Structure of the Eastern Alps. 385 



In the valley of the Sulm, and in some other deep ravines^ the waters have 

 cut through the whole tertiary series into a formation of transition or pri- 

 mary schist. Indeed the overlying strata, near the western limits of the basin, 

 have been deposited on so uneven a surface, that they never perhaps entirely 

 covered the higher protuberances of the older rocks. 



By a comparison of various sections we find that this lowest group admits 

 of the following subdivisions. (1.) Alternating beds of shale and sandstone, 

 with lignite. (2.) Alternations of marl and sand ; in some places containing 

 many marine shells. (3.) Beds of sandstone, with bands of sandy shale; and 

 (near the protuberances of the older rocks) with irregular, alternating masses 

 of conglomerate, containing rounded siliceous pebbles, and resembling the 

 shingle of an ancient beach. 



The second principal group is characterised by coralline and concretionary 

 limestone of a yellowish white colour: it is finely exposed in the escarpments 

 of Wildon, and in the hills of Ehrenhausen, on the right bank of the Mur. 

 The upper portions of this group occupy a considerable part of a hilly region 

 stretching on the south side of the Mur, in a direction nearly due east and 

 west, and are well exhibited in a succession of fine natural sections on the 

 right bank of the river. They are made up of marls, sometimes so calcareous 

 as to pass into irregular, concretionary masses of white limestone — of beds of 

 shale — and of sand and sandstone, occasionally so coarse as almost to pass 

 into the form of a conglomerate. 



The third and highest group contains, like the two preceding, beds of 

 marl and sandstone ; but it is distinguished by a great variety of fossils, by 

 beds of indurated, coarse, calcareous sandstone, and especially by beds of lime- 

 stone, here and there, exhibiting a perfectly oolitic structure. In this group 

 we include the yellowish, micaceous sands, with bands of sandy marl, and 

 occasionally with beds of small pebbles, which occupy a large portion of 

 the surface of the country near the frontiers of Styria and Hungary. 



In travelling from the western to the eastern side of Lower Styria we gra- 

 dually lose some of the grander features seen towards the Alpine boundary ; 

 and the country, chiefly composed of low, sandy eminences, becomes much 

 less beautiful and diversified as it sinks towards the neighbouring plains of 

 Hungary. An extensive region, which stretches across tlie valley of the 

 Raab from Riegisburg to the peaks of the Gleichenberg and the hills of 

 Straden and Potfendorf, offers however a striking exception to this remark. 

 Mountain masses of volcanic breccia, crowned with castellated ruins, flat-topped 

 eminences of basaltic lava, and domes of trachytic porphyry, rising above all 

 the neighbouring tertiary hills, give a new boldness to the outline of this 



VOL. III. SECOND SERIES. 3 D 



