FAXIT 4.] 
Wynne: Geology of Mount Tllla, Punjab. 
83 
Comparing the two sections, it will be seen that the Nahun and Subathu groups, excepting 
the lowest portion of the latter, are probably unrepresented on Mount Tilla; purple sand¬ 
stones, if occurring at all. being quite inseparable from the remainder of the lower tertiary 
sandstones and clays, which, from th'eir fossils, were identified by the late Dr. Falconer with 
the Sivalik rocks. 
But little of the nummulitie (P Subathu) beds are seen at Tilla; and there is no 
appearance here of the unconformity to their underlying strata recorded by Mr. Medlicott, 
though this would not be reason for its non-existence. Omitting the red shaly and flaggy zone 
of Mount Tilla,—which is variable in thickness and not always present,—some parallel 
may exist between the calcareous pseudo-limestone with its underlying black shaly zone 
and the Krol and infra-Ivrol groups of Mr. Medlicott's unmetamorplno Himalayan series ; 
but even with the aid of that gentleman’s able memoir it would be hazardous at present to 
attempt the correlation of these rocks. 
Several beds of the sections to the westward have disappeared at Tilla; notably the 
black-shale group beneath the nummulitie limestone, containing all the coal and coaly 
deposits of the eastern portion of the Salt Range, and which can hardly he said to he repre¬ 
sented by a few traces of dark coloured shale, existing where they ought to come in. 
The true red salt-marl of the Salt Range makes but a very poor show along the 
southern base of Mount Tilla. It can he seen in somopkees near the villages of Nam and 
Pind Sevieki, hut is greatly overrun and concealed by detrital accumulations from the 
cliffs and hills above. Only 20 or 30 feet have been given for it in the section ; the thickness 
would, however, doubtless much exceed this if it could he well seen. It is of the usual 
bright red color, and gypseous saline nature; hut although srdt 1ms been manufactured 
from the impregnated water it discharges, no actual rock-salt has been found in it. 
The upper portion of the marl is, as usual, purple, and more shaly, and is frequently 
seen at the base of the purple sandstone cliffs. Its thickness, as estimated, may he too 
great, hut allowance has been made for a portion that is unseen in most of its exposures. 
This shaly portion of the marl passes up rapidly into strong purple sandstones of exactly 
the same color. They are generally fine grained, have no pebbles scattered through them, 
and, from being somewhat saline, have white efflorescences, yielding easily to the weather; 
they contain spangles of mica,; and the stronger beds, from the ease with which they can he 
dressed, are used as building stone. The thickness of this rock, from causes to be presently 
pointed out,, is sometimes deceptive. It forms a very considerable portion of some of the 
finest cliffs, where it cannot he much less than 300 feet, though in such situations its depth 
could he only estimated. 
Next above the purple sandstone is a strong hand of dark colored gritty shales and 
lighter colored sandy flags and layers (2); the whole having a lumpy aspect, and glistening 
with mica; the deposition surfaces are frequently glossy and covered with black earthy 
films. In these beds nnneliclan, crustacean or fucoid markings are numerous; arid else¬ 
where they have furnished the earliest traces of distinct fossils in the Salt Range, these con¬ 
sisting of small bivalve shells as yet undetermined ; strong ripple-marks also occasionally occur. 
Resting immediately upon this shaly zone is a massive hand of compact silicious sandstones 
and sub-calcareous rocks (3) of light color, often nearly white. Some of them are breeciated 
or pseudo-conglomeratic; and many, under the influence of the weather, assume the 
peculiar fantastic forms of decomposing limestone. A specimen of the latter variety from 
Mount Tilla yielded on analysis, according to Dr. Fleming, nearly equal parts of white 
quartzose sand, carbonate of lime, anti carbonate of magnesia. Their rough aspect and 
a peculiar surface appearance, as if likely to contain fossils, has led to frequent searches, hut 
nothing oi organic form has been found beyond the ohsoure tracks noticed in the foregoing 
group. The beds are frequently massive; this character, their strength and the association with 
softer beds below, having doubtless been the first conditions that resulted in the fine cliffs 
along the southern face of the range. Many valuable building atones could be obtained 
from this group, and some are said by Dr. Fleming to bear a high polish (Jour., Asiat. Soc., 
Beng., Vol. xxii, p. 265). 
The n<srt overlying group (4) is largely developed only at the western end of the range. 
It presents a strong contrast to that just mentioned, being formed of deep-red flag’s and 
shales, sometimes spotted with green, the flaggy slabs being often studded with projecting 
angles of casts ot cubic crystals, the mineral—in all probability salt—having been entirely re¬ 
placed by sand. The flaggy layers are frequently of light color internally, the bright-red hue 
