44 8 



NATURE 



[March 12, 1903 



THE GEOLOGICAL SURVEY OF THE UNITED 



STATES. 



""PHE twenly-first annual report of the United States Geological 



■^ Survey is divided into seven parts. The first and sixth 



parts were received some time ago and were noticed in Nature 



for December 26, 1901. 



Part II. — General Geology, Economic Geology, Alaska. 

 There is an elaborate report on the geology of Rico 

 Mountains in south-west Colorado, by Messrs. Whitman Cross 

 and A. C. Spencer. The structure is that of a dome-like 

 uplift of sedimentary and igneous rocks, out of which a compact 

 group of peaks, rising above 12,000 feet, have been carved. 

 The igneous rocks appear partly in the form of laccoliths, but 

 the elevation is not in large degree due to the intruded masses. 



Devonian and Carboniferous rocks occur in the centre of the 

 uplift, with faulted masses of Algonkian quartzites and schists. 

 The great "Red beds" of Colorado succeed; they are partly 

 Permo-Carboniferous, but in the upper portion Triassic fossils 

 have been found. Jura- Trias and Cretaceous rocks also occur, 

 and igneous intrusions are found at various horizons throughout 

 the series. Some notable landslides are described, and it is 

 mentioned that, in recent geological times, the central mountain 

 region suffered severe shocks, which shattered the rocks at the 

 surface and to unknown depths. In consequence, landslides 

 have occurred when other conditions were favourable. 



A study of the glacial sculpture of the Bighorn Mountains of 

 Wyoming, by Mr. F. E. Matthes, leads to the consideration of 

 cirques. It is maintained that they have not been due to scour, 

 but rather to a natural quarrying process, essentially the product 

 of a " bergichrund " — a crevasse or line of crevasses — which 

 opens at a point between the moving neve and the quiescent 

 neve, and is practically the upper limit of glacial motion. The 

 author deals also with the effects of the occupation of valleys by 

 neve, and introduces the term nivalion to indicate its action as 

 distinct from glaciation. 



The Esmeralda formation in western Nevada, a freshwater- 

 lake deposit, is described by Mr. H. W. Turner. It is of 

 Middle Tertiary age, and contains fossil fishes and remains of 

 ferns, fig, oak, willow, sumach, soap berry, and tree trunks 6 to 

 S feet in diameter. It yields lignite, which may be of local 

 value for stationary engines, house use, &c. The plants are 

 described by Mr. F. H. Knowlton, and a new species of fossil 

 fish, Leuciscus turneri, is named and figured by Mr. F. A. 

 Lucas. 



The origin of mineral veins at Boulder Hot Springs in Nevada 

 is discussed by Mr. W. H. Weed. The veins have no special 

 economic value, yielding but small quantities of gold, silver, 

 copper, &C, but they are regarded as true mineral veins and as 

 due to deposition from hot water. The Boulder Hot Springs 

 are probably deep seated and connected with rhyolitic intrusions 

 which formed the latest manifestation of volcanic activity in the 

 region. It is believed lhat the gold is derived from granite into 

 which the rhyolitic rocks were intruded. 



The Eastern Choctaw coal-field is described by Messrs. J. A. 

 Taff and G. I. Adams. It is of Upper Carboniferous age and 

 forms part of the Indian territory, connecting the coal-fields of 

 Arkansas with those of Kansas, Missouri and Iowa. It yields 

 good bituminous coal. The Camden coal-field of south-western 

 Arkansas is reported on by Mr. Taff. This is of Eocene age, 

 and it yields a lignite which as a gas producer is said to be 

 inferior only to the best cannel coals. 



Reconnaissances in Alaska are reported on separately by 

 Messrs. A. H. Brooks, O. Rohn and F. C. Shradcr. These 

 reports will be serviceable to future travellers and prospectors, 

 as, in addition to geological and mineralogical notes, there are 

 observations on the climate, timber, game, natives, &c. A 

 useful list and explanation of Alaskan geographical names is 

 contributed by Mr. Marcus Baker. 



Part III. — General Geology, Ore and Phosphate Deposits, 

 Philippines. 



Mr. W. H. Hobbs contributes a memoir on the Newark 

 (Triassic) system of the Pomperaug valley, Connecticut. The 

 greater portions of the clastic rocks are reddish-brown sand- 

 stones and shales the constituents of which are mainly quartz, 

 felspar and mica ; they are, in fact, arkoses, composed of the 

 debris of granite and gneiss. The associated igneous rocks are 

 contemporaneous intrusions of lava, and attention is called to 



NO. 1741, VOL. 67] 



the production of secondary enlargement of quartz grains in a 

 shale-conglomerate at its contact with an overlying sheet of 

 basalt. The geological structure of the area is considered in 

 detail. Vertical or nearly vertical joint-planes have developed 

 in great numbers within the area, and an attempt is made to 

 determine the nature of the iaults along the joints and the 

 manner in which the area as a whole has been deformed 

 through the depression of the orographic blocks which the 

 joints have conditioned. Compression of the area in a nearly 

 east-west direction is believed to have found relief in the pre- 

 vailing dislocations. The drainage-system of the area is finally 

 considered, and it is found that the streams have been directed 

 in their courses to correspond with the direction of the pre- 

 vailing fault-series. The work of ice is also briefly discussed. 

 Mr. I. H. Knowlton reports on the silicified wood from the 

 Newark formation. 



The laccoliths of the Black Hills in South Dakota and 

 Wyoming are described by Mr. T. A. Jaggar, jun. It is shown 

 that igneous intrusions of rhyolite and phonolite accompanied 

 or immediately followed a great uplift in the area. This uplift 

 arched the horizontal strata of the plains into an elongated 

 dome, while schists beneath moved up irregularly on nearly 

 vertical plains of schistosity. The igneous matter arose through 

 the steeply inclined schists and spread out among the sedi- 

 ments which lay unconformably across the older rocks. The 

 intrusion is regarded rather as an effect than as a cause of the 

 great uplift. Mr. Ernest Howe describes a number of ex- 

 periments undertaken to imitate the processes involved in the 

 formation of laccoliths. These prove lhat low viscosity favours 

 wide lateral extension to form sills ; high viscosity produces 

 thick lenticular bodies. Moreover, the intrusive materia) 

 thickens into domes where a resistant overlying stratum locally 

 thins. A stratigraphical obstacle may also cause a sill to 

 thicken into a laccolith. 



The iron-ore deposits of the Lake Superior region are 

 further treated of by Mr. C. R. Van Hise. He points out 

 that the region is the most important in the world for the pro- 

 duction of the metal. In 1900, it yielded more iron than the 

 maximum product of Great Britain. He, however, mentions 

 that the exhaustion of the high-grade ores of Lake Superior 

 within a few decades is little short of a certainty. lie there- 

 fore urges that the material in which the percentage of iron is 

 below the present market demand and which must be handled 

 during present operations should be stock piled. The iron- 

 bearing formations are the Arch:ean, Lower and Upper Huronian. 

 The ores originated from cherty iron-bearing carbonate, and 

 to some extent the ore bodies are due to the oxidation of the 

 iron carbonate in place ; but they are mainly to be attributed 

 to the secondary enrichment by downward percolating waters 

 below crests or slopes, where such waters were converged by the 

 pitching troughs in the strata. 



The Arkansas bauxite deposits are described by Mr. C. W. 

 Hayes. At present, this mineral has been discovered in com- 

 mercial quantities in only three areas in the United States. The 

 Arkansas bauxite occurs in the Fourche Mountain district and 

 in Bryant Township. At Bryant, it rests on kaolinised syenite 

 and has a thickness of 10 or 15 feet, and in some places possibly 

 40 feet. While largely a chemical precipitate, it has some 

 features of an ordinary detrital sediment. Some of it is pisolitic, 

 while the whole is of this character in the Fourche Mountain 

 district. The deposits are considered to have been due to the 

 action of heated alkaline waters on the syenite, and to subse- 

 quent superficial chemical reactions on the deposits left by the 

 springs. 



The Tennessee white phosphate is also described by Mr. 

 Hayes. Much of it appears to have been formed by deposition 

 from solution in cavities of limestone. 



Mr. G. F. Becher's report on the geology of the Philippine 

 Islands has previously been noticed, a reprint in advance having 

 been received. 



Part IV. — Hydrography. 



This volume contains an elaborate report on the progress of 

 stream measurements for the year 1899, by Mr. F. II. Newell. 

 There is also a preliminary .description of the geology and water 

 resources of the southern half of the Black Hills and adjoining 

 regions in South Dakota and Wyoming, by Mr. N. H. Darton. 

 More precise and comprehensive knowledge of the artesian 

 waters in the Dakota sandstone and other widely distributed 

 water-bearing rocks rendered necessary a detailed study of the 

 area. Cambrian, Carboniferous, Jura-Trias, Cretaceous, Tertiary 



