348 ME. A. B. WYNNE ON A FOSSILIFEROUS PEBBLE-BAND 



duction of such boulder-deposits recurred at intervals from the 

 very close of the Salt-Marl period (1) through the whole time of 

 the Purple Sandstone (2) and the succeeding Silurian Obolus- 

 zone (3), where present, and that of the Speckled Sandstone (5) 

 resting upon it, in the central and western parts of the Eange ; but 

 in the eastern portion of this there was a more marked interval 

 between the periods of the Oholus-heds (3) and the Speckled Sand- 

 stone (5), during which boulder-beds were not locally deposited at 

 the stage occupied by the Magnesian Sandstone (4). 



In detail, the western boulder-deposits are not suggestive of hori- 

 zontal continuity, but rather of fugitive lenticular distribution, 

 most strongly connected with the lower part of the series. In the 

 central parts of the Eange they are usually absent, or represented 

 by a few dispersed conglomeratic layers at various levels ; and in 

 the east they are associated with the newer groups, while in their 

 connexion and distribution in the " Olive Sandstones " (10) they 

 recall the lenticular character of the western beds sufficiently to 

 suggest a similar, later repetition of local conditions *. 



The boulder-beds of the Eastern area, then, despite a certain 

 amount of similarity, take their place upon a higher horizon than 

 those to the west, the group in which they occur overlapping, with 

 or without manifest unconformity, the Palaeozoic groups, which 

 themselves overlie, or are intercalated with, or represented by the 

 western boulder-deposits. 



In studying the relations of the Salt-Range Series on the ground,, 

 many of the natural groups, both in general aspect and in more 

 detail, were found to present the arrangement called " dove-tailing ; " 

 notwithstanding this it was clear that the lower part of the whole 

 series contained older Palseozoic fossils, and the upper part Meso- 

 zoic or newer remains. Thus far palseontological science has 

 assisted in unravelling the physical problems of the geology of the 

 Eange, and has furnished recently some additional details as to 

 certain of its most highly fossiliferous groups ; but the full record, 

 with its application, is as yet incomplete. If the dove-tailing 

 arrangement obscures the succession in one place more than another 

 it is in the region of the Kahun plateau, where the Magnesian Sand- 

 stone, the Speckled Sandstone, and salt pseud omorph groups all lose 

 more or less of their distinctive characteristics between the horizons 

 of the older Western and newer Eastern boulder-developments ; 

 and here the separation of elsewhere well-marked groups has been 

 carried out upon the best general or special indications which each 

 afforded. In this region, however, there was nothing found to 

 unite the two boulder-groups upon one horizon ; indeed, there was 

 less difficulty in referring the " Olive group," of which the Eastern 

 boulder-beds are members, to its place above, than in separating the 



* Possibly combined with some amount of unconformity, if the appearances 

 of a break exhibited on the road from Pind-Dadun Khan to Pid, which 

 Mr. E. Oldham noticed (Rec. G.[S. I. xix. pt. 2, p. 129), be accepted. The section 

 here did not escape my observation ; but the appearances of conformity else- 

 where led me to regard it as probably an instance of local contemporaneous 

 current-erosion. 



