504 Rei\ A. Irving — Tn'assic Deposits of the Alps. 



tile east side towards the lake, coupled witli the fact that while the 

 Triassic Limestone strata strike north and south along a steep 

 mountain -face on the western side, the slope of the valley above the 

 lake on the eastern side of it, which is roughly-speaking parallel 

 with the general dip of the strata, is composed of what appear to he 

 strata of the horizon of the Dachstein series, abounding as they do 

 with huge Corals of the genus Bhabdophylla [Lithodendron), which are 

 characteristic of this horizon. This view of the structure of the 

 valley is confirmed, when one ascends the Unnutz or the Hochiss, 

 which rise above the Achensee on the east side, and gets a vieAv of 

 the strike of the strata, repeating those of the eastern side of the 

 lake. Further, if this be the true explanation of the formation of 

 this lake-basin (a view which is strengthened by the fact that the 

 pass at Maurach at the southern end of the lake is not more than 

 40 feet above the level of its waters), it serves perhaps to explain 

 why this lake, which is said to be 2,500 feet in depth, fell 4 feet 

 during the great Lisbon Earthquake in 1755, and remained at that 

 lower level for some 24 hours. 



The section of the mountain-face above St. Cassian representing 

 a thickness of more than 4,000 feet, which has been given above, 

 may be compared with a typical section (after Mojsisovics) of the 

 Triassic strata in the northern Alpine zone. This is drawn through 

 the mountain-mass which rises above Saalfelden, and terminates in 

 the rugged peaks and huge crags of the Steinernes Meer, the profile 

 of which must remind an observer of the scenery of the so-called 

 ' Dolomite Alps.' The section (which is given in Credner's text- 

 book, fig. 273) is as follows : 



i. ' Dachsteinkalk ' \ -pv, *■• 



h. ' Korallenkalk ' j -^^^'^i". 



ffd. Dolomites of the Cardita-Schicliten \ 



a. ' Cardita-Schichten' ( t „„™ ■ir^,,^^,. 



/. White ' Wettersteinkalk ' ^°^^" ^™P'"- 



e. Eed ' Plattenkalk ' ) 



a. 'Virgtoriakalk' ) Muschelkalk. 

 c. Dark-coloured Limestone j 



b. ' Eauchwacke ' and dark-coloiired Limestones | fj^yij-p^ 

 a. Ked ' Werfener Scliichten ' J 



Figures 55, 56, 57, 58 in Giimbel's "Anleitung" give also well- 

 chosen sections illustrative of the Alpine Trias. 



To get a clear idea of the paljeontology of the Alpine Trias, a visit 

 should be paid to Prof. Zittel's splendid collection in the Munich 

 Museum. The ' Klipstein Collection' in the Museum of Natural 

 History at South Kensington requires yet many things to be added 

 to bring it up to the completeness of Zittel's, which is perhaps the 

 finest and most complete collection of the fossils of the Alpine Trias 

 in the world. 



The Triassic period was marked by the exhibition of considerable 

 volcanic energy in the Alpine area. The eruptive rocks of this age 

 are chiefly composed of augite-porphyry (e.g. in the Seisser Alp), 

 melaphyre (cutting thi'ough not only the strata of the Lower Trias, 

 but even sometimes the augite porphyries themselves; e.g. about 



