Structure of the Eastern Alps. 389 



stones. The beds best adapted for this purpose are of a bluish <^rey colour, 

 and consist of smooth^ rounded pebbles of quartz, chlorite, schist, and other 

 primary rocks, varying- from the size of a pea to that of a pigeon's egg, held 

 together by a siliceo-calcareous cement. The upper and under beds are more 

 sandy and incoherent, but are equally charged with well-rounded pebbles ; 

 and, like the millstones, contain a few fragments and casts of tertiary shells. 



Other alternating beds in different parts of this valley consist of rubbly cal- 

 careous grit, passing into conglomerate, and of beds of fine yellow sand, sepa- 

 rated from each other by bands from two to three feet thick, of very coarse 

 calcareous grit, containing a few ill-preserved shells. These strata form the 

 highest members of the group we are now describing, and dip E. by S. at an 

 angle of about 15° (much above the average dip of the basin) under the coral- 

 line, white limestone of Ehrenhausen. 



The appearance of the millstone conglomerate so far within the western 

 limits of the basin, is, at first sight, difficult to account for, especially as the two 

 inferior groups contain no similar beds, and seem to have been deposited in a 

 tranquil sea. On examination, however, we find that the primary rocks are not 

 only laid open by the Sulm, but rise from its banks into high ridges protru- 

 ding through the tertiary formations on the west side of Ehrenhausen. By the 

 degradation of a portion of these ridges, which once existed as shoals or islands 

 in the old tertiary sea, the conglomerates in question were probably formed. 



The considerable inclination of the millstone group is also an anomaly 

 in the structure of the basin, in part perhaps explained by supposing the 

 deposits to have taken place on an inclined surface of one of the protruding- 

 primary masses. A local movement of elevation would, however, at once 

 account for the position of these beds ; and the supposition of some sucli 

 movement is perhaps countenanced by the presence of trap rocks further to 

 the north, in a corresponding part of the basin. 



Had our section commenced at the base of the Pach Alp, and been pro- 

 longed by the drainage of the Kainach over the summit of Wildon, it would 

 have crossed a series of beds nearly agreeing with those of the three groups 

 above described. On that line the millstone conglomerates are wanting, but 

 the trap rocks, above mentioned, may be seen in a knoll on the left bank of the 

 Kainach, about three quarters of a mile west of Weiterdorf, among the lower 

 tertiary groups which, by a slight easterly dip, are carried under the south- 

 western escarpment of Wildon*. 



* The trap is much concealed in a pine-wood, and the specimens brought away are in a state 

 of decomposition ; but they appear to be composed of basaltic greenstone, clinkstone, and clink- 

 stone porphyry. They deserve notice, as the only igneous rocks in this part of the Styrian basin. 



