Structure of the Eastern Alps. 383 



the flanks of the Schwanberg Alp and the Pach Alp ; passes to the east 

 of Rosen Kogel ; and thence, in a sinuous line, bearing- in a north-easterly 

 direction, to the valley of the Mur, near Gratz. After doubling the old, cal- 

 careous promontory of Gratz, it ranges in an undulating; line, bearin^-on the 

 whole about E.N.E., through the ramifications of the Raab, making a deep 

 bay towards Weiz, which is on the primary system. Doubling the hills to 

 the N.E. of these ramifications, it ranges about N.N.E. into the Safenbach, a 

 few miles to the south of Pollau ; thence to Hartberg, skirting the talcose 

 and micaceous ridges south of Pollau and Vorau ; and from Hartberg, after 

 ranging for some way towards the north, and being deflected by the primary 

 ridge of Friedberg, it passes into the frontiers of Hungary. The accom- 

 panying map is on too small a scale to show the several demarcations in any 

 detail, and what we have now given is merely an imperfect sketch ; but it is 

 sufficient for our present purpose*. 



We entered the tertiary region at Gratz, and descended by the banks of 

 the Raab into the borders of Hungary. We afterwards examined the rela- 

 tions of the trachytic hills between the Raab and the Mur — the sections on 

 the banks of the Mur, from Radkersberg to Ehrenhausen— and the sections 

 laid bare on the banks of the Sulm, and other ti-ibutory streams which descend 

 from the Schwanberg Alp. Finally, we crossed the hilly region between the 

 Mur and the Drave, and traced the tertiary strata into contact with one of 

 the spurs of the Bacher Gebirge near Marburg. A second visit to these 

 regions, during the past year, enabled one of the authors to define the 

 northern and north-western boundaries of the tertiary groups ; by a traverse 

 from Friedberg to Hartberg, and thence to Gratz, Wildon, Voitsberg, and 

 Lankowitz. 



During these various traverses, we not only ascertained the general distri- 

 bution and relations of the tertiary groups, but also became in some measure 

 acquainted with the structure of the surrounding mountains. For example, 

 we found mica slate in the ridges north of Hartberg — talcose and micaceous 

 rocks near Pollau and Vorau — primary white limestone at Weitz — ridges, 

 apparently, of transition limestone, on the Mur above Gratz — mica and chlo- 

 rite slate, with garnets, atLagist — white, laminated quartz rock at Voitsberg — 

 a rock composed of white, flaky quartz and silvery mica at the Pach Alp — 

 mica schist, at the bottom of some of the deep water channels on the flanks 

 of the Radlberg — &c. &c. 



* Plate XXXV. Since this chapter was written, a beautiful, detailed, physical and geo- 

 logical Map of Upper and Lower Styria has been presented to the Society by His Imperial 

 Highness John Archduke of Austria. 



