﻿Vol. 64.] 



STRUCTUKE QV THE TAHNTHAL MASS. 



599 



Between these limestones and the conspicuously-foliated calca- 

 reous schists above them is a tolerably well-marked line of division, 

 which is probably of significance as regards the interpretation of 

 the tectonic relations. In passing from the bedded limestones to 



the calcareous schists 

 Fig. 4. — Section from Knappenkucliel to the 

 Nederer summit. 



Green 

 quartzites. 



Dolomitic 

 breccia. 



Calcareous 

 schisbs. 



Bedded 

 limestones. 



Massive 

 dolomite. 



Height above Sea-level 

 in Metres 



2763 Nederer 



there is no marked 

 change of dip ; and 

 some thin bands of 

 solid limestone ap- 

 pearing at intervals 



2690 



;^26i5 



2520 



_ 2505 Level of the lowest 



24,80 lake, Lower Tarn- 



^ thai. 



2150 



Floor of the cirque, 

 Knappenkuchel. 



in the schists may be 

 taken to show that 

 the plane of bedding 

 here coincides ap- 

 proximately with that 

 of foliation. 



Still higher up the 

 steep slope, on the 

 right bank of the 

 Lower Tarnthal, is a 

 very irregular band 

 of massive dolomitic 

 rock, freely traversed 

 by quartz-veins and 

 containing masses 

 of closely -cemented 

 breccia, the ' dolo- 

 mitic breccia.' In 

 this zone the effects 

 of shearing and crushing are displayed at their highest. Softer bands 

 of the rock have taken on a pi aty structure simulating bedding, and 

 are seen winding through and round the harder masses in directions 

 which bear no relation to the dip of the schists. Otherwise the 

 rock has shown itself to be singularly tenacious, and to have resisted 

 the shearing forces by which it has been kneaded into the more pliant 

 schists. The breccia is quite undistorted ; in the arrangement of 

 the fragments no one direction is predominant.^ Some fragments 

 seem to show the original bedding of the rock from which they are 

 derived. 



The schists are continued above the dolomitic breccia ; they become 

 richer in micas — bands and lenticles of green schist appear among 

 the grey. At about 2700 metres without sensible break the rocks 

 begin to take on the characters of the crystalline schists. These 

 include the green ' Tarnthaler Quarzit-Schiefer,' the ' Wetzstein- 

 und Dachstein-Schiefer," which occupy the summit-ridges of the 

 Nederer and the Sonnenspitz. The green rocks are dense quartzites 

 of exceedingly fine grain like that of a chert or hornstone. Ey 

 the addition of abundant minute plates of chlorite in parallel 



^ Dr. F. E- Sues?, however, notes distortion in the fragments of a similar 

 breccia at the Hippold Joch. 



