26 GEOLOGrlCAL MEMOIRS. 



it continues eastward into a range of mountains soon rising to a 

 considerable height. 



The chfF of Sprechenstein, of the great crystalline central mass of 

 the Tauern, begins eastward near the Gross-Glockner. The lines of 

 cleavage in it are vertical, or have a very steep southward dip. 

 Above JSterzing, the railroad has cut through considerable deposits 

 of gravel from the Eisack ; beneath it appear dark-coloured gneiss- 

 like slates, dipping JN'.E. 46°, in its steeper parts mica-schists 

 dipping north, in which garnets are said to have been found. 



JN'ear Strassberg, in the vicinity of an old Eoman road, a cut led 

 to the following deposits in descending order : — stratified sand and 

 silt, 38 feet ; ancient humus with isolated pebbles, 1|- foot ; sand 

 with Eoman (?) remains, 3 feet; small gravel, 1 foot; and coarse 

 rolled pebbles, 4 feet. Several pales, forced into the deeper layers, 

 were found beneath the ancient humus, as also (according to 

 reports) traces of carbonized straw. The tunnel by which the 

 course of the river Eisack is turned runs through hard quartzose 

 slates, overlain by thick accumulations of detritus, which abound in 

 the deeper portions of the Pfiertsch valley. These accumulations, 

 through which the railway is chiefly excavated in this locality, con- 

 sist of fragments of the above-mentioned slate, and of rhombo- 

 hedral fragments, frequently not more than an inch in diameter, of the 

 limestone constituting the ridge of the mountain above the slate. 

 The great Pfiertsch tunnel has been made entirely through this slate, 

 which dips N.W. and W.IN'.W., beneath the rocks of the Pfiertsch 

 valley, and are followed by micaceous slates and chloritic rock, with 

 numerous contorted layers of quartz. The tunnels of Pontigl and 

 Schellenberg have proved the occasionally micaceotis limestone of the 

 upper Pfiertsch valley to be divided into comparatively thin layers 

 imbedded in the quartzose slate, which dips about 30° or 40° JN". or 

 N.W. A white marble, in very thin layers, with a steep W.W.W. dip, 

 is seen above the Brenner post-house. Beneath it occurs light- 

 coloured quartzose mica-schist, dipping gradually steeper until it 

 rests vertically on the fianks of the Griesberg, a mass of hard gneiss 

 with large crystals of felspar. Enormous loose blocks of this gneiss 

 were found in the terminal moraine of the Yen valley. Similar 

 quartzose slates prevail on the northern slope of the central chain, 

 their dip varying between N.E., N., and S.W. ; in some places they 

 contain graphite. The Tertiary deposits are represented by blue 

 plastic clay and sands. 



The Castle Hill of Matrei, pierced by two tunnels and as many 

 shafts, shows two portions of thin-bedded limestone, abruptly bent 

 and imbedded in serpentine. Eemains of trees were found in a 

 yellow argillaceous substance (evidently the result of decomposition) 

 intercalated in the form of a wedge between serpentine and lime- 

 stone. Doubtful vestiges of gneiss and mica-schist appear once 

 more on the left side of the valley beneath Matrei, the railway, with 

 its numerous cuttings and tunnels, continuing its progress to Inns- 

 bruck through the laminated limestone on the right side. 



[Count M.] 



