STRATIGRAPHICAL GEOLOGY. 497 



standpoint. The palceontological sequence established in the 

 Alps was applied to the Himalayan development of Trias with 

 a few slight modifications. Waagen, Diener, and Mojsisovics, 

 who investigated the Eastern faunas, divided the whole of the 

 Triassic system into four series (Skytian, Dinarian, Tyrolean, 

 and Bajuvarian), further sub-divided into eight groups, fifteen 

 sub-groups, and twenty-two zones. 



At the present time, the general succession of the Alpine 

 Trias may be said to be fairly definite, but there is still some 

 variance of opinion regarding the parallelism of the Alpine and 

 extra-Alpine divisions. For example, there is no certainty yet 

 where the Alpine Muschelkalk may be said to end and the 

 " Lettenkohlen " group to begin; whether the Wetterstein, 

 Esino, and Marmolata limestones and the St. Cassian strata 

 may be referred to the uppermost horizons of Muschelkalk or 

 regarded as members of the "Lettenkohlen" group in the 

 Alps; again, whether the Lunzand Raibl strata in the Alps cor- 

 respond to the " Lettenkohlen " group or the lower Gypsum- 

 Keuper in the extra- Alpine development of Trias. 



G. The Jurassic System. In the very beginning of the nine- 

 teenth century the fundamental features of the Jurassic succes- 

 sion had been so securely established by William Smith that 

 subsequent observers had little to amend. The Jurassic 

 deposits have attained a remarkably typical and perfect de- 

 velopment in England. No serious obstacles of any kind are 

 interposed in the path of the observer; no great tectonic dis- 

 turbances, foldings, fractures, or high inclinations of the strata; 

 no sudden changes of facies, and no gaps in the sedimentary 

 series. The straightforward aspect of the stratigraphical rela- 

 tions, together with the characteristic lithological development 

 of each individual member of the series, and the extraordinary 

 wealth of fossil remains, has rendered England the classic 

 ground of the Jurassic system. 



William Smith at first treated the successive strata as equal 

 in rank, and although he afterwards (1815 and 1817) united 

 them into groups, these were not well defined and underwent 

 modifications before they were received into the literature. 

 Conybeare and W. Phillips comprised under the name of 

 Oolitic series all the strata between the ferruginous sand 

 (lowest Cretaceous) and the red marl (Triassic). The same 

 geologists classified the Lias as an independent basal forma- 



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