452 



NATURE 



[March 9, 1905 



In the richest lodes the ores appear to have been con- 

 centrated by ascending solutions. 



In the third memoir we are transported some 500 miles 

 north-eastward to consider the economic resources of the 

 northern Black Hills of South Dakota. A brief sketch 

 of the general geology of the district is given in part i. 

 (28 pages) by T. A. Jaggar, jun., and the rest of the 

 volume, forming part ii., by J. D. Irving and S. F. 

 Emmons, deals fully with the economic resources. The 

 dome-like structure of the Black Hills, with theit laccolitic 

 intrusions of igneous rock, is already well known. " They 

 rise like an island in the midst of the Great Plains, with 

 culminating peaks of pre-Cambrian granite intrusive in 

 Algonkian schists, and these same schists and granite 

 may be followed outward from the centre of the Hills 

 to an encircling escarpment of Palaeozoic rocks dipping 

 away on the northern, southern, and eastern sides, and 

 mantling over the schists to form an extensive forested 

 limestone plateau on the west." The limestones have been 

 crushed in places into " pseudo-conglomerates," and Dr. 

 Jaggar suggests a similar origin for many supposed con- 

 glomerates or " intraformational breccias " that have been 

 described in other parts of the continent. 



The picture of the region presented in the first few 

 pages of part i. is remarkably clear and impressive. 

 The Cambrian series of shales, quartzite, sandstone, and 



The last memoir of our series, which takes us again 

 goo miles to the westward, is the description of a geo- 

 logical reconnaissance across the Bitterroot Range and 

 Clearwater Mountains in Montana and Idaho, by 

 Waldemar Lindgren, and is in some respects the most 

 instructive of the series ; but unfortunately we have no 

 space in which to do it justice. It deals with a vast tract 

 of mountainous country, for the most part exceedingly 

 difficult to traverse, and as yet very imperfectly explored. A 

 huge" batholith " of granite or quartz-monzonite 300 miles 

 in length from north to south, and 50 to 100 miles in 

 width, occupies the central part of this region, and has 

 been locally pressed and deformed, especially along its 

 eastern margin, into gneiss. Sedimentary rocks are com- 

 paratively restricted in their range, and the age of most 

 of those which are exposed is doubtful, as no well defined 

 fossils have been found ; but it is believed that, along 

 with complexes of pre-Cambrian age, the Triassic, Carbon- 

 iferous, and possibly older PalEeozoic systems are repre- 

 sented. In the west the country is overspread by the 

 great Columbia River lavas of Tertiary age. The physio- 

 graphic features of the region are of extreme interest,' and 

 are carefully discussed. It is shown that the Clearwater 

 Mountains had already acquired a sharpiv accentuated 

 topography before the outpouring of the Columbia River 

 basalts, and that the lower portions of the principal valleys 

 were flooded and dammed by the 

 lava-flows. The most important 

 structural feature of the region, how- 

 ever, is the great fault by which the 

 Bitterroot Mountains have been ele- 

 vated on the west and the Bitterroot 

 valley carried down on the east. This 

 fault-plane is described as being re- 

 markably flat, though apparently 

 normal. It is supposed to represent 

 a twofold movement, by which the 

 foot-wall has been raised and the 

 hanging wall depressed. It indicates 

 a vertical movement of from 4000 to 

 iiooo feet, and the horizontal com- 

 ponent is estimated to be at least 

 two miles. The schistose belt of the 

 granite underlies this plane, and the 

 structure is considered to be an out- 

 come of the disturbance. Move- 

 ment appears to have continued 

 along the fault up to recent 

 - times. 



G. W. L. 



Fir.. 2.- Upper V.illey of Mill C 

 pronounced U-shape of Valley n 



thin limestones, 200-400 feet thick, which rest in bold 

 unconformity upon the upturned edges of the Algonkian 

 schists, include at their base an irregular con- 

 glomerate, evidently an ancient beach-deposit. This 

 basal Cambrian conglomerate contains detrital gold, 

 derived from the erosion of auriferous lodes in the 

 Algonkian rocks, and, according to the present authors, 

 has been further enriched by later infiltration. It thus 

 constitutes in favoured localities a gold-producing ore 

 second only in importance to the lodes in the underlying 

 .'\lgonkians. The last-mentioned lodes are usually fissured 

 belts of rock along which the precious metal, accompanied 

 by other minerals, has been more or less irregularly de- 

 posited by permeating solutions. Another important source 

 of gold is described under the heading of " Refractory 

 Siliceous Ores." These ores represent the replacement of 

 portions of the Cambrian dolomitised limestones by silica 

 and other minerals, including gold, that appear to have 

 been carried upward in solution by waters ascending along 

 vertical joints. These waters, when checked by a com- 

 paratively impervious bed, tended to spread out laterally 

 along the dolomites, which were partially dissolved and 

 replaced by other substances. This part of the memoir is 

 illustrated with some beautiful plates of microscopic slides. 

 Besides gold, the district has yielded ores of silver-lead, 

 wolframite, and a little copper, with some traces of tin. 



NO. 18 45, VOL 7 l] 



ANTHROPOLOGICAL NOTES. 



A N interesting paper by A. L. Kroeber on the types of 

 ■^ Indian culture in California is to be found in vol. ii. 

 of the Publications of the University of California — 

 "American Archasology and Ethnology, 1904." Ethno- 

 logically, California is characterised by the absence of agri- 

 culture and pottery, by the total absence of totemism or 

 gentile organisation, by an unusually simple and loose 

 social organisation in which wealth plays a rather im- 

 portant part, by the very rude development of all arts 

 except basketry, by the lack of realism in art, by a slight 

 development of fetishism and by the conspicuous lack of 

 symbolism and ritualism, by the predominance among 

 ceremonials of mourning and initiation rites, and by a con- 

 siderable development of true conceptions of creation in 

 mythology. The natives are of an unwarlike nature, and 

 lack intensity and pride. It will therefore be seen that in 

 almost every instance the Californian Indians are among 

 the least characteristic of the Indians of North .\merica, 

 being lacking in the typical qualities of that race, and 

 thus they are the most generalised of the peoples of that 

 continent. In the same volume Dr. Kroeber gives an 

 account of the languages of the coast of California south 

 of San Francisco. 



Drs. A. Bloch and P. Vigier have re-examined the hair 



