Structure of the Eastern Alps. 321 



to be considerably expanded ; but in following it along a portion of the skirts 

 of the Bavarian and Austrian AIps^ we found it forming a zone of very irre- 

 gular breadth, consisting sometimes of a number of parallel ridges bearing 

 generally about E.N.E. and W.S.W., and sometimes thinning off to a single 

 ridge and almost disappearing. After stretching through the valley of the 

 Allgau and the ridges above Nesselwang (at both of which places sections 

 will be noticed), it gradually thins off at Fusscn, but again expands to the 

 east of the river Lech, and is still more expanded beyond the rio-ht bank of 

 the Inn. It offers most instructive sections near the banks of the Traun, 

 which will be described in their proper place; and from thence the slaty, fucoid, 

 calcareous grits and shales, form a succession of characteristic ridges, termi- 

 nating on the left bank of the Saal in the Hogl hills, which shut in, to the 

 N.W., a great bay or recess of the Alpine limestone. It deserves remark, 

 that the slaty, greenish sandstone of these hills, dips at a considerable angle 

 nearly south from the sides of the Staulfen, and directly towards the Unters- 

 berg, a mountain forming the northern skirt of the Alpine limestone between 

 Reichenhall and the Salza. Immediately north of the Untersberg, there is 

 only a thin and partial covering of the lower green-sands, but there is a large 

 development of the overlying cretaceous and nummulitic deposits*. 



The green-sand series occupies an extensive tract to the north of Salzburg, 

 extending into the hilly region of the Haungsberg, and thence without inter- 

 ruption to the Mond-see. At the southern end of that lake, the shales and 

 slaty sandstones, are placed vertically by the side of a precipice of dolomitic 

 Alpine limestone, but at its northern extremity they dip off" from the older 

 system, at a great angle, towards the north. 



The fucoid slates and grits occupy a considerable breadth, from north to 

 south, between the Mond-see and the Traun-see ; but to the east of the latter 

 lake they again thin off* into a narrow belt, so greatly displaced by an enormous 

 fault, that the upper system of nummulitic strata is thrown unconformably 

 against the precipitous face of the Traunstein, which is composed of Alpine 

 limestone f. This remarkable dislocation and inversion of dip, continues to 

 affect the formation in its eastward range beyond the Enns. 



* PI. XXXVI. fig. 9. 



f The physical outline of the group wo are describing (especially where it is but slightly ex. 

 panded) approaches very nearly to that of the tertiary series; so that in a hasty passage through 

 the country, when we have not an opportunity of examining the natural sections in detail, we 

 run an occasional risk of confounding one system with the other. It was in consequence partly 

 of this circumstance, and partly of the detestable weather which prevented us from examining the 

 gections at the base of the Traunstein, that we were led into an error in colouring the extreme 



VOL, III. SECOND SERIES. 2 T 



