NATURE 



July 2 2, 1880] ^ 



mountains the evidences of glacial action are specially 

 strikin", one valley in particular bearing witness to the 

 former" presence of a glacier sixteen to eighteen miles 

 loner, extending for several miles into the low country, 

 where it threw down its heaps of moraine-stuff in mounds 

 a mile and a half broad, and from 800 to 900 feet high. 

 Next summer, however, the covering of snow having 

 partially melted, true glaciers of small extent were found 

 in the Wind River and Teton ranges. 



East of the ^Yind River Mountains there lies a suite of 

 palceozoic formations from the Potsdam sandstone to the 

 top of the Permian group, having a united thickness of 

 3,350 to 3,750 feet, and covered by 2,500 to 2,920 feet of 

 Triassic, Jurassic, and Cretaceous rocks. Dr. Endlich 

 computes the total depth of stratified formations in the 

 Sweetwater region at more than 16,000 feet. Underneath 

 them in the Wind River range lies a great series of 

 crystalline rocks. According to Dr. Endlich the Potsdam 

 rocks have been converted into quartzites by the same 

 metamorphic action which has changed the rocks imme- 

 diately below them into granites and schists. His section 

 shows three zones of granite in descending order, the 

 lowest of all being what he terms prozoic, while the 

 youngest, from its stratified or schistoid character, and 

 the coincidence of the inclination of its strata with that 

 of the overlying stratified formations, he classes as of 

 metamorphic origin. 



The researches of Prof. St. John were devoted to the 

 exploration of that wonderfully interesting region round 

 the head waters of the Snake River and the Teton 

 Mountains. The traveller who journeys wearily over the 

 vast desert lava-fields of the Snake River plains looks 

 wistfully from time to time at the great snow-rifted peaks 

 which the Teton range far to the east raises into the sky. 

 What would he not give for a glass of the cool water 

 which dashes down so profusely among these far moun- 

 tains and disappears so utterly before it reaches that 

 thirsty desert .' Extending the observations of Hayden, 

 Bradley, Comstock, and others, Mr. St. John has given 

 us an interesting narrative of the structure of the mountain 

 region and of the lower territory on its flanks. The core 

 of the Teton range, culminating in Mount Hayden, 

 consists of massive granites, gneisses, and schists, flanked 

 by quartzites and slates. On these ancient rocks lie from 

 500 to 1,000 feet of limestones, shales, and sandstones, 

 containing Lower Silurian fossils, and from 400 to 600 

 feet of a bufif-coloured magnesian limestone referable to 

 the Niagara group of the Upper Silurian. The Carbo- 

 niferous system, consisting mainly of limestones and sand- 

 stones, reaches a thickness of from 2,500 to 5,000 feet. 

 Secondary formations, referred to the Triassic, Jurassic, 

 and Cretaceous systems, attain depths of from 2,300 to 

 more than 5,000 feet. The volcanic history of this portion 

 of America is specially noticeable. According to Mr. St. 

 John's observations the usual chronological sequence 

 obtains in the areas traversed by him. The early erup- 

 tions have been of a trachytic nature, great variety of 

 aspect and lithological structure being traceable among 

 the various outflows. The surface presented by the 

 trachytic areas is markedly uneven — the result doubtless 

 partly of original irregularities of extrusion and partly of 

 subsequent extensive denudation. The latest eruptions 

 were of basalt, which has flooded the bottoms of the 

 valleys, and now covers an area of many thousand square 

 miles. Mr. St. John speaks of the diflerence of level 

 between different plateaux of basalt as being due to sub- 

 sequent elevation. But it is not necessary to suppose 

 that there ever was any common le\el for the outflows. 

 Some were no doubt poured out at much higher elevations 

 than others even in their vicinity. The same observer calls 

 attention to the remarkable volcanic conglomerates de- 

 scribed by Hayden from this and the Yellowstone region, 

 and by Whitney from the Territories lying further west. 

 These deposits, 3,000 feet or more in thickness, consist of 



269 



angular and subangular or rounded blocks of trachytes' 

 basalts, and other volcanic rocks imbedded in a dur 

 brown tuff-like matrix. They cover wide tracts of 

 country in the volcanic districts, and point to a phase 

 of volcanic or inter-volcanic action which is not yet well 

 understood. 



Dr. A. C. Peak contributes an interesting report on the 

 varied region lying to the north of the 41st Parallel 

 between Green River City, Wy., and Ogden, Utah. He 

 estimates the total mass of stratified formations in that 

 region from the base of the Lower Silurian system to the 

 top of the Quaternary series at upwards of 30,000 feet. 

 He has added some additional fossils to the list of Lower 

 Silurian forms collected from the district in 1 87 2 by the 

 late Prof F. Bradle)-. He has likewise made important 

 additions to the Carboniferous fauna of that area, and has 

 shown how dominant a part is taken by the 6,000 feet or 

 more of Carboniferous limestones and quartzites. The 

 Jura-Trias attains a depth of between 5,000 and 6,000 feet, 

 consisting of the usual red sandy and argillaceous strata 

 below, and passing up into laminated limestones and 

 shales. A considerable number of organic remains were 

 obtained from several zones in these beds, but they do not 

 vet appear to be sufficient for drawing a satisfactory line 

 between the Trias and Jurassic series in the Rocky 

 Mountain region. To our knowledge of the Cretaceous 

 and Tertiary geology of the district Dr. Peale was enabled 

 to make some valuable additions. 



Besides these geological reports, the labours of the 

 Survey in 1877 included a detailed palaeontological re- 

 search in the field by Dr. C. A. White, who contributes 

 an important report of his work, and the first of what we 

 hope will be a series of papers on invertebrate palaeon- 

 tology. He specially treats of the Cretaceous fossils of 

 the Western States and Territories. The topographical 

 work of the year was well done by Messrs. Nelson and 

 Gannett. As subsidiary but very valuable parts of the 

 work accomplished by the Survey, reference may be made 

 to the researches on fossil insects by Mr. Scudder of 

 Boston, which have been aided by the Survey and will be 

 published among its memoirs ; to the great monograph 

 by Dr. Leidy on the Rhizopods, which has already ap- 

 peared as one of the Survey's quarto volumes ; and to 

 the interesting particulars collected by the Survey regard- 

 ing the archaeology of the San Juan and South-Westem 

 Colorado. 



There will be, we presume, one further Report for 1878 

 —the last year of the existence of the Geological and 

 Geographical Survey of the Territories. Though this 

 mode of annual publication necessarily involves incom- 

 pleteness, and is apt to overload the reports with unim. 

 portant detail, there can be no doubt that the series of 

 volumes issued by this Survey form a permanent record 

 of great value, which for the districts to which they refer 

 wiU serve as the basis of all subsequent work. It is not 

 without regret that one can regard the cessation of these 

 volumes. On this side of the Atlantic, where they can be 

 calmly considered apart altogether from scientific rivalry 

 and political entanglements, they have been received with 

 general approbation. It is impossible not to be struck 

 by the largeness of the plan conceived by Dr. Hayden 

 for the scope of his survey. Not geology merely, but 

 every branch of inquiry touching the natural history, 

 archaeology, geography, and meteorology' of the Territories, 

 was embraced within his plan, and has been illustrated as 

 far as the means at his disposal would allow. To have 

 conceived this broad and scientific scheme, and to have 

 possessed the administrative power to secure and keep in 

 working concert so large and able a body of observers, are 

 qualities of no mean order, and deserve grateful recog- 

 nition wherever an intelligent interest is taken in the 

 general progress of science and in that human advance- 

 ment which scientific progress insures. 



Archibald Geikie 



