摘要:

It is the purpose of this paper to give a detailed description together with a discussion of the mode of origin of a series of the Absaroka volcanic rocks. The area lies within the limits of the Ishawooa Sheet of the Absaroka Folio (No. 52) and the Valley Post Office, near the center of the region, is on the South Fork of the Shoshone River, about 43 miles southwest of Cody, Wyoming. The Ishawooa Sheet was originally mapped under the direction of Arnold Hague in 1893 and 1897 and the subdivisions of the volcanics which the writer used in mapping this region are essentially the same as those used by Hague and others throughout the Absaroka Mountains and Yellowstone National Park. These subdivisions are shown in the legend of the geologic map, Figure 1. The plan of this paper is to give first a description of the pyroclastic rocks together with a discussion of their mode of origin and to follow this with a similar treatment of the early basalt sheets.

ISSN:0002-8606    

DOI:10.1029/TR016i001p00274-2

年代:1935

数据来源: WILEY

摘要:

Last summer (1934) I found several pieces of a brownish‐red, brick‐like rock in an inter‐Glacial moraine deposit in Iceland. This find, it is believed, furnishes evidence for a Pleistocene thermal activity in that island.The present‐day thermal activity in Iceland is unequalled in intensity and extent. On the accompanying map (Fig. 1) all known localities of hot springs have been plotted, and in order to give a better idea of the proportions, the little square in which the legend of the map is printed has been drawn so as to represent the area of Yellowstone National Park on exactly the same scale. Since the intensity of the thermal activity is not less in Iceland than in Yellowstone, it is readily understood that the hot springs of Iceland are of great geologic importance. They are responsible for a large number of extensive deposits of chlorides, sulfates, and of native sulfur, as well as silica sinter, and last but not least, they have over large areas acted on the adjacent rocks and transformed them into clay‐like substances. A question immediately presenting itself to the geologist is therefore the antiquity of this impressive thermal activity. Can it be traced farther back than those thousand and some years constituting the written history of Iceland? We do know that the lifetime of the individual springs varies considerably. Several of the voluminous alkaline springs are at least 1000 years old, but several examples are also known of springs which came into existence and entirely disappeared in less than

ISSN:0002-8606    

DOI:10.1029/TR016i001p00284-2

年代:1935

数据来源: WILEY

摘要:

The study of the Highwood Mountains was undertaken by a group of men from Harvard University under a grant from the Shaler Memorial Fund of the Department of Geology. The work was under the general direction of Larsen, who, with the assistance of Norman A. Haskell, mapped most of the volcanic rocks. Hurlbut and Griggs worked mostly on the laccoliths, Burgess on the stocks, and Buie on the dikes. The party spent two summers in the field. The laboratory work is far from complete. We cooperated closely in all the work.

ISSN:0002-8606    

DOI:10.1029/TR016i001p00288

年代:1935

数据来源: WILEY

摘要:

The history of vulcanism in Alaska is a topic of great universal interest, but one which has had no adequate treatment. For some years the writer has been accumulating comparative data on this subject, and it is hoped that this information may some time be sufficiently amplified and coordinated to justify a general description of the sequential igneous history of Alaska. The scope of such an undertaking, however, can well be appreciated from the statement that Alaska is nearly a fifth the size of the United States, and that geologic studies have shown that igneous rocks have originated in Alaska in every geologic period, excepting perhaps the Cambrian and the Silurian. Therefore, in the present paper, it has seemed best to present only a part of this interesting record, and perhaps in subsequent papers to expand the areal and geologic limits of discussion.

ISSN:0002-8606    

DOI:10.1029/TR016i001p00292

年代:1935

数据来源: WILEY

摘要:

In the course of the study of the deposits of magnesite and brucite in the Paradise Range by the Geological Survey In cooperation with the Nevada state Bureau of Mines, opportunity was afforded to map a part of a granodiorite stock and a swarm of dikes. Seven successive igneous intrusions, demonstrated by cross‐cutting relationships, occur in this area of a little more than a square mile. Three distinct kinds of dike rock, andesite hornfels, andesite, and granophyre. are earlier than the granodiorite, and three kinds, malchite, mafic malchite, and rhyolite, are later than the granodiorite. In the succession of intrusives the silica‐content rises to a peak in the granophyre and falls to a low point in the mafic malchite. The youngest dike, rhyolite, is probably not related magmatically to the others. Perhaps the most interesting feature is the preservation of large parts of the andesite dikes within the granodiorite body, implying the removal by the granodiorite of the carbonate rock which the andesite originally intruded. This feature recalls Barker's description of the marscoite sills of Skye (Alfred Harker, The Tertiary Igneous rocks of Skye, Mem. Geol. Surv., Glasgow, pp. 187–193, 1904). Harker shows that the sills are preserved In granite and granophyre which removed the basalt that once inclosed the sills. The distribution of granodiorite and dikes and sills of all kinds is shown in Figure 1. The stippling is merely for the purpose of emphasizing the granodiorite‐

ISSN:0002-8606    

DOI:10.1029/TR016i001p00302-2

年代:1935

数据来源: WILEY

摘要:

Rocks of rhyolitic type in eastern Idaho and adjacent parts of Wyoming were observed by the Teton Division of the Hayden Surveys under Orestes St. John (Report of the geological field work of the Teton Division, U.S. Geol. and Geog. Surv. Terr., 11th Ann. Rep., pp. 498–504, 1879), who described them as trachytes. He noted their relations to different types of underlying sedimentary rocks and their tendency to conform with the preexisting topography, but considered them all as flow

ISSN:0002-8606    

DOI:10.1029/TR016i001p00308

年代:1935

数据来源: WILEY

摘要:

The general conclusions set forth in this paper are based on about five days' underground study and mapping of the Twin Lakes Diversion‐Tunnel, which was recently completed to divert water from Lincoln Gulch, on the west slope of the Sawatch Range, to the North Fork of Lake Creek, a tributary of the Arkansas River, on the east slope. The surface geology of the region was studied before the driving of the tunnel by J. W. Vanderwilt and A. H. Koschmann (Geology of the Independence Pass District, Colorado, U.S. Geol. Surv., preliminary report, mimeographed form No. 67484, 1932), and the general correlation of the tunnel‐section with the surface geology is based on the results of this work and consultation with the authors. More details regarding the general geology of the region are given in the report cited and in a report by J. V. Howell (Twin Lakes District of Colorado, Colo. Geol. Surv., Bull. 17, 1919) covering the region east of the Continental Div

ISSN:0002-8606    

DOI:10.1029/TR016i001p00321

年代:1935

数据来源: WILEY

摘要:

Several years ago, an investigation of phase equilibrium‐relations in the system NaAlSiO4‐KAlSiO4‐SiO2, was begun. These studies, now well along, throw considerable light on the composition of natural nephelite, on the pseudo‐leucite reaction, and on the possible courses of crystallization in alkaline magmas. The system, involving as it does, two common feldspathoids, leucite and nephelite,the alkali feldspars, and the forms of silica, is of great interest to petro

ISSN:0002-8606    

DOI:10.1029/TR016i001p00325

年代:1935

数据来源: WILEY

摘要:

The Blue Ridge and Piedmont geomorphic provinces, topographically distinct but geologically a unit, extend southwestward across eastern Pennsylvania and central Maryland, in a belt with an average width in these States of some 50 miles. In these provinces are exposed the crystalline formations of the Atlantic belt. Gneisses (with sporadic interbedded graphitic schist and marble), quartz‐schist, crystalline limestone, and scnlsts, constitute the pre‐Cambrian sedimentary series which has been folded, overturned, and overthrust with faulting, to the northw

ISSN:0002-8606    

DOI:10.1029/TR016i001p00328

年代:1935

数据来源: WILEY

摘要:

The syenites of the Coldwell District are located on the northeastern shore of Lake Superior near the Village of Coldwell (formerly called Port Coldwell), a station on the Canadian Pacific Railway. This interesting complex of alkaline rocks was first described by A. P. Coleman (Ont. Bur. Mines, v. 11, pp. 208–213, 1902) in 1901 although their presence had been suspected previous to that date due to the discovery of feldspathoid‐bearing rocks in the District. Coleman was the first to call attention to the similarity of these syenites to the alkaline rocks described by C. W. Brögger (Zs.Krystallogr., v. 16, 1890) in the Oslo (Christiania) District of Norway. The most complete study of the Coldwell Area was made by H. L. Kerr (Ont. Bur. Mines, v. 19, pt. 1, pp. 194–232, 1910) during 1906 and 1907. He was unable to come to any definite conclusions regarding the petrogenesis of these rocks, but demonstrated that practically every type of the Oslo District could be duplicated in the Coldwell Area. In his report, Kerr tentatively concluded (op. cit., p. 230) that “there is reason to believe that the whole syenite‐mass merely represents a peripheral differentiation phase of the fundamental gneiss (granite) found to

ISSN:0002-8606    

DOI:10.1029/TR016i001p00350

年代:1935

数据来源: WILEY