14 
Records of the Geological Survey of India. 
[vol. VI. 
described ; but their distinctness as a range is well marked by a line of low gaps and open 
longitudinal valleys along the geological boundary, the drainage passing through the range 
by narrow transverse gorges. These features may he well seen along the Western Dun 
under Masuri. In the Eastern Dun, from Raj pur to the Ganges, this flanking range has 
been removed ; but east of the Ganges it appears again in gj-eat force, continuing so up to 
the Nepal frontier. The strata aro well exposed along both roads up to Naini Tal. They 
consist principally of massive gray sandstone (very like the molasse of Switzerland), with 
subordinate bands of clay. The small nests of lignite found at many places in the sand¬ 
stone have more than once given rise to exaggerated hopes, and even to confident statements, 
as to the existence of coal. Tho fine hamiatite iron-ore of Dechouri near Kalidungi is 
only a local concentration of the iron oxide which occurs so freely disseminated as an ingre¬ 
dient of the clays. This middle member of the series has been called the Nahan group, 
from the chief town of Sirmiir. 
The Sivalik group .—The youngest member of the Sub-TIimalayan series is the Sivalik 
group, so called from the name given to the outermost range of hills by Colonel Sir Proby 
Cautley, who found in those rocks the splendid collection of vertebrate fossils-, partially 
described by Dr. H. Falconer in the Fauna Sivalensis. These hills are much lower than those 
of the middle group, from which they are generally separated by the broad longitudinal 
valleys known as the duns; which are structural features, not mere valleys of denudation. 
The form of disturbance of the strata is very regular : broad ‘ normal' anticlinal flexures, 
the axis-plane sloping towards the mountains. The Sivalik hills have been weathered out 
along the axis of the flexures; and the duns lie on the flat northern slope. The original 
* Sivalik Hills’ are that well-defined portion of the range between the Ganges and the 
Jamna separating the Dehra-Dun from the plains. From a short distance east of the 
Ganges the range is broken and scarcely recognisable, having probably been denuded off 
and covered up, if indeed it had ever been so prominent as to the west. The bhabar 
deposits here often reach up to the base of the inner range of tho middle group of rocks. 
The Patli Dun is an irregular valley of denudation in these hills of the Nahan group. 
Tho lower part of the Sivalik group is very like the Nahan group in composition, save that 
the sandstone is softer and fresher. At top there is a great thickness of conglomerate, both 
earthy and sandy. Tho physical separation between the Sivalik and the Nahan group has 
recently been clearly made out; hut the distinction was unfortunately not observed in the 
collection or tho description of the great series of fossils formerly procured from this region. 
The vast majority, if not all, of the large mammalian remains were obtained from the 
younger group ; some vertebrate fossils were found in the Nahan rocks, hut they were in 
great part lost or wore mixed with those from the Sivaliks; a very interesting point—the 
comparison of the two faunas—was thus missed. 
The limestone and slate series .—The second rock-system to be noticed consists of an 
unknown thickness of slates, limestones, and sandstones, forming the first range of the 
mountains from end to end. The stations of Chakrata, Masuri, and Naini Tal are on those 
rocks. The strata are greatly contorted, although preserving a strike approximately parallel 
to the mountain range; and the relations of the several bands of rock can now he only' 
vaguely suggested. From the more regular sections in the hills west of the Jamna the 
series has been roughly divided, iu descending order, into—The Ivrol limestone; the 
Infra-Krol slaty shale (often carbonaceous); the Blini limestone and conglomerate; the 
Infra-Blini slates. It is the Krol limestone that determines the picturesque outline of the 
outer ranges, as at Naini Tal, compared with that of the great mass of the Lower 
Himalayan region. The Blini limestone has also been traced eastward, along tho outer flanks 
of the mountains, to as far as under Naini Tal. The Krol group has been asserted to be of 
triassic age; but the only fossils certainly known to have been procured from these rocks 
