Structure of the Eastern Alps. 409 



the flanks of the primary ridge between the basins of Vienna and Styria. In 

 consequence of the enormous derangements of the chain, this group is brought 

 out in some longitudinal valleys within the limits of the secondary zone on 

 the north flank of the Alps; but, in general, it forms, on both sides of the 

 chain, the base of the great escarpments of secondary limestone, and rests 

 immediately on the upper strata of the central system.* 



4. The preceding group is surmounted by the great zone of Alpine lime- 

 stone, which is, in its turn, surmounted by, or passes into, a great series of 

 fucoid shales, green sandstones, and other rocks, referred to the green-sand 

 and cretaceous periods. The Alpine limestone, considered under the most 

 general point of view, is therefore on a parallel with the oolitic series. It is 

 separated, agreeably to the system of M. de Lill, into three great subdivisions. 

 The lowest is supposed to commence (at Bleiberg in Carinthia, and also in 

 the valleys of Abtenau and Gaisau) with beds of the age of the lias. The 

 middle subdivision contains the great, brecciated, saliferous deposits of the 

 Alps, which are, therefore, on a higher parallel than the deposits of rock salt 

 worked in England. The highest subdivision ends with the hippurite-rock, 

 which seems therefore of the age of some of our highest oolitic groups. This 

 last line of demarcation, though artificial, is the best we are able to adopt; 

 for the hippurite-rock seems to be more nearly connected with the Alpine 

 limestone than with the higher groups. But there are, if we mistake not, 

 many places where the upper Alpine limestone graduates insensibly into the 

 next superior group f. 



5. To the younger Alpine limestone succeeds a vast series of beds com- 

 posed of fucoid-shales and grits, green-sands and sandstones, cretaceous marls, 

 &c. &c. They are, as a whole, referred to the green-sand and chalk forma- 

 tions. The fucoid-shales may in some cases descend into the upper part of 

 the Alpine limestone ; but in general they seem decidedly subordinate to the 

 system we are describing. The upper part of the system, on the north flank 

 of the Alps, contains Nummulites and beds of arenaceous iron ore. On the 

 south side of the Alps, beds of nummidite limestone are in some places (for 

 example between Adelsbcrg and Trieste) very largely developed, and perhaps 

 descend as low as the Alpine limestone;];. 



* Supra, p. 307 — 311. The identification of this group with the new red sandstone was pub. 

 lished by Dr. Buckland in 1821 ; and was, in itself, a step of no ordinary importance ; as it at 

 once separated tlie whole zone of Alpine limestone from the order of transition rocks. About 

 the same time Mr. BakewcU was employed in making a series of independent observations in the 

 Tarentaise, which led him to similar conclusions : they were not, however, published before 

 1823. See "Travels in the Tarentaise," 2 vols. 



t Supra, p. 311—318. + Siqyra, p. 320—322, and p. 333, 337, &c. 



VOL. III. SECOND SERIES. 3 G 



