but the indications were that it came from the excavation. In studying a series of slides, however, from the material received five years ago from Dr. Williams, one slide contained a crystal of brown hornblende like the above, and another had in the midst of the porphyritic peridotite, a chance inclusion about 10mm across which consisted of microperthitic orthoclase, in largest part, with some plagioclase, brown hornblende and titaniferous. magnetite. It is undoubtedly a fragment of the underlying Archæan crystallines, picked up by the intrusive peridotite, for its edges are sharp and all the associations are of this character. Mr. Darton also gathered specimens with undoubted inclusions of sedimentary rock. One of these is an argillaceous sandstone formed of quartz grains and interstitial clay; and the others are earthy limestones showing, under the microscope, sections of small brachiopod shells. No appreciable evidence of contact metamorphism could be detected.

It is interesting to note the thickness of sedimentary strata through which this dike must have come from its source in or

below the old crystallines. F. E. Englehardt* gives as the result of the State well at Syracuse, 1969 feet from the surface Salina to and 154 feet into gray Medina sandstone. Forty miles due west, at Clyde,† a well, begun in the Salina, went 1792 feet and stopped, being then 92 feet into the Hudson River shales. A few miles north of Clyde, a well at Walcott penetrated from the Niagara on the surface 2700 feet, and stopped 750 feet into, but not through the Trenton. While at Rochester,+ beginning in the Niagara, a well was put down 3078 feet, ending in white ferruginous quartz, supposed to be Archæan. Ashburner's generalized section along the meridian of Clyde, gives 4800 feet from the Helderberg to the Archæan, and the dike must have come up through some such section as this, until it stopped in the Salina strata.

NOTE: The following igneous intrusions have now been determined microscopically in central New York. At Syracuse, peridotite, G. H. Williams, this Journal, Aug., 1887, p. 37, Bull. Geol. Soc. Amer., I, 533; at Ithaca, 75 miles south of Syracuse, presumably peridotite, like preceding, J. F. Kemp, Idem., Nov., 1891, p. 410. The analysis given in this paper, as regards A120, and MgO is undoubtedly untrustworthy. At Manheim, 75 miles east of Syracuse, alnoite, C. H. Smyth, Jr., Idem. Apr., 1892, 322, Aug., 1893, 104. At Dewitt, 3 miles east of Syracuse, as above. In addition, boulders of a most interesting rock have been found at Aurora, N. Y., about 25 miles north of Ithaca, which consisted of great crystals of pyroxene and hornblende in a glassy ground-mass, and with no certain olivine. (J. F. Kemp, Trans. N. Y. Acad. Sci., XI, 126, 1892.) Boulders of the same rock with attached, fossiliferous Trenton limestone, have been found by J. M. Clarke, on Canandaigua lake, 30 miles west of Aurora, and have been described by B. K. Emerson. (12th Ann. Rep., N. Y. State Geologist, 1892, published 1893.) We may expect other dikes of these curious basic rocks to be discovered in the New York Palæozoic series, as time goes by.

* N. Y. Assembly Doc., 1885, No. 32, p. 15. Quoted by Ashburner in Trans. Amer. Inst. Min. Eng., XVI, 944.

+ C. S. Prosser, Amer. Geol., Oct., 1890, 203-204.

by Ashburner, loc. cit.

The same figures are given

H. L. Fairchild, Proc., Rochester Acad. Sci. I, 184, 1891.

ART. XL.-Note on the amount of Elevation which has taken place along the Rocky Mountain Range in British America since the close of the Cretaceous period; by DR. G. M. DAWSON. (Reply of March 18 to a letter from J. D. Dana.)

BETWEEN latitudes 49° and 52° (or thereabouts) numerous infolds of Cretaceous rocks occur in the Rocky Mountains. proper, or Eastern range of the Cordillera. (Laramide Range.) These consist chiefly of earlier Cretaceous (Kootanie) but in places strata as high up as Lower Laramie (St. Mary River beds) still remain. The actual elevation of these rocks is now in many places from 6000 to 8000 feet above sea-level. In the adjacent belt of foothills, to the east, the same Cretaceous rocks are found, but here still including strata as high as Upper Laramie. The actual elevation is here often between 5000 and 6000 feet above sea-level.

In the mountains, the Cretaceous rocks have been involved in all the flexure, faulting and overthrust suffered by the Palæozoic; and both in the mountains and foothills these rocks are found at all angles up to vertical and even overturned.

It is thus difficult to know to what elevations these rocks may have been thrust up in some places, but a minimum estimate may be arrived at by tracing the continuations of the beds over the less disturbed anticlinals or by adding their volume to the elevation of flat-lying ranges of the older rocks. About latitude 50° it may thus be shown that the base of the Cretaceous must in several places have considerably exceeded 10,000 in altitude, while in Mr. McConnell's section along Bow Pass (51° 15') to the north of Devil's Lake, the same horizon must have been about 15,500 feet above sea-level, the beds at this place being nearly flat.

To ascertain the uplift of the beds which were at sea-level at the close of the Cretaceous, the volume of the Cretaceous strata must of course be added to such figures as the above. This was, in the eastern part of the mountains, at least 17,000 feet and may well have been 20,000 feet (See G. S. C. Report, 1885, p. 166 B), giving as a minimum estimate of greatest uplift for the region say 32,000 to 35,000 feet.

Farther north, Cretaceous infolds in the Rocky Mountains become less common, so far as known, but the foothills retain the same general character to Peace River and beyond. Probably the uplift was somewhat less in these latitudes, as the Rocky Mountain range proper is less important and narrower. Still farther north, opposite the Mackenzie delta, Mr. McConnell describes the range as composed in its highest part

AM. JOUR. SCI.-THIRD SERIES, VOL. XLIX, No. 294.-JUNE, 1895.

sea.

of Cretaceous rocks, but there only about 4000 feet above the Several thousand feet have doubtless been removed by denudation, but we have no exact knowledge of the thickness of the Cretaceous in that region.

There are also some evidences of slight or moderate uplift in the Rocky Mountains proper of Alberta previous to or during the Laramie, such as the supply of material from the red rocks of the Triassic to the middle zone of the Laramie, opposite that part of the range in which these rocks occur, (see G. S. C. Report, 1882-84, p. 113 C.) as well as in the materials of the older Cretaceous conglomerates, although these last may in part have been derived from elevations west of the Laramide Range.

It is probably impossible to ascertain exactly how long the main uplifting process continued or to what extent its effect was counteracted by concurrent denudation, but some facts may be cited in this connection.-No deposits referable to the Eocene, as distinct from the Laramie, have been found in the foothills or over the Great Plains of Western Canada. It is probable that none such exist, and it may therefore be assumed that free eastward drainage, without arrest, obtained during this period. In the Early Miocene (White River) we find evidence that strong rivers were carrying coarse gravels from the mountains out over the plains to a depression some 200 miles east of the present base of the mountains, forming there a deposit of which outliers, like that of the Cypress Hills, still remain. These deposits, in their relation to the Laramide Range, resemble the Upper Siwalik Conglomerates of India, and it is probable that at this time a range comparable to the Himalayas in height, bordered the Great Plains of Alberta on the west.

During the Eocene and Miocene, orographic uplift may have been continuous, but sometime long before the close of the Pliocene it came to an end. Evidence of this is found in the following circumstances.-The Oldman, Highwood, Bow and other rivers flowing from the mountains, occupy notably wider valleys where they cross the eastern foothill belt. In these valleys Cretaceous and Laramie rocks, arranged often in compressed and complicated folds, are cut sharply off on planes nearly corresponding with the slopes of the present streams and upon the basset edges of these rocks bowlder-clay and other glacial deposits are spread. Since the Glacial period, the streams have cut out narrow new trenches in the floors of these valleys. The main valleys are therefore not only pre-glacial, but also involve a long antecedent period of erosion, during which the conditions changed little if at all. Had orogenic movements continued in the Pliocene, the flexed Cretaceous beds of the foothills (intimately connected with the general folding of the mountains) must have participated in them, and

no such uniform cutting out of wide valleys would have been possible. It was no doubt at this time also that much of the denudation of the Great Plains to the eastward occurred. In the vicinity of the western end of the Cypress Hills the general surface of the plain is now about 2200 feet lower than the Miocene capping of these hills.

ART. XLI.-On Three New Analyses of Sodalite, from three new localities; by L. McI. LUQUER and G. J. VOLCKENING.

Sodalite from Hastings Co., Prov. Ontario, Canada. THE massive sodalite from this locality was collected by Mr. T. D. Ledyard of Toronto. It was found in the northern part of Hastings County, Prov. Ontario, about 180 miles N.E. of Toronto. According to Mr. Ledyard's statement the sodalite does not appear to be very plentiful, takes a beautiful polish and occurs in the Laurentian formation. He also states that he has secured the mining rights of all the land on which the mineral is known to occur. The specimen examined has a very distinct cleavage, vitreous luster, cobalt-blue color, hardness of 5 to 6, and a colorless streak. It loses color, fuses with intumescence to a colorless glass, giving a strong soda flame, and is soluble in hydrochloric acid with separation of gelatinous. silica. A thin section in parallel polarized light appeared of a pale blue color, and showed by a few cloudy patches traces of decomposition. Between crossed nicols it was perfectly isotropic.

The other known occurrences of sodalite in this country are: Litchfield, Me. (blue); Salem, Mass. (violet-blue); Beemerville, N. J. (colorless grains in elæolite syenite)*; Crazy Mountains, Mont.; Brome, Montreal and Beloeil, Canada+; and Ice River, a branch of the Beaver Foot River, near Kicking Horse Pass in the Rocky Mountains, B. C.

Prof. Harrington of McGill University, Montreal, is at present preparing a report on Ontario sodalite and other Canadian minerals.

Sodalite from the Ural Mountains, Asia.

The specimen examined from this locality was obtained from a mineral dealer in Ekatherinburg. It is massive, almost

* J. F. Kemp, Trans N. Y. Acad. Sci., vol. xi. p. 60.

B. J. Harrington, Trans. Roy. Soc. Canada, Sect. III, p. 81, 1886.