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Purple Sandstone, so that the Obolus Shales and Magnesian Sandstone have entirely dropped out of the scale of formations. The position of the Boulder-bed immediately above the Red Marl might of course be merely the effect of the continued overlap or unconformability that we have before alluded to in connection with it, on the accepted belief that the Red Marl is the oldest rock of the Range. But the relation of the Red Marl to the inverted series below is not altogether so simple, nor is the persisting thinness of it as a band or tongue, protruded along one of the thrustplanes following on the sigmaflexure, without certain noteworthy points.
The following is a condensed summary of the facts represented in Sketch Section No. 7, and in the near neighbourhood of that section:(1) The Red Marl appears along two lines crossing the section as thin bands,
and forming the cores of flexures. The upper one of these is associated with a fold of the rocks on the sigmaflexure pattern, in which the middle limb of the fold, though much reduced in size, is perfectly recognizable. The formations represented in the middle limb are, however, much crushed and torn along wavy parallel lines, a feature most marked
in the compact Speckled Sandstone beds. (2) The Boulder-bed is peculiar in some ways. It is a dark purple, inky
coloured shale, full of large and small boulders of crystalline rocks, and with light drab coloured sandstone beds associated with it. It sometimes
attains a thickness of 200 feet. (3) I could not find in the Boulder-bed immediately above the Red Marl a
single patch of the latter as a boulder or block; nor have I ever seen it, though constantly on the look-out for it, incorporated with any other formation. In the Boulder-bed near Pid, which overlies the Salt-pseudomorph zone, there are many patches of the latter rock as it were caught up and whelmed among the other boulders and rock fragments. In spite of the softness of the Red Marl, I think one would expect some trace of it also to appear incorporated in the Boulder-bed, were the latter truly of later formation than the Red Marl, as witness the boulder clays of England, especially in the neighbourhood of Cromer, in which
large masses of soft rocks are often whelmed. (4) In strong contrast to the bedded and sheared condition of the formations
included in the middle limb of the sigmaflexure, is the composed, homogeneous structure of the tongue of Red Marl, which is not more than 40 feet thick. It retains its completely unstratified aspect with a spongework of thin tabular plates of gypsum running through it in all directions and with thicker lenticular layers of gypsum. This point is, I think, of no small importance, for if the marl was passive under the sigmaflexural movements, it seems reasonable to suppose that it would have been sheared too. But it has not been sheared; there are no traces even of slickensides in it. Could this section be seen by a geologist unprejudiced by a previous theory, he would conclude that the marl band had been forced in a plastic or liquid condition through the rocks and had solidified quietly with the formation of the gypsum spongework under
conditions of no strain, after the earth-movements had ceased. (5) At the lower end of the glen, the very much disturbed sections show great thicknesses of the Purple Sandstone, too great to imagine thinned away within a few hundred yards. A more prominent unconformability at the base of the Boulder-bed than is elsewhere seen would no doubt account for this, but so would an abnormal position of the Red Marl
beneath it. (6) That the Red Marl is sometimes quite abnormal in its underlie is seen in
Sketch Section No. 8, Plate III, where it cuts across the Speckled Sandstone, changing its position abruptly from one inferior to the latter to a position above it and in contact with the Lavender beds. This position is paralleled by the one at Chambal mountain (west) mentioned by Mr. Wynne (p. 150 of his memoir) and explained away by faulting-an
explanation not altogether satisfactory. In Sketch Section No. 9, Plate III, there is represented a relation of the Red near
Marl to the surrounding formations very similar to that east mouth of the Golawala of Seran-ki-dhok. The thickness of the protruded tongue Khere glen.
of the Red Marl and gypsum is relatively greater, and it surges forward to the south like a foam-crest above a curling wave of Speckled Sandstone, &c. As before, it is difficult to believe that the Red Mari was a passive and solid formation when this forward ride across the edges of the Speckled Sandstone took place.
The distant hill of Purple Sandstone comes normally above the Red Marl and is of great thickness. Sketch Section No. 10, Plate III, is given for two reasons. In the first place it
exemplifies once more the sharp reflexed folding of the Section near Chideru.
de rocks in connection with the Red Marl, and in the second place it possibly explains those apparent interbeddings of the Red Marl with the Purple Sandstone which have been sometimes reported. It also shows veins of gypsum passing outwards from the Red Marl into the Purple Sandstone. These may however be merely secondary veins, and not due to any primary intrusive capacity of the marl. The next Sketch Section, No. 11, Plate IV, near Swas, is here mentioned, rather
out of place, on account of its similarity to No. 10. But Section near Swas.
chase besides the reversed folds involving the Boulder-bed and
besides the reversed fol Red Marl, there is a much fissured and drawn out inverted middle limb of an in. complete sigmaflexure to the south of the lower band of Red Marl.
It will be noticed that the apparent interbedding in the above section is in respect of the Red Marl among the Boulder-bed. This would be impossible as a real condition, if the interbedding with the Purple Sandstone be also granted.
I now come to the very important section two miles north Section two miles
S of Buri Khel. The following points were elucidated with north of Buri Khel.
special reference to the questions at issue :(1) The Boulder-bed is in direct conjunction with the Red Marl and its con
tained dolomitic and gypseous masses. It is of great thickness (more than 100 feet), of dark purple matrix, which is a fine hard clay splitting into little jointed pieces. In this and other respects it exactly resembles
the Boulder-bed of the Amb glen. (2) I paid particular attention in this locality, as elsewhere, to the included fragments, because, in its position here immediately on the top of the Red Marl, there seemed a chance that fragments of the latter might be found in it if the Red Marl had ever formed a floor on which the Boulder-bed was deposited. By the strictest search I could not find a single example of a boulder of Red Marl in the Boulder-bed. I could not find any patch or smudged blotch of it; no trace, in fact, that the
Red Marl was older than the Boulder-bed. (3) On the other hand, I found a considerable number of pebbles of a hard
compact, whitey-grey, sometimes faintly pinkish dolomite. (4) On going down to the Red Marl the cause of the large quantity of the
dolomite pebbles in the Boulder-bed above was made abundantly clear; for among the Red Marl there were large massive aggregates of it, which in the central portions exactly resembled the pebbles from the Boulderbed. I say the central portions advisedly, for, as a rule, the dolomite in the Red Marl, though generally resembling that present as pebbles in the Boulder-bed, was seen to differ from it in this particular : it was always honey-combed, or reticulate, with gypsum filling in the holes and meshes, as already mentioned in this paper. The finely punctured lumps and masses of the dolomite were the most numerous, and they were hard and
strong and well capable of forming into pebbles. (5) None of the pebbles of the dolomite in the Boulder-bed showed any punc
tures or ragged holes or any change anticipatory of a change into gypsum
least older than the Boulder-bed.
dolomite are of more recent age than the Boulder-bed at least, in as much as none of these rocks or rock structures are found included in the Boulder-bed, whilst the associated and rare unchanged dolomite is included in large quantities. A slight exception, however, is found in the layer (a few inches thick) of the Boulder-bed in immediate contact with the Red Marl. This is very noticeable, and along with it is a change in the colour of the matrix of the Boulder-bed, which instead of
being deep inky purple is a pale dull grey.
dolomite, and associated rocks, and the formation of the gyp-
(d) That the thin altered layer mentioned in the second paragraph (6)
is most probably a contact alteration. The following Section at Kalabagh, No. 12, Plate IV, has always been a puzzle
of no simple order on the accepted idea that the Red Marl is tion at Kala. the basal formation of the Range. I have copied it from bagh.
Mr. Wynne's own drawing (Memoirs of the Geological Survey of India, Vol. XIV, p. 269), as it is not his observations but his conclusions which must be called in question with regard to it. I have, however, altered the index names of the conglomerate and the Tertiary Sandstones, in conformity with later observations made by Mr. Wynne and by Dr. Waagen.
It will be observed that in that section the orange coloured beds (called the Orange series by Dr. Waagen in his Geological Results, Vol. IV, Part 1) are in direct superposition on the red, white, grey, or bluish-grey rock salt of the Saline series.
I infer from the following considerations that this junction cannot be a normal one due to the deposition of these beds on the top of some exposed reef of Salt Marl:(1) The Orange series, whatever be their particular age, undoubtedly belong
to the younger Tertiary epoch, and may with certainty be placed stratigraphically somewhere above the Nahan Sandstone and somewhere beneath the Upper Siwalik Conglomerate. Stated differently, they are the middle portion of a geological and petrological series, of immense extent and thickness, which covers vast regions on the North-West-frontier, along the southern borders of the Himalaya, and in Assam and Burma. Throughout this great extent of territory the middle rock-stages of that series are never found in superposition above anything but a lower stage of the same series. What is perhaps of more importance for the present argument is, that in the immediate neighbourhood of Kalabagh, along the very wonderful and striking section up the Indus river from that place, the same fact is above all manifest. There is no trace of uncon
formability in it. (2) A still more comprehensive local generalization may even be made. The
Tertiary system as a whole, though showing a distinct break between the Nummulitic Limestone and the Nahan Sandstone, does not anywhere in the Panjab exhibit the Nahans superposed above anything but nummulitic strata. Thus, there is no parallel instance anywhere in the Empire on which to frame a line of marked unconformability among the middle stages of the Upper Tertiaries, and we must therefore admit that the abnormal junction of the Orange series on the top of the Saline series is not due to the position of the Orange beds above, but to that of the Saline
series beneath. (3) A further point strengthening this conclusion is that the Orange coloured
beds, composed of soft sandstones and clays, or shales, begin as such immediately in contact with the salt-bearing beds. There is no basal conglomerate, and there is no gradual or rapid change downwards in the nature of the sediment of the Orange series as the Saline series is approached—nothing to indicate the beginning, at this point, of a set of
detrital rocks of such marked features and extent as those of the Upper
Siwaliks. A painting with the foreground and middle distance cut away would not more plainly indicate mutilation than does this ruptured section of the Orange beds.
According to Dr. Waagen, the whole of his Red series, Grey Sandstone series, and Purple series, which come beneath the Orange series, are absent in this Kalabagh section, whilst they are in full thickness fuither up the Indus river.
In the Sketch Section above, I have copied from Mr. Wynne's figure, because I think it truly represents the relation of the rocks visible on the river face.' In his Trans-Indus memoir (Memoirs, Geological Survey of India, Vol. XVII, part 2, p. 46) a section through the same hill, but along a different line, is given. As it primarily represents other points, the above relation of the Orange series to the Saline series is not given due prominence.
I cannot here enter into a lengthy discussion of the many other features of disturbance so remarkable in the Kalabagh hill. I refer the reader to Mr. Wynne's Trans-Indus Memoir, pp. 41 and 42. The laboured explanation there given on the accepted age of the Saline series will be at once seen to be unnecessary, if, as I have advocated, we look on the latter as having formed part of a liquid magma forced into and among the rocks in a quasi-intrusive fashion.
I will conclude by drawing attention to one final point. As we travel westwards from Kalabagh, the Salt series (Red Marl, &c.) appears no more in what has hitherto been called its normal position. One isolated patch of it appears some eight miles up the Lunai N., but among the Siwalik Sandstones. If the latter means anything, it indicates that the Saline series is trending northwards; whilst the outcrops of the older strata (previously in contact with the Salt Marl) are, as will be seen from Mr. Wynne's Trans-Indus map, trending southwards, or in the opposite direction.
The salt-bearing beds, indeed, seem to have become divorced from the older rocks of the region, and become insinuated among the Tertiary strata. Hence the appearance of the rock-salt of the Kohat region at a Tertiary horizon offers less difficulty to the understanding than before. Notwithstanding the reported differences in appearance between the Kohat salt and that of the Salt Range (as to which I can say nothing from personal experience) I think that, being an appearance and nothing more, it should not carry much weight, when balanced against the strong presump. tive evidence in favour of their common origin inherent in the whole circumstances of the case. There now remain to be briefly mentioned some few inliers of the Red Marl at
two or three places. On the plateau part of the range the Inliers of the Red Red Marl, with gypsum and sometimes rock salt, appears in
the form of little oases among the younger rocks, interrupting them. I was greatly impressed by these occurrences on reading Mr. Wynne's memoir and examining his map, for they seemed utterly at variance with what would be expected of a dormant stratified rock. I was confirmed in this opinion after Mr. Datta and myself had visited the localities; but owing partly to the gentle lie
i Perhaps a little exception may, however, be taken to the violent nature of the contortions in the Orange series. The curves might have been much more gently represented, if the true vertical scale in relation to the horizontal had been adopted.