12 GEOLOGY or SIND. 



refers to some of the traps of Western India under the name of diorite, 

 it is not clear whether his diorites of Arabia be really that rock, or 

 coarsely crystalline dolerites. 



The peculiar interest attaching to any igneous rocks immediately 

 underlying beds associated with the nummulitic series arises from the 

 fact of that series having been found by me both near Surat and in 

 Cutch^ to rest unconformably upon basaltic rocks belonging to the great 

 trap series of "Western India. How far that series, so marvellously 

 developed in Hindoostan, can be traced to the westward, and to what 

 degree it is connected with the various volcanic rocks of the Arabian 

 Peninsula, is a question of peculiar geological interest. 



5. — General conclusions. 



Finally, I have only to recapitulate the principal conclusions at 

 which I have arrived, and to point out one or two of the most interesting 

 questions for future explorers in Sind to determine ; the conclusions are — 



\st. — The lowest bed of the nummulitic limestone north-west of 

 Kotree in Sind rests upon a considerable thickness of gypsiferous clays, 

 and sands, variegated in colour, producing alum and containing lignites. 

 These are similar to beds underlying nummulitic limestone both in the 

 Punjab and in Arabia. 



2. The lowest of these beds seen rests upon trap. 



The questions are — 



Isi. — Are the nummulitic limestones conformable to the gypsiferous 

 sands and clays ? 



2nd. — Do the latter belong to the nummulitic formation, or are they 

 older ? 



Srd. — Does the underljdng trap belong to the same series as the 

 great trappean formation of "Western India ? 



Sej)te7n6er 1866. 



* See subsequent paper. 



