2 GRIESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



of that ground. Nevertheless I describe the geological features of 

 those parts in my text, and the figured sections, as far as I am able to 

 do so. 



The map No. I has been'reduced to the quarter-inch scale from the 

 large scale maps of the Survey of India, i mile = I inch, and conse- 

 quently the geological boundary lines will be found to be in much 

 greater detail than could be attained in surveying the Spiti ground, 

 of which only the old Indian Atlas sheets were available. The 

 boundary lines there had to be put in more or less diagramatically 

 only. 



I began surveying work in the Niti area in 1879, and continued 



my explorations amongst the snows during in- 

 Delay in publication. 



tervals, when I was not engaged in traveling 



on the North-West Frontier or in Afghanistan. My repeated expe- 

 ditions to the latter country have delayed the publication of this 

 memoir for a much longer period than I ever anticipated. The delay, 

 however, has enabled me to add explorations in the Hindu Kush and 

 Khorassan to my experiences, and so has made it possible for me to 

 compare the structure of the great Himalayas direct with that of 

 regions which stand in more or less structural connection with the 

 former. 



The number of previous writers on subjects, either purely geolo- 

 gical or related to the geology of the Central 

 Himalayas, is very great, but very few of their 

 papers afford real help in unravelling the complicated structure of the 

 ground. 



The following is an alphabetical list of the authors who have dealt 

 with subjects more or less connected with the geology of the Central 

 Himalayas or adjoining regions. In this list I have left out all papers 

 dealing with the outer Himalayas and the Siwaliks, excepting one 

 or two authors on the latter areas, who happen to express theories 

 applicable to the Himalayas generally. I also included papers, such 

 as Lydekker's Kashmir, which although not immediately relating to 

 the ground described in this memoir, yet has a close bearing on 

 questions which affect the geology of the Central Himalayas. 



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