348 Professor Sedgwick and Mr. Murchison on the 



We believe that MM. de Lill and Boue^ as well as every one who has 

 recently examined this portion of the Alps^ identify the blue marls containing 

 these fossils with a portion of the overlying series of Gosau. As we partake 

 of this opinion, and intend to describe the Gosau fossils in a subsequent part 

 of the paper, it is only necessary in this place to state, that the shells of the 

 MarzoU marls, considered as a group, have unequivocally a tertiary character, 

 and that in the direction of our line of section they are overlaid by no other 

 regular deposit*. 



It appears, therefore, from the preceding details, that on the north flank of 

 the Untersberg, there is an uninterrupted series of conformable deposits, of 

 very great thickness, which may be naturally subdivided into the following 

 groups. 



1. Fucoid grits and shales resting on the hippurite-rock. 



2. A double group of cretaceous marls with a very characteristic suite of fossils, similar io that 

 which in England is found in the green-sand and chalk marl. 



3. A large, arenaceous group (graduating at its lower extremity into the preceding), abound, 

 ing in Nummulites, and with a peculiar suite of fossils, some of which resemble secondary, and 

 some tertiary species. 



4. An arenaceous and argillaceous group, the upper portion of which contains many shells of 

 genera and species considered characteristic of tertiary formations. 



There is nothing hypothetical in this arrangement ; it is, we believe, a 

 mere statement of facts as they occur in one of the clearest sections on the 

 northern skirts of the eastern Alps ; and the conclusions to be drawn from it, 

 are in accordance vvith those to which we have pointed in our description of 

 the former sections. 



7. Nummuliie-beds at Mattsee and St. Pancratz. 



Before we quit this division of our subject, we may shortly notice some 

 detached and nearly vertical portions of the ferriferous nummulite-grits at 

 St. Pancratz and Mattsee ; the former place on the north-western, and the 

 latter on the north-eastern, side of the Haungsberg ridge, which stretches to 

 the east of the Salza. 



* Dr. Boue (commenting on certain parts of our memoir, with which he became acquainted 

 through the abstracts of the Geological Society's Proceedings) contends that this section ought 

 to be prolonged to the Hogl hills north of the Saal. We reply, that to have extended the line 

 in that direction would have vitiated our section, inasmuch as the fucoid grits and shales to the 

 north of the Saal are thrown off from the Stauffenberg ridge, which plunges towards the south, 

 and are in no way directly connected with the Untersberg elevation. To have produced our 

 section to the Hogl hills would have made it not natural but hypothetical, and might have intro- 

 duced an error similar to that of our published paper, where we joined the saliferous breccias of 

 Hallein with the Untersberg ridge. (See Phil. Mag. and Annals, N. S. vol. viii. Plate 11. fig. "2. 



