DESCRIPTIVE GEOLOGY : SLATE ZONE. log 



large thicknesses of the Trias limestone steeply dipping down the 

 east face of the ridge for some way (or else inverted) and then 

 thrown into great corrugations at the head of the glen under the 

 beetling crags of the Sirban peak. At other places in this glen- 

 bottom which opens towards Bazdar, where occur repetitions by faults 

 and folds, as shewn PI. 9 and Hor. section I, the Infra-Trias limestone 

 is occasionally seen intervening between the Infra-Trias quartzite 

 and the haematite ; but as we descend the glen the limestone rapidly 

 disappears from the section, until there is no trace of it, as already 

 stated, at Bazdar. 



The above section is interesting as definitely shewing a great 

 series of the white cherty banded limestones, distinctly overlaid by 

 the felsite and haematite (the latter being followed by the genuine 

 ordinary Trias limestone) and distinctly underlaid by the sandy 

 shaley and conglomeratic portions of the Infra-Trias. 



From the foregoing the relations of the Trias to the Infra-Trias 

 would appear to be that of unconformity. Nevertheless, it may be 

 worth while glancing at the situation in another light. A possible 

 if not probable, way of explaining it would be by assuming a rapid 

 thinning-out of the Infra-Trias limestones in a south-easterly direction 

 underneath the Trias. Let it be supposed that there was no original 

 deposition of the limestone in this direction at all and see how it 

 fits in with facts. There are certainly some aspects in which such 

 an explanation would seem plausible enough, but the chief difficulty 

 in the way is the short horizontal space available for such a funda- 

 mental change. Taking the thickness of the Infra-Trias limestone 

 at its thickest as roughly approximating to 2,000 feet, it is necessary 

 to imagine submarine conditions, whereby a deposit of this thick- 

 ness was continuously laid down in one area with nothing to repre- 

 sent it in an adjoining area separated by not more than four miles 

 (allowing for the compression of the region by folding and faulting). 

 On the other side of the question the only evidence against the un- 

 conformity is: — (1) The absence of any eroded or irregular sur- 

 face of the lower beds upon which the base of the Trias rests, and 



( 109 ) 



