December 26, 1901J 



NATURE 



17: 



of peculiar character. Considerable amounts of placer 

 deposits are found in the gravels associated with the 

 Neocene lake-beds. It is considered that some of the 

 mineral veins may be of Cretaceous or Eocene age, some 

 may be older, and others are post-Miocene. 



Mr. W. H. Weed describes the geology of the Little 

 Belt Mountains, Montana, an elevated and eroded 

 plateau region. Gneisses and schists form a central 

 core, upon which rest a great variety of sedimentary 

 rocks, penetrated by igneous rocks, which appear as 

 dykes, sills and laccolites. Silver-lead ores, gold, iron 

 ores and sapphire mines are described. The petrography 

 of the igneous rocks is dealt with by Mr. L. A'. Pirsson, 

 who describes syenite, monzonite, shonkinite (a basic 

 granitoid rock) and many other rocks. The rock in 

 which the sapphires occur is allied to the minettes and 

 shonkinite, and it appears to have derived its alumina 

 from clay-shales through which it was intruded ; the 

 molten rock on its way incorporating shale-fragments in 

 its mass. The many subjects dealt with in this elaborate 

 memoir are fully illustrated with view's, diagrams and 

 plates of microscopic sections of rocks. 



Part iv., on " Hydrography," deals with stream measure- 

 ments and reservoir sites, and there is a special article 

 on Nicaragua. The volume is well illustrated with views 

 and diagrams. Part v. is on " Forest Reserves," and 

 has excellent maps, views of scenery and woodland, 

 and notes on soils and timber-trees. Part vii., " E.x- 

 plorations in Alaska," is a volume of more than 500 pages, 

 profusely illustrated, and dealing with the topography, 

 geology, agriculture, game, and inhabitants. 



Mr. George H. Eldridge gives an account of a recon- 

 naissance in the Sushitna Basin and adjacent territory. 

 Here the geological formations include granite, schists 

 and slates, and a series of conglomerates and sandstones 

 of undetermined age ; also sandstones and shales with 

 coal-seams belonging to the Eocene ; and sundry Drift 

 deposits. Traces of gold occur in the pyritiferous quartz 

 of the slate series, but elsewhere in placer deposits. 

 The coal is a low-grade lignite. 



Mr. J. E. Spurr deals with south-western Alaska, and 

 his report is accompanied by a coloured geological map 

 showing gneiss and schists, Silurian, Carboniferous- 

 Devonian, Jurassic, Cretaceous, Eocene and later de- 

 posits, as well as Tertiary intrusive and volcanic rocks. 

 He describes as fully as possible the sedimentary and 

 eruptive rocks, and with regard to the latter employs the 

 name Alaskite group for certain quartz-alkali-felspar 

 rocks, and Belugite group for rocks transitional between 

 the diabasic and dioritic families. 



Mr. \V. C. Mendenhall describes the country from 

 Resurrection Bay to the Tanana River ; Mr. F. C. 

 Schrader deals with a part of Prince William Sound and 

 the Copper River district ; and Mr. A. H. Brooks with 

 the White and Tanana River basins. 



One general conclusion is that Alaska is eminently 

 not the place for the haphazard or untrained prospector ; 

 and that in the long run only those who have the intel- 

 ligence, training, and patience to study the conditions of 

 the occurrence of gold can hope to succeed. 



We have received the first and sixth parts of the 

 Twenty-first .Annual Report. In Parti, the director, Mr. 

 Charles i). Walcott, refers to the reorganisation of the 



feological branch which came into effect in July igoo. 

 he need was felt of closer and permanent supervision in 

 scientific lines, and the Geological .Survey was subdivided 

 and each division placed in charge of a specialist as 

 follows : — Areal Geology (stratigraphy, structure and pre- 

 Pleistocene physiography), Bailey Willis ; Pleistocene 

 Geology, T. C. Chamberlin ; Pateontology, T. W. 

 Stanton ; pre-Cambnan and Metamorphic Geology, 

 C. R. Van Hise ; Mining and Mineral Resources (dis- 

 tribution and production of economic minerals), D. T. 

 Day ; Economic (ieology (metalliferous ores), S. F. 



NO. 1678, VOL. 65] 



Emmons (non-metalliferous deposits, &c.), C. W. Hayes ; 

 Physical and Chemical Research, G. F. Becher. Ac- 

 companying this volume is an obituary notice of Prof. 

 O. C. Marsh, prepared by Mr. Arnold Hague. 



Part vi. consists of two volumes, dealing with mineral 

 resources. The great demand for mineral products led 

 to an increase in 1899 over 1898 of more than 10 per cent, 

 in output and of more than 39 per cent, in value. Nearly 

 every important "mineral" participated in this increase, 

 notably pig iron, copper, coal, natural gas, petroleum, 

 cement and stone. Lead showed a decline. The value 

 of grindstones was large and that of oilstones and whet- 

 stones the largest on record. Pigments, again, were in 

 great demand. Fuller's earth, was produced in less 

 quantity and more was imported ; it is used partly for 

 decolorising vegetable oils. 



We have also received a reprint from the Tw-enty-first 

 Annual Report, Part iii. (1901) — a Report on the 

 Geology of the Philippine Islands, by Mr. George 

 F. Becker, with notes on the Tertiary fossils, by 

 Mr. K. Martin. In these islands schists and mas- 

 sive crystalline rocks occur, together with diorites, 

 diabases, and gabbros. Of newer volcanic rocks there 

 are basalt, andesite, dacite, and probably trachyte and 

 rhyolite. A considerable number of volcanoes have 

 ejected ash and lava recently, or since the occupation of 

 the country by the Spaniards. Tertiary strata from 

 Eocene upwards are well developed in the islands, but 

 have been imperfectly studied. Of mineral resources 

 there is a brown coal of Tertiary age, while gold-mining 

 is an ancient industry. Even the tricks of the trade are 

 not unknown to the natives, and they "nearly succeeded 

 in inducing some American officers to take an interest in 

 gravel salted with brass filings.'' The auriferous deposits 

 include veins, placers, and river sands. The occurrence 

 of copper, argentiferous lead-ore, and magnetic iron-ore 

 is noticed. 



In addition to the Reports already mentioned, we have 

 received Nos. 163 to 176 of the Bulletin of the United 

 States Geological Survey, all published in 1900. These 

 deal with a variety of subjects, and not the least useful is 

 that by Mr. F. B. Weeks (No. 172)— a bibIiog:raphy of 

 American geology for 1899, in which 799 articles are 

 listed and indexed. 



Of purely geological articles we have a reconnaissance 

 in the Rio Grande coal-fields of Texas (No. 164), by Mr. 

 T. V. V'aughan. .•\lthough the State is by far the largest 

 in the Union, embracing a quarter of a million square 

 miles of territory, it stands low in the scale of coal pro- 

 ducers. The coals occur in strata of Upper Cretaceous 

 and Eocene age, and they vary in thickness from a few 

 inches up to 7 feet. Details are given of the strata 

 and their fossils, and it is remarked that there are not 

 yet sufficient data to trace accurately the boundary 

 between the Cretaceous and Eocene. The Cretaceous 

 coals of the Eagle Pass coal-field are regarded as of 

 anthracitic type, and as by far the best fuel in America 

 except the true anthracites of Pennsylvania. The Eocene 

 coal is strictly speaking a lignite. Mr. E. C. E. Lord 

 contributes a report on the igneous rocks of the San 

 Carlos coal-field. These rocks indicate late Cretaceous 

 or early Tertiary lava flows, and comprise rhyolite breccia, 

 quartz-pantellerite, and basalt. 



Contributions to the geology of Maine are made (in 

 No. 165) by Mr. H. S. Williams and Mr. H. E. Gregory. 

 Mr. Williams deals with the Silurian and Devonian 

 faunas, and enters into a discussion of the characters and 

 evolution of the Rhynchonellas. He remarks that there 

 is no question as to the great importance of internal 

 characters for purposes of determining the genetic 

 relationship of organisms ; but it is also a fact that the 

 external characters do not cease to be of similar value. 

 He points out that the taxonomic rank of characters rests 



