The Eocene and Miocene near Simla

OLDHAM 1893. Extract from Oldham's Manual of Geology, describing the colorful transition from the Dagshai to the Kasauli group near the main boundary thrust at Simla (pages 350-1) .

The Sabathu group is overlaid, with perfect conformity, by a great thickness of hard grey sandstones, interbedded with bright red nodular clays, known as the Dagshai group. The transition from the Sabathu to the Dagshai group though perfectly conformable is somewhat abupt, and marked by the presence of a group of passage beds , comprising a peculiar pisolitic marl with small calcareous concretions scattered through a matrix of red clay, a white sandstone full of irregularly shaped ferruginous concretions of some inches in diameter, and pure white sandstones associated with dark purple or liver colored shales, differing markedly in appearance from the general run of those above or below them.

The beds of the Dagshai group proper consist almost exclusively of two distinct types of rock. One is bright red or purple, homogenous clay; the other a fine grained hard sandstone of grey or purplish colour. The clays prevail in the lower part of the group and the sandstone, in beds of 10' to 15' thick, form but a small portion of the thickness, but in the upper portion of the group they increase, at the expense of the clay beds, till the top there is about about 200 or 300 feet of sandstones, with a few thin bands of red clay, which it is impossible to class definitely either with this group or the succeding one.

As will have appeared from the preceding paragraph, the passage from the Dagshai to the Kasauli group is perfectly transitional, indeed the distinction between the two merely depends on the absence of the bright red nodular clays of the Dagshai group. The Kasauli group is essentially a sandstone formation in which the argillaceous beds are quite subordinate in amount. The sandstones are mostly grey or greenish color and though some of the beds are as hard as anything in the Dagshai group they are, as a rule, softer, coarser, more micaceous, and in some places, distinctly felspathic.

PASCOE 1964: on page 1672 of E. H. Pascoe's Volume III Manual of Geology of India and Burma 1964 The stratigraphic section give by Pascoe is as follows:

Kasauli ( (Lower Miocene) Upper Burdigalian [15.9-17 MyBP ] Page 1639 Pascoe III

Dagshai (Lower Miocene) Lower Burdigalian [17-20.4MyBP] Page 1639 Pascoe III

Subathu (Upper Eocene) Upper Lutetian to Bartonian [45-37 MyBP] Page 1474 Paascoe III

Page 1671. The Jawalmucki Temple is built on the Dagshai shales in the Kangra region where the gas emanation presumably seeps from the unexposed Subathu beds through a fault zone.

Page 1671-2 In the Simla area the Dagshais of the type area are folded synclinally and are overthruist along their northeastern boundary by older rocks of the Krol series: this is well seen around the Pahmandra Hill as well as along the Blaini river. The Krol rocks, as well apparently as the thrust plane, have been bent synclinally, with the result that thin traces of the Dagshai beds are seen along the inner or northwastern margin of the sincline of older rocks. The Kasualis are exposed on the southeastern side of an irregular outcrop of Subathu beds which here separates them from the Dagshais.

In a footnote Pascoe states that "R. D. Oldham regarded the Dagshai and Kasauli beds as local variations of the same stage , but may have been confused by erroneous mapping. There is good reason to believe that there are two distinct stages of different lithology and age".

see also AUDEN 1933 1936 Records of the GSI 67 and 71 "In the neighbourhood of Kasauli, Auden finds a well defined white quartzitic sandstone intervening between the more typical Dagshai and Sabathus"