Bibliographical Notice. 427 



sum, are most folded and contorted ; and this ia especially well 

 illustrated by the clever drawings that illustrate the report. 



As a rule these are merely outline sketches, with but little 

 shading ; so that, though they are still most picturesque, nothing is 

 sacrificed to mere artistic effort, but every undulation is so carefully 

 indicated, and the lithological character even of the rocks so well 

 shown, that the nature of the country, both topographically and 

 geologically, can be most easily and satisfactorily studied. It must 

 not be imagiued from this that regular geological charts are neg- 

 lected. On the clearly printed surveys, in which the most intricate 

 contouring of the mountain-ranges never becomes indistinct or 

 obscure, the boundaries of the various deposits are indicated in 

 colours. 



But even here there is an improvement on the ordinary method 

 of manipulation. The colour is never dense ; generally only one tint 

 is used ; but the different deposits are represented very legibly by 

 cross-hatching, continuous lining, chain-dotting,- and other methods ; 

 so that the clearness of the plan is never interfered with. 



A remarkable and most complicated fold occurs in the Elk range, 

 and is illustrated by a group of sections at page 70, and an excellent 

 explanatory figure of the causes of the apparently confused arrange- 

 ment of the strata affected. The upheaval of the area, in parts 

 sudden and abrupt, has led to the cracking of the axis of the 

 fold, and the faEing-in and overlapping even of the upper strata ; 

 while at the ext -emities there appears to have been a more promi- 

 nent and extensive displacement, producing such fissuring of the 

 material as to lead to an extensive weathering and consequent 

 exposure of the lower beds ; but this has not been continuous 

 throughout the mountain-range produced. The complicated faults 

 so formed can be at once grasped bj^ an examination of the effective 

 sketch illustrative of the phenomenon. In fact the services of 

 skilful draughtsmen are everywhere apparent. The isolated weather- 

 worn pinnacles of the great valleys, the sombre scenery of the pro- 

 found canons, the grand picturesqueness of the moi;ntain of the 

 Holy Cross, on whose sides the snow-filled crevices are arranged in 

 the form of the sacred symbol, the effects of the protection afforded 

 by the hard bands of rock in softer materials, as in the " Monu- 

 ment Park," are all pori;rayed with effective artistic skill, and still 

 without any apparent sacrifice of truthfulness of appearance ; and the 

 value of such sketches as a compound of section-drawing and almost 

 a bird's-eye view is fully exemplified. 



In Palaeontology, with the exception of seven diagrammatic plates 

 of plants from the Cretaceous beds, the book has no illustrations ; but 

 perhaps it is scarcely fair to expect a lengthened account of the 

 fossils chai'acterizing the different groups in a general geological 

 history such as this is. The two monographs (by Leo Lesquereux) 

 on fossils in this report deal (1) with the plants by which the age 

 of the Tertiary lignitic formations may be determined, and (2) 

 with the Cretaceous flora of the Dakota group, those specimens 

 only being figured which are illustrative of the •' new materials 



