May 10, 1895.] 



SCIENCE. 



523 



the numerous excellent cuts throughout the 

 text. Only the conclusions of the author 

 can be adverted to in the present Ijrief 

 notice. 



The eastern Aljjs have an east and west 

 trend and the section ;s normal to the 

 strike. The highest mountains have an 

 elevation of about ."ioUO m., and lie towards 

 the northern end of the section. The aver- 

 age elevation is 1800 m. In the northern 

 Alps there are three jwiucipal folds, in the 

 middle Alps four, aud in the southern 

 three, with many subordinate folds through- 

 out. None of these folds remain in their 

 original continuity. Fractures separate 

 one fi'om another and chop each of them 

 up into a series of blocks. By faulting on 

 these fractures the folded arrangement of 

 the strata is greatly distui'bed and ob- 

 scured. 



The special features of the faulting are : 



1. The prevalent dislocation of syncliues 

 in such a manner that their axial troughs 

 are thrust up and the wiugs dropped. 



'1. Anticlines with dropped crests so that 

 the newer strata of the crests appear below 

 the older strata of the wings. Not well ex- 

 emplified in the section. 



3. The occasional downthrow of the axial 

 troughs of syncliues with uplift of both 

 wings. 



4. The faulting of anticlines on longitu- 

 dinal axial planes aud the conversion of the 

 convexity of the anticlines into concavity 

 by subsequent compression. 



5. Thrusts. There are five important 

 overthrusts in the section ranging in in- 

 clination from 20° to 70°, the overthrust 

 in all cases being toward the south. 



(i. Cross fractures. Highly inclined to 

 the longitudinal faults and generally nearly 

 vertical. These are not expressible on the 

 profile, but are of the utmost importance 

 for a proper appi-eciation of Alpine struc- 

 ture. They are subsequent to the folds aud 

 associated longitudinal faults, and are the 



latest manifestations of the orogenic forces. 

 As such they have exerted a powerful in- 

 fluence upou the topography, giving the 

 Alps, in the opinion of the author, their 

 transverse draiuage outlets and many of 

 their lake basius. 



7. There are also faults which antedate 

 the period of Alpiue folding. 



In discussing the age of the folding of 

 the Alps the author makes it clear that 

 there have Ijeen at least two chief periods of 

 folding, one pre-Permian, and the other 

 post-Miocene. There were, however, dia- 

 strophic movements in the interval. This 

 is proved, first, by the faults which antedate 

 the later folding, and second, by the oscilla- 

 tion of the ocean border in the intervening 

 time. In discussing the latter argument 

 the author gives a series of nine pi'ofiles 

 showing the hypothetical relative distril)u- 

 tion of land and water over the Alpine 

 region in old Paleozoic. Pennian, 3Iu.^chelkalk, 

 Bhcetic, Liaif, Xeocotnian, Eocene, Miocene and 

 the Present. These show a trangressiou of 

 the sea up to the close of the Triassic, fol- 

 lowed by a steady recession from then on 

 to the present time. The sections, consider- 

 ed by themselves, might lend support to the 

 hjlJOthesis of Suess that the oscillation is 

 due to the variation of the surface of the 

 oceau. But other sections in neighboring 

 parts of the Alps give discordant results, 

 and it is concluded that the Alpine region 

 was the scene of diastrophic movement 

 between the Permian and Mioceue, whether 

 the ocean surface oscillated or remained 

 constant. 



The shortening of the arc of the earth's 

 surface in the line of the author's section 

 is 18 per cent., /. e., the region has, in con- 

 sequence of the folding, now only about 

 four-fifths of its original breadth. If the 

 folding of the central Alps be assumed to 

 be pre- Alpine, then the shoilening is re- 

 duced to from 12 to 13 per cent., or about 

 one-eighth. The author contrasts these 



