R. D. Oldham — Essays in Theoretical Geology, 11 



3. The Siibathu group ; olive green, grey and red shales and subsidiary bands of 

 sandstone and argillaceous limestone, with a coal-seam and a peculiar ferruginous 

 bed at the base. It contains Nummulites and other marine fossils. 



The second area, forming part of the sub-Himalayas, is divided 

 from the Sirmur series by a great fault, and, in many places, by 

 a narrow strip of pre-Tertiary beds ; the series may be divided as 

 follows : 



1. Upper Siwalik ; soft sandstones or sandrock, conglomerates and some clays. 



2. liOwer Siwalik; soft sandstones or occasionally pebbly sandstones, and clays 

 mostly grey, but sometimes tinged with red, especially in the lower part of the group. 



3. Nahan group ; firm or hard sandstones iiiterbedded with clays generally nodular 

 and of a bright red colour, which are more abundant in the lower part of the group 

 than in the upper. ^ 



The series in the two areas combined appears to be much the same 

 as in the Murree hills. The Nummulitic Limestone is not developed, 

 and the marine deposits are much less in thickness; but there can 

 be no doubt that the Subathu group represents the Nummulitic 

 groups of Mr. Wynne. The Dagshai and Murree groups corre- 

 spond so closely in mineral character and stratigraphical position 

 that there can be no risk of error in correlating them, while the 

 two upper groups in the north-w^est are evidently the equivalents 

 of the three groups in the sub-Himalayas of the Simla region and 

 possibly in part of the Kasaoli group of the Sirmur series. 



To the east of the Ganges there are a few small outliers of the 

 Subathu group faulted and folded among the pre-Tertiary beds near 

 their southern boundary ; but with this exception the only Tertiary 

 beds known here or to the eastwards are confined to the Nahan and 

 Siwalik gi'oups." 



Besides these Tertiaries of the Outer Himalayas, beds of the same 

 age are known to exist at several places to the north of the main 

 snowy range ; but it is only in Cashmere territory that they have 

 been examined in any detail. In the Upper Indus Valley the 

 Nummulitics may be briefly described as consisting, at the base, of 

 coarse-grained sandstones, arkose beds and conglomerates, considered 

 by Mr. Lydekker to be of glacial origin ; thej' are certainly of 

 littoral origin, and indicate the close proximity of the original limit 

 of deposition. Above these come red, and green and grey shales, of 

 very similar type to those of the Subathu group, interbedded with 

 limestones: while at the top the series consists of a great thickness 

 of beds, mainly volcanic in their origin and basic or ultrabasic in 

 composition.^ 



The coarse-grained beds of littoral origin are confined to the 

 north-eastern boundary of the exposure, whose south-western 

 boundary is marked by great disturbance, and is in effect a faulted 

 one. It seems then that to the north-east the original limit of 

 deposition was not far removed from the present boundary, but 



^ Comp. Medlicott, Mem. Geol. Surv. India, vol. iii. part 2, chaps, i. and iii. ; 

 also Manual of Geology of India, vol. ii. chap. xxii. 



- Oldham, Rec. Geol. Surv. India, vol. xvii. p. 161 (1884) ; Middlemiss, Mem. 

 Geol. Surv. India, vol. xxiv. part. ii. 1890. 



2 Mem. Geol. Surv^ India, vol. xxii. chap. v. 



