

mnie 

36. Geological Notes on Hill Tipperah (including the 
Lalmai range in Comillah District). 
By Hem Cuanpra Das Gupta. 
1. As far as my ry ee goes, the State of Hill Tip- 
rah has never been visited by any pro- 
fessional geologist. I availed myself of 
a college vacation in May 1906 to make a tour through a portion 
of the State, and am deeply indebted to Mr. Ramani Mohan 
Chatterjee, M.A., at that time minister of the State, for giving me 
every possible ‘assistance. Unfortunately the time selected 
was inopportune. i reached Tipperah by the end of Moy; it 
was just at the commencement of the rains, and the interior of 
the country had become mostly inaccessible. 
Introduction. 
2. The main physical regent of the State consist of a 
seis system mountains and ee 
Ehysical aspect. parallel $e one another, and runn 
north and south. The average distance between any two conse- 
cutive ranges is about 12 mi and as one proceeds from the west 
to the east, the ranges ually increase in height. The princi- 
pal river valleys are all longitudinal, 7.e., coinciding with the 
©) th ranges. None o cehiener ak are navigable 
throughout the year, and only a few of them are so during the 
rains, These are the Gumti, Haora, Khoy4i, aes and Pheni. 
Just as there is a gradual rise in altitude of the successive ridges 
as we proceed from west to east, so do the floors of the interven- 
ing valleys also ascend independently of the slope of drainage. 
These orogenic features probably owe their sais to a pin 
period of upheaval. 
- 3. My observations were restricted to = reer eae et 
ily countr. e oldes up 0 
Fatikuli sandstone. fete | eae during my 5 eh tour, 
is represented by an unfossiliferous calcareous sandstone of great 
thickness which contained at its base some fragments of lignite. 
A woody structure is clearly observable in some of the specimens, 
‘ yhurous. This calcareous 
sandstone is abundantly developed in the Fatikuli subdivision of 
the State ; it is somewhat olive-coloured, and, besides quartz, con- 
tains grains of chloritised biotite, iron-ore and white pica. 
Zircon also occurs very sparingly. 
