Structure of the Eastern Alps. 349 



At St, Pancratz an ancient chapel stands on the vertical edges of a highly 

 ferruginous numniulite-grit, containing numerous large Pectens and Echini 

 of the same species as those at the Kressenberg. 



At Mattsee there are two, parallel, low ridges composed of highly inclined 

 beds of grit, calcareous shale, and limestone, which run out into a promontory 

 separating the lake from that of Trum. The lowest of these beds are seen on 

 the lake of Trum, and are chiefly made up of calcareous shales, charged with a 

 Gryphaea (G.expansa*), which, after a careful examination, is found to differ 

 specifically from the G. Cohimba, or any known fossil of the green-sand and cre- 

 taceous period. These gryphite-beds dip at an angle of about 70° under a system 

 of thick-bedded, ferruginous, hard grits, full of Pectens and very large Echini. 

 The higher groups are interrupted by a denudation, into which extends the 

 southern end of the little lake of Mattsee ; and on its opposite side the older 

 members of the green-sand series rise out from beneath large accumulations 

 of alluvial matter. We are thus prevented, as at the Kressenberg, from tracing 

 any passage between the nummulitic system and the fucoid grits and shales. 

 The calcareous shale with Gryphites seems, however, to occupy a place in- 

 termediate between the two groups. 



As there is precisely the same difficulty in determining the relations of the 

 strata at St. Pancratz, we have little doubt that a great fault (similar in kind 

 and direction, and probably of the same age with that of the Kressenberg) 

 ranges through this part of the series ; throwing the ferriferous, nummulite 

 grits into a vertical or very highly inclined position, by the side of the older 

 and less inclined system of the green-sands and fucoid shales. Without 

 attending to these great derangements, which affect so many of the exterior 

 portions of the chain, one might form a very erroneous estimate of the relative 

 ages of the several groups of strata above described. 



Conclusion. 



To the east of the Mattsee we did not find any distinct traces of the num- 

 mulitic group; but we have stated enough in the preceding parallel sections 

 (commencing at the valley of the Rhine, and ending near that of the Salza), 

 to show its importance in the natural history of the portions of the chain above 

 describedf- Independently, however, of specific characters and the direct 

 evidence of sections, Nummulites prove nothing respecting the age of any 

 rock, inasmuch as the genus abounds both in secondary and tertiary for- 



* Plate XXXVIII. fig. 5. 



f We have before stated, that a secondary numrauli(e-rock is very largely developed in some 

 parts of the south flank of the Alps, and probably descends as low as the upper oolites. 



