August 5, 1880] 



NATURE 



325 



mountains, which serves as a divide or water-parting 

 between the Atlantic slope and the regions lying to the 

 west. But though the traditional glories of the Rocky- 

 Mountains have thus been dimmed, and though the most 

 enthusiastic traveller through their still little-known soli- 

 tudes must in fairness admit that they cannot boast 

 among their innumerable ranges, hitherto visited and 

 described, one which for variety and majesty of outline 

 can be named with the Bernese Oberland, yet this merely 

 nominal degradation is more than compensated by the 

 discovery that these western territories contain a type of 

 high ground to which there is probably no adequate 

 parallel elsewhere on the face of the globe — a type so 

 strange and overwhelming in its first aspect, so weird and 

 almost incredible in its history, that the ordinary lan- 

 guage of scenic description fails to convey the impression 

 which the overawed beholder wishes to produce, and he 

 finds himself obliged to borrow a new vocabulary, yet 

 even with its aid is conscious that his narrative, exagge- 

 rated as it may seem, falls infinitely short of doing justice 

 to the marvels he has seen. 



To the portion of this region which, bounded by the 

 Colorado Park Mountains on the east and by the ranges 

 which border the Great Basin on the west, stretches from 

 Southern Wyoming far into New Mexico and Arizona, 

 the name of the Plateau Country has been given. It is 

 drained mainly by the Colorado River and its tributaries. 

 Its surface at lower levels than 7,000 feet above the sea 

 is a blazing desert, bright with strange mineral colours — 

 glaring red, livid purple, verdigris green, toned white, 

 and ashy grey. On these plains hardly any vegetation 

 grows. Not a solitary tree, save here and there a gnarled 

 cedar, affords a scanty shade, and little but stunted sage- 

 brush or prickly cactus in scattered tufts varies the eter- 

 nal monotony of the burning soil. It is a region of 

 perpetual drought, for the springs are believed not to 

 average one in a thousand square miles. Yet the land is 

 traversed by a network of rivers, which, however, wind 

 along in profound chasms, to be crossed only by the birds 

 of the air. So deep and sombre are many of these gorges 

 (that of the Colorado being in some places more than a 

 mile deep), that the very sound of their running waters 

 never reaches the level of the plateau above. Only a dim 

 daylight reaches the bottom, and the stars are said to be 

 visible in certain narrow gorges at midday. But where 

 the level of the plateaux rises high enough to condense 

 some of the moisture which the air-currents carry across 

 them the verdureless aspect of the lower plains is replaced 

 by luxuriant forests and open glades carpeted with rich 

 grass and wild flowers. So colossal, however, are the 

 table-lands that some of them slope gradually out of the 

 range of tree-growth to a height of from 11,000 to 12,000 

 feet above the sea, and almost lie within the limit of 

 perpetual snow. 



So far as yet known, the Plateau country reaches the 

 fullest development of its extraordinary features in the 

 southern portions of the Territory of Utah. This region 

 was partially explored by Prof. Powell during his sur- 

 veys from 1S69 to 1874, and by the parties under Capt. 

 Wheeler, especially by Mr. Howell and Mr. Gilbert, whose 

 published reports form a valuable portion of the third 

 volume of the " Geographical and Geological Explora. 

 tions west of the One Hundredth Meridian," conducted 

 by Capt. Wheeler. In 1S75 Mr. Powell secured the 

 sen-ices of Capt. Uutton for the investigation of a large 

 volcanic tract among the Utah Plateaux as part of the 

 survey under his direction. Capt. Dutton spent the 

 seasons of 1S75, 1S76, and 1S77 at the task assigned to 

 him. We have now the result of this labour in the hand- 

 some quarto volume and beautiful atlas which have just 

 appeared. This publication is undoubtedly one of the 

 very best of the many admirable contributions to geology 

 which have recently iDeen made by the official surveys of 

 the United States. With the aid of the letterpress, maps, 



and sections any geological reader can follow and realise 

 to himself the almost incredible magnificence, as well as 

 simplicity, of the structure of these high Plateaux. 



The geology of the area may be briefly described as 

 presenting a succession of nearly horizontal sedimentary 

 formations from the upper Carboniferous up to the 

 Eocene lacustrine deposits of the West, thrown into a 

 succession of broad folds, cut into segments by a series of 

 important faults, and overlaid towards the north by vast 

 sheets of volcanic ejections, the whole of the rocks, 

 aqueous and igneous, having] been carved into valleys, 

 gorges, escarpments, outliers, and isolated plateaux of 

 the most imposing magnitude. 



From the Carboniferous up to the top of the Cretaceous 

 seriesthere does not appear to be anygeneral physical break 

 in the continuity of the stratification. The Carboniferous 

 rocks are only partially exposed, but their overlying beds 

 • — the singular deep purple, chocolate, slate, and brownish- 

 red Shinarump group — attain a greater development, 

 exhibiting their peculiar regularity of sedimentation and 

 their sculptured terraces and outliers. These charac- 

 teristic strata have been classed as Permian or Lower 

 Triassic, but the researches of last year have, we believe, 

 brought to light fossils which point unmistakably to their 

 Permian age. An occasional want of conformability is 

 observed between them and the overlying Trias, but as a 

 rule the latter follow without discordance, and rise into 

 the succession of bright red and orange sandstones and 

 shales which constitute the great cliff-forming series 

 throughout the Plateau country. A geologist accustomed 

 to the scenery of the " New Red " plains of Central 

 England may find it hard to believe that the Trias 

 of Western America forms ranges of vermilion-coloured 

 cliffs 1,000 or 1,500 feet high, projecting in vast pro- 

 montories, retiring into deep bays, and stretching with the 

 same brightness of colour and the same regularity of 

 front for hundreds of miles. No very satisfactory line 

 has yet been drawn between the Trias and the Jura. 

 The latter series consists in the Plateau country of two 

 members, the lower being a massive grey or white sand- 

 stone of great thickness, the upper a series of calcareous 

 and gypsiferous shales from 200 to 400 feet thick. This 

 sandstone, according to Capt. Dutton, was laid down 

 over an area which cannot fall much short of 35,000 

 square miles, with an average thickness of more than 

 1,000 feet. Yet so persistent were the conditions of its 

 deposit that from [bottom to top, sometimes through a 

 depth of nearly 2,000 feet, it eveiywhere consists of 

 intricately false-bedded sandstone without layers or 

 partings of shaly or other heterogeneous matter. From 

 the Upper Jurassic calcareous] beds distinctive 'fossils 

 have been obtained. 



The Cretaceous system presents here the usual massive 

 development of sandstones and shales which form so 

 prominent a feature in the geology of the West. The 

 Lower Cretaceous Dakotah group is recognised by its 

 lithological resemblance to the corresponding beds in 

 Colorado and elsewhere, and by the occurrence of species 

 of Ostrea, Grypliaa, Exogyra, Plicatula, &c. The over- 

 lying shales are identified with the Laramie group, which 

 the author places as Upper Cretaceous. The whole of 

 the Cretaceous series is more or less lignitiferous ; a 

 considerable number of workable coal-seams in it being 

 already known. At the close of the deposition of the 

 Laramie group the first important break in the succession 

 of the rocks occurs. Extensive disturbance took place 

 along the old Mesozoic shore-line which now bounds the 

 Great Basin on the east, and this was accompanied and 

 followed by such enormous denudation that the Cre- 

 taceous series, several thousand feet in thickness, was 

 entirely removed and the oldest Tertiary strata accumu- 

 lated on the exposed surface of Jurassic beds. Yet so 

 local were these mo\-ements that in adjacent tracts the 

 whole Cretaceous series of ^the region is present, and 



