the rocks already mentioned, of greenish feldspathic and hornblendic rocks, serpentines, diallages, argillites, talcose and chloritic schists, and rusty-weathering dolomites. They include the great copper-mines of Tilt Cove and Terra Nova, and are identical with the crystalline Huronian rocks of the Atlantic belt. Reference to the Record for 1876 (page xcviii) will show the evidence there adduced in favor of the view that the Sillery is really a lower division than the Levis; that the unaltered Quebec group, as hitherto described, is an inverted series, the normal position of the Sillery being below, and not above, the fossiliferous Levis division; and, finally, that the so-called altered Quebec group is an older crystalline series. It is pretty evident to those who have studied critically the Atlantic belt that the apparent uncomformable superposition of these crystalline rocks to the Sillery and Levis in Newfoundland is nothing more than the phenomenon-so often seen along this belt-of the older rocks overriding an overturned fold of the fossiliferous strata. It may be added, in this connection, that the work of the geological survey of Canada during the past year in the province of Quebec has shown the truth of the view so long maintained by the writer, that the crystalline schists of the Green Mountain belt are, in their normal position, found unconformably beneath the fossiliferous strata of the Quebec group. The relations sustained by them in Newfoundland to the Cambrian rocks, on the one hand, and the Siluro-Cambrian, on the other, can only be explained by admitting a period of disturbance, accompanied by folding, subsequent to the Chazy period and previous to the Loraine. This doubtless corresponds to the great continental movement, which, as we know, immediately preceded the deposition of the Trenton limestone in the St. Lawrence valley.
Milne, who has studied with Murray some of these points in the geology of Newfoundland, adopts the notion that the