Records of the Geological Survey of India. 
[vor,. x. 
108 
I do not at present intend to pass beyond the subject of the tertiary zone further than 
to indicate briefly the rocks forming its supporting trough; and my notice of the newer 
formations will require less detail, because the rocks of the Salt Eegion beyond the Indus 
have been already described by me* as well as those of smaller areas in other parts of the 
district,! while a Memoir on the Geology of the Salt Eange is in the press. 
I must refer to Mr. Medlicott’s paper, just now mentioned, for an account of the 
important changes affecting the tertiary zone on its passage from the country in which 
it was first examined by himself towards this district. Following out the geological 
features, he finds nearly every stratigraphical peculiarity of the Simla area vanish to 
the west. Though the upper aud lower members of the great tertiary formation continue, 
the close identification of the intervening groups is still somewhat conjectural owing to 
the changes referred to. 
The discovery that the whole zone was subject to such extensive modification as 
the total disappearance of marked unconformities, gveat boundary faults dying out by 
conversion into axes of contortion, or disappearing amid parallel stratification, was wanted 
to reconcile the earlier observations made in the Simla area with my own later ones in 
this district. The diversity of structure in the two regions will account for my having found it 
impossible to say which portions of the great conformable series in this part of the Panjab 
represented each of the more clearly defined discordant groups of the Simla area; parti¬ 
cularly as there is a prevalent general similarity throughout all the upper groups. 
One of the local changes within the tertiaiy zone which may he analogous to the 
lateral variation affecting the whole formation as it passes westward, is the almost total 
absence of the very lowest beds of the sandstone series (as developed to the north) along 
the southern or Salt Eange side of the trough. On the Himalayan side the uppermost 
nummulitic beds pass by alternation into the lowest part of the Murree group. On the 
Salt Range the junction is sharply defined, the parallelism of the stratification being the 
same in both cases. 
Bordering this range there is a band in the sandstone series remarkable for the predomi¬ 
nance of red clays, which, from its colour and nature, led me to suggest its being representa¬ 
tive of the lower beds to the north. Below this zone, often close to the limestone, fossil 
exogenous timber is frequently found associated with reptilian remains. Similar petrified 
wood occurs in less quantity at a considerable distance upwards among the Murree beds on 
the northern side of the trough and Trans-Indus; but the red zone of the north, if present 
towards the Salt Eange, is not sufficiently marked to be distinguishable. If this fossil 
wood can be relied upon to fix an horizon, it shows that a large part of the basal sandstone 
and clay series of the north side of the trough had died out in south and south-westerly 
directions. 
In the Journal of the Geological Society of London,! I have discussed one of the most 
peculiar features ol the country—the marked abnormal contact which forms the main northern 
boundary of the detrital tertiary rocks : it is not a single continuous fracture, but composed 
sometimes of several contiguous lines of displacement, amounting to more than ordinary 
faulting, inasmuch as it is generally attended by strong inversion of the outer rocks; and 
whether the ground it traverses he at an elevation of only one or of six thousand feet, 
nearly the same group of the upper nummulitic beds is always exposed along its southern 
side. On the other side of the line both nummulitic and Jurassic formations are in 
contact with these upper beds, which occasionally transgress its limits. 
* See Nos. 17, &e., of list. 
f See No. 16 of list. 
