Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/627

From Wikisource
Jump to navigation Jump to search
This page needs to be proofread.
MOYSISOVICS AND SCHLOENBACH—FLYSCH OR UPPER AUSTRIA.
3


The dip is at a high, angle, in a southerly direction, towards the Traunstein. The soft nature and inclined position of these marls cause slips; and the effect of these local disturbances is more or less perceptible at the present time.

Olive-green quartzose glauconitic sandstones appear to the north of the marls, abounding with Nummulites and other Eocene organisms. Still further north, the Grunberg is entirely composed of alternations of greyish-blue limestone containing fucoids, with Vienna sandstones which contains the characteristic vermiform markings whose nature is still undetermined.

The depression between the Grunberg and the Traunstein contains detrital matter evidently of glacial origin. It may be traced as far as the Laudach Lake, the north-eastern end of which it borders as a range of low undulating hills, evidently the remains of terminal moraines. Blocks of limestone from the Gschliefgraben lie scattered about, brought into their present position either by running water or by landslips. Moraines are also seen upon a terrace of glacial drift on the northern side of the Grunberg. The fine-grained calcareous and micaceous sandstones which are seen in situ on the west-south-western bank of the Lake of Laudach, between the Cretaceous marls and the Lower Lias, may possibly be concealed beneath these gravels and moraines. The sandstones in question are distinctly stratified, and dip southwards at a steep angle beneath the mass of the Traunstein. They rest immediately on, and pass into, a conglomerate composed of fragments of primitive rocks and rolled polished pebbles of white quartz, bound together by a ferruginouscement which is locally decomposed into rust-coloured matter. Organic remains are not rare, but they are usually so imperfectly preserved as not to admit of determination. The most abundant fossil is an Ostrea, strikingly resembling O. (Gryphea) obliqua; impressions of Lima and Pecten are also found. The Belemnites, which are probably derived from older rocks, have a decidedly Liassic facies. If the Belemnites are really derived from, and the Ostrea is identical with, O. obliqua, these conglomerates belong to the Lower Tertiaries; if this be not so, they must be placed either with the upper part of the Lower Lias or the lower division of the Middle Lias.

The calcareous sandstones above mentioned are lithologically identical with those of the upper region of the Gschlief ravine, which Mr. Stur placed in the lower division of Quenstedt's Lias β, on account of the evidence afforded by such typical fossils as Ammonites obtusus, Sow., A. stellaris, Sow., A. oxynotus, Quenst. (?), Ostrea (Gryphea) obliqua, Goldf. sp., Pecten Hehli, P. texetorius, Lima gigantea, Terebratula cor, Lam., &c.

In the same ravine are found blocks of splintery, occasionally schistose, grey limestone, containing isolated dark spots similar to those of the "spotted marls," and specimens of Ammonites margaritaceus,thus representing the middle subdivision of the Lias.

The above facts seem to prove that an inversion of the strata has taken place between the Lakes of Traun and Laudach, as has been