INTRODUCTION. J 
and his account of tlie geology of that part traversed by him,^ render 
a correlation of the central with the eastern area a comparatively 
simple matter, and one which has been still further facilitated by 
the numerous detailed sections to be found in his memoir, as well as 
by his employment of European nomenclature in his description of 
the corresponding rock-systems of the Himalayas. 
In rapid or preliminary traverses of a previously unexplored area 
where, owing to paucity of fossils or to other 
Nomenclature. . . 
causes, the various sedimentary formations can- 
not be definitely referred to known European equivalents, the adop- 
tion of local names for the more prominent lithologica! units is no 
doubt advisable and even necessary, but when the survey has advanced 
to a further stage, and sufficient palseontological evidence can be 
adduced to determine the approximate homotaxial relations of the 
more important subdivisions, the multiplication of terms leads merely 
to confusion. In the present memoir this has been kept jn view, 
and the various systems have, so far as possible, been designated 
by the names of their European equivalents ; a few terms, how- 
ever, such as " Spiti Shales," and " Giumal Sandstone," which 
have now become historical and have been universally applied through- 
out the Himalayas, have been retained ; while others, such as " Par^ 
limestone," which have no special appropriateness, and may even 
include portions of two different systems, have been discarded. 
This applies especially to Mr. Lydekker's terms " Zanskar " and 
" Panjdl," under each of which names he included, as already stated, 
more than one European system, and where parts of the area 
surveyed by him have been touched on in the following pages, his 
terminology has not been employed. 
The geological map accompanying the present memoir is the 
joint work of the late Dr. von Krafft and the 
Maps* 
present writer, and is based on the " Atlas of 
1 Memoirs, G. S. I., vol. XXIII, pp. 206-223; Records, G. S. I., vol. XXII, 
pp. 158-167, 
B2 I 3 ) 
