732 



SCIENCE. 



[N. S. Vol. III. No. 72. 



opment, due to movements with respect to 

 baselevel, to glacial action, to wind action, 

 and to subterranean waters, are considered 

 in succession. These systematic chapters 

 are followed by others in which an excellent 

 outline of the physiography of Europe is 

 presented, with briefer treatment of the 

 other parts of the world. American read- 

 ers who desire to cite European physio- 

 graphic examples -will find this book very 

 helpful. It is illustrated with many dia- 

 grams and a good number of maps and 

 views; its detailed table of contents hardly 

 compensates for the absence of an index. 



THE INTERIOR PLATEAU OF BRITISH COLUMBIA. 



A RECENT report by Dr. G. M. Dawson 

 on the area of the Kamloops map sheet in 

 the interior of Columbia (Geol. Surv. Can- 

 ada, Ann. Rept. vii., 1896) treats in more 

 detail a portion of the region that the same 

 author has previously described (Physiogr. 

 Geol. of the Eocky Mountain region in Can- 

 ada, Trans. Eoy. Soc. Can., iii., 1890). 

 Considered in a broad way, and in contrast 

 to the mountains by which it is bordered, 

 the interior region may be regarded as a 

 plateau. Although deeply trenched by nu- 

 merous valleys of late Pliocene date, these 

 are lost to view when standing on the up- 

 lands, whose profiles run together to form 

 a nearly horizontal sky line. The plateau 

 is explained as a peneplain of subaerial de- 

 nudation. It is enclosed on the west by 

 the Coast range (not to be confused with 

 the Coast range or the Cascade mountains 

 of our Pacific slope), whose summits reach 

 remarkably uniform altitudes of about 

 8,000 or 9,000 feet. This equality is ex- 

 plained as the result of the rapid consump- 

 tion of any summits that may have for- 

 merly risen into greater altitudes, on the 

 assumption that the progress of denudation 

 in the partially snow-covered zone is several 

 or many times greater than below it. This 

 appears to be an interesting example of 



Penck's ' Oberes Denudationsniveau ' (Mor- 

 phologic der Erdoberfliiche, ii., 164). A 

 pronounced ' rain shadow ' and chinook belt 

 occur on the plateau district in the lee of 

 these mountains. Interesting details are 

 given concerning glacial action, lake ba- 

 sins, alluvial fans and terraces, and other 

 features. 



THE VOLCANIC GROUP OF TOPOGRAPHIC 

 FORMS. 



The chapter devoted to volcancos in most 

 physical geographies is chiefly concerned 

 with volcanic cones, so young as to be little 

 worn. The more thorough study and clas- 

 sification of geographical forms, as primarily 

 determined by structures and secondarily 

 modified by sculpture, greatly extends the 

 list of features associated with volcanic ac- 

 tion, even including the products of those 

 abortive attempts at eruption which have 

 been blindly satisfied before reaching the 

 surface. The buttes formed when these 

 ' plutonic plugs ' are revealed by denuda- 

 tion occur in fine variety of development 

 and expression in the region of the Black 

 hills of Dakota, and are described in the 

 current number of the (Chicago) Journal of 

 Geology, by Russell, with his customary 

 appreciation of physiographic relations. A 

 number of excellent photographs are repro- 

 duced as illustrations. The series of forms be- 

 gins with Little Sun Dance dome, an arch of 

 limestone, stripped of a great thickness of 

 overlying weaker strata, but unbroken, even 

 uncracked ; the igneous rock not yet re- 

 vealed. Mato Teepee, Inyan Kara and other 

 imposing buttes are fully revealed plugs. The 

 surrounding rims of harder stratified rocks 

 offer interesting examples of outer slope and 

 inface,* with inner subsequent vallej's, all 

 in concentric circular arrangement. One of 

 the illustrations is a view looking outward 



* The invention of tliis excellent term, tbe abbrevi- 

 ation of ' inward facing escarpment, ' should be cre- 

 dited to Mr. L. C. Glenn, of Darlington, S. C. 



