422 PROCEEDINGS OF THE ACADEMY OF [1897. 



massives, and the schistose and calcareous quartzites and sandstones 

 in other countries and in the Ourals. Of course if it be necessary 

 to accept the series D} c as Devonic underlying the quartzite series 

 Di g, this important quartzite member which is petrographically 

 and schematically such a striking analogue of the Cambric (Pots- 

 dam) or Primal quartzite is lost : but even then the group M is not 

 proven to be Devonic or even paleozoic by any evidence which it was 

 possible to present to the participants in such a long and compre- 

 hensive excursion. The writer does not mean in any way to deny 

 that evidence exists which establishes the original paleozoic character 

 of the group M, he only wishes to say that none such was seen by 

 those fellow members of the excursion of whom he inquired. Of 

 course long and patient investigation is required to place a critic of 

 the Russian Survey's proposed structure in a position to exercise his 

 office. If, after all, this scheme is to stand, it will add another 

 feature (and, perhaps, that which caused all the rest) in which the 

 Oural chain stands out alone among the mountain chains of the 

 world. 



Here then is the greatest of the cruces brought to light by the 

 labors of the Russian geologists, and laid before their guests at the 

 recent Congress. It is one which far transcends in interest and 

 importance the Volgian, Tartarian and Permo-Carbonic questions. 



The difference in importance between the problem of such a 

 structure and that of the permanent taxonomic value of the series 

 P-C, P-T, Pb (Tartarian), J-Cr (Volgian), Q K (Caspian), or 

 Cr v (Aptian), is that while in these latter cases the sequence is uni- 

 versally admitted, and the only question is whether the members of 

 these groups should be ascribed to one of the upper or lower series, 

 should be divided between them, or in whole or part should stand 

 alone ; the question in the first case is whether three of the great 

 mountain building systems are entirely wanting in the composition 

 of the Ourals. 



The peculiarity of the Oural chain which most strikes the observer 

 is that approaching from the western side the divide is reached 

 before half of the Paleozoic series are crossed, or any of the continent 

 backbone-making systems have appeared on the surface. From the 

 end of the first quarter of an ordinary mountain chain crossing, one 

 looks over the remaining three-quarters, (or where they ought to be) 

 into the boundless lake-covered steppes of Siberian Asia. But 

 another surprise is in store for the traveller. Approaching the Ourals 



