LOWER TRANSITION ROCKS. 133 



The Copper mountain offers a much less interesting succession 

 of rocks than does the Sandur synclinal. This is partly owing to the 

 fact that the sections are much less perfect, rendering it far from easy 

 to correlate the several members of the two synclinals, or even to feel 

 perfectly certain as to the identity of the principal beds at the opposite 

 ends of the synclinal. This is a difficulty that must exist in areas 

 where the strata have been contorted and fractured, and contain neither 

 fossils nor minerals whose distribution is sufficiently special to admit 

 of their being used to determine horizons. 



The most interesting section across this narrow and greatly 

 squeezed-up synclinal is to be traced from the 

 north-eastern corner of the great tank at Avin- 

 madagu, north-eastward for a distance of about 5^ miles at right 

 angles to the axis of the synclinal and at a point nearly equidistant from 

 the extremities of the great fold. The line of section passes but a 

 little eastward of the village of Tumati, after which 1 will call it. 



The succession of rocks obtaining here is the following : — 



South-west wall of synclinal. 



II. Haematite quartzite. 



10. Schists, hornblendic, &c. 



9. Haematite quartzite. 



8. Schists, hornblendic, &c. 



7. Haematite quartzite. 



6. Schists, hornblendic, &c. 



5. Haematite quartzite. 



4. Schists, hornblendic, &C 



3. Trap, a broad belt. 



2. Haematite quartzite. 



I. Schists, dark hornblendic. 



North-east wall of synclinal. 

 11. Haematite quartzite. 

 10. Schists, hornblendic. 



9. Haematite quartzite. 



5. Schists, hornblendic. 

 7. Haematite quartzite. 



6. Schists, hornblendic. 

 5. Haematite quartzite. 

 4. Schists. 



3. ^ Schists, a great thickness 

 2. ( of black and green horn- 

 1. ) blendic. 



Granite gneiss. Base not seen. 



The beds forming the north-east wall of the synclinal are slightly 

 inverted, while those of the centre are vertical and those of the south- 

 west wall have a very high northerly dip. I cannot help thinking 

 that only the basal part of this exceedingly deep synclinal fold now 

 remains ; the upper part, which included many of the beds represented 

 in the Sandur synclinal, having been denuded away bodily, — in fact, 

 only about half of the whole series has been allowed to remain. The 



( 133 ) 



