NUMMULITIC SERIES. 57 



as nummulitcs in the paste, thus showing that even at an early date the 

 rocks of the group were irregularly distributed, and that limestones were 

 suffering degradation, while other beds of the same period were being 

 deposited, but at what distance from the former we have no evidence to 

 prove.* 



These sandstone beds have rather a local distribution, and appear to 

 be developed with, or as a part of, the clays or shales just mentioned. 



So situated as to overlie the clays, sandstones, and limestones de- 

 scribed is a zone of very dark- coloured limestone with rugged bands of 

 white chert. Fossils are rare in the band, except some few sections of 

 large, spiral shells and even less frequently a discoid gastropod heaving 

 somewhat the form of Flanorbis. 



Above these are gray, earthy, nummulitic limestones with some bands 

 of greenish shale, followed by thick and thin-bedded parallel limestone 



* The presence of such pebbles as these is always rather difficult to account for where 

 no absolute unconformity is known to occur. At first sight they might seem conclusive 

 evidence of the existence of an older limestone, its erosion, transport of its fragments, and 

 their deposition elsewhere. Limestones, especially these with nummulites, have been 

 often considered pelagic, the nummulites being supposed deep sea organisms, but that the 

 waters in which nummulites lived need not in all cases have been so very deep may be 

 considered proved by the manner of occurrence of the nummulitic beds — sometimes sand- 

 stones — of the Subathu group, exterior to the hill limestones lying northward from 

 Rawal Pindi. 



If some of the limestones could be supposed capable of consolidation near coasts 

 becoming thus liable to destruction by wave action the mystery might be solved, for I 

 have seen a sandy calcareous rock on the Indian shore of the Arabian Sea becoming 

 consolidated between high and low watermark, the recent shells in which were converted 

 into white limestone. Fragments of this rock, broken or worn down by the surf, would be 

 included in the sandy shore deposits containing the same shells, and yet be no evidence 

 of unconformity which, strictly speaking, requires the erosion of a land surface. Nor does 

 it seem unlikely that light bodies like nummulites might be removed, cast up by waves 

 and enclosed in a rock so formed, without bearing any prominent or visible traces of 

 having been rolled, in which case they would appear to have been enclosed where they 

 had lived. An old shore line, if it could be pointed out in these deposits, would complete 

 the analogy. This would of course indicate unconformity, but not among the shore beds 

 themselves. 



H ( 161 ) 



