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Betul District, Central Provinces.

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In January 1923 Mr. H. Walker resumed the geological survey of the Betul District, Central Provinces. The area surveyed is represented on Degree Sheets Nos. 55, and of the one-inch Topographical Survey and forms part of the northern drainage area of the Tapti river. The work is a direct continuation of that of the previous season and, whilst revealing no new features, has confirmed the opinions expressed in 1922.

Central Provinces.

During the season 1922-23, Sub-Assistant Durgashankar Bhattacharji continued work in the districts of Nagpur, Chhindwara and Wardha. The first part of the season was spent in a search for inliers of infra-Trappean rocks with a view to estimating the depth of the Deccan Trap and assisting in the question of water-supply in the town of Nagpur. No inliers, excepting those described by W. T. Blanford, were found. The mapping of sheet no. 55 was completed. Beyond a few small outliers of trap and a few unmappably thin layers of Lameta beds, the area was found to consist of an intricate complex of metamorphic rocks.

Chitral.

Mr. G. H. Tipper resumed his work in Chitral and spent there the period from April to the middle of October 1923. He was accompanied by Mr. E. J. Bradshaw, one of the newly appointed Assistant Superintendents. Owing to the heavy snowfall of the previous winter and to the broken weather throughout the season some of the sections which ordinarily would have been easily visible could not be inspected. Heavy falls of snow as low as the 7,000 feet level took place early in September.

One of the most interesting sections seen was up the valley southsouth-east from the village of Buni. Here the unfossiliferous lower Devonian limestones have been completely overfolded and faulted on both sides against narrow bands of Tertiary rocks, the Reshun conglomerates and shales. Associated with these Tertiary beds are Cretaceous limestones containing many Hippurites in a poor state of preservation. The latter beds are themselves faulted against the black slates and quartzites of the Chitral slate series. Still higher up there is evidence of another change of facies, a great mass of whitish quartzites are seen resting unconformably on the Chitral slates. In view of the Tertiary age of the Reshun conglomerates and shales, the suggested correlation between the succession in Chitral

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and that of the "Infra-Trias" and Attock slate series of Hazara loses much of its force.

'The high peak, Bini Zom (21,297'), and associated peaks are made up of banded gneisses and granites. Between Buni and Mastuj the road crosses the Reshun conglomerates and shales which are well exposed on the opposite bank of the river and beyond the conglomerates the Chitral slates are the only rocks. seen. The gneisses and granites, however, continue to form the high peaks south of the road.

From Mastuj to Harchin the road lies among black slaty beds and quartzites, lithologically like the Chitral slate series. In the valley draining from the north-west the Reshun conglomerate and shales are met with again. This is the continuation of the band seen last year running up the Shishi valley. The section at Harchin is, however, not very well seen. This band runs to the N. E. and forms the top of the Chamarkand pass where it has thickened a good deal and the conglomerate is very massive. It was unfortunate that the pass was under thick snow at the time, as the section promises to be a good one.

The descent from the pass to the camping ground at Chamarkand reveals a section in many respects similar to that exposed in the neighbourhood of Kala Drosh, and is very obviously a continuation of that seen by the late Sir Henry Hayden at Amurchat in Gilgit territory, although not quite so extensive. The Orbitolina limestones (middle Cretaceous) are present together with some trap beds. These beds abut on a mass of granite similar in all respects to that exposed at Mirkanni and at various places in the Shishi valley. Still further to the north-east the section is much thinner but the Reshun conglomerates and shales continue to form a well-marked band.

From Chapari, the hamlet at the place where the Chamarkand stream joins the Mastuj river, to the Baroghil pass, the traverse has already been so well described by Sir Henry Hayden that very little can be added. Details of sections have been obtained from the valleys on the left bank of the river, and the narrow band of semi-crystalline limestones which crosses the river at Tirbut has fortunately yielded a few recognisable fossils. There are some Bellerophon and some Fusuline, so similar to those from the Baro

1 See Imp. Gazetteer, India, Vol. I, p. 67 (1907).

ghil section as to leave no doubt that this band of limestone is of Carboniferous age.

In his description of the Baroghil section Sir Henry Hayden mentions a narrow band of ferruginous rocks which are faulted in amongst the Fusulina limestones. Traced eastwards this band thickens and becomes fossiliferous. Similar rocks and fossils are seen resting on the Permo-Triassic rocks of the Shawitakh pass. On the road to Shawar Shur these same rocks are seen occupying the centre of an overfold which has led to the reduplication of the Fusulina and other limestones, the latter rocks forming high scarps to the north of Shawar. From the fossils obtained these ferruginous rocks appear to be of upper Devonian age. They occur again in. the hills on the right bank of the Karambar valley and again also on the right bank of the large glacier south-east of Shawar Shur. The structure is one of considerable complexity.

The hills to the west of the Baroghil which promised to give a very fine fossiliferous section are disappointing, particularly as regards the Carboniferous and Permo-Triassic rocks. These rocks are much more highly disturbed and have become practically unfossiliferous, being converted into semi-crystalline limestones in which traces of fossils only are visible. The lower beds (ferruginous beds similar to those of the Shawitakh and Shawar Shur) are, however, very fossiliferous and there are signs of a distinct faulted junction between them and the upper beds. The general strike of all these formations at the Baroghil is E. to W.

Between the Baroghil and the Kankhun pass, parallel to the former and about 14 miles distant to the west, the rocks are much disturbed by a boss of granite and the Kankhun pass, instead of yielding a good section similar to that of the Baroghil, merely reveals masses of unfossiliferous marbles and black slates striking generally N. E.-S. W. Another great mass of granite, a little further west, has still further disturbed and metamorphosed the rocks. The good sections to be seen on the road across the Shah Janali pass and in the upper Turikho valley show that such limestones ast do occur have been converted into unfossiliferous crystalline limestones and the shaly beds into slates and schists. Signs of movement are very apparent in the folding of all the rocks, the thickening of the limestones and in the presence of many brecciated bands. It is probable that the greater part of the altered limestones are the representatives of the limestones of the Baroghil

but in the absence of any reliable fossil evidence it is impossible to place them in their proper sequence.

There is one unit exposed in the upper Turikho which deserves special mention. This commences in the neighbourhood of the Shah Janali pass as a series of black slates, grits and quartzites with some conglomerate bands. The outcrop gradually increases in breadth owing to the intercalation of epidotised trap rocks, of masses of conglomerate composed of white rounded quartz pebbles in a red ferruginous matrix and also of some detrital rocks of volcanic origin. Traced to the south-west these rocks pass into the softer black shales and quartzites forming the Kosht ridge. To these Sir Henry Hayden gave the name of Sarikol shales, from lithological similarity, and also suggested a lower Carboniferous age. The rocks are generally unfossiliferous but occasionally contain Orthoceras and crinoid stems. In the neighbourhood of Werkap a band of limestone occurs as part of these beds and is very fossiliferous. An examination of the fossils suggests that the limestones are probably upper Devonian and it may be that these beds are the continuation of the ferruginous beds of the Baroghil section.

At the end of the season an opportunity occurred for the reexamination of the fine section between Reri and Owir, along the Owir gorge. Although not quite so extensive as that of the Baroghil, the upper Devonian yielded a number of good fossils. As at the Baroghil there is a considerable thickness of beds above the horizon of the Koragh spur and Shugram which contain typical upper Devonian fossils. It was in this section that the peculiar pseudo-conglomeratic coral limestone was found; this band is so distinctive that it has been of great assistance in mapping detached outcrops.

The Orbitolina limestones of middle Cretaceous age in the Drosh valley have been traced along the edge of the river from just below Drosh fort to the cliffs opposite Suir. At the latter place the section exposed is more complete than at any other point. The limestones are sheared with the consequent destruction of the larger fossils. Orbitolina occurs in the more shaly bands between the massive limestone bands. The junction with the traps of the valley is always one of unconformity. The junction with the overlying beds is generally obscured by the alluvium of the river-bed. The fossiliferous Cretaceous beds do not continue along the strike either to the north-east or south-west, although a very thorough search has been

made in these directions. It is unfortunate that this datable deposit is of little use for the elucidation of the structure of the Drosh valley.

During last year it was pointed out that the Mirkanni granite is intimately associated with basic traps. Further examination of the sections near Mirkanni, Naghar, Badurgal and other places shows, according to Mr. Tipper, that the typical Mirkanni granite passes laterally through a diorite into a doleritic trap rock. It is this latter rock which occupies a considerable portion of the left bank of the Drosh valley.

Mr. Tipper notes one of the main agencies of denudation in Chitral which seems to have escaped previous observers. This consists of mud slides, the most destructive of which occur after heavy torrential rain such as that which accompanied thunderstorms during August of the year under review. This rain sweeps the small stones, dust, etc., from the hill sides into the stream beds. The material banks up and accumulates at the mouth of the stream where there is generally a gorge, and when the pressure has accumulated sufficiently, a stream of liquid mud, stones and boulders bursts through the obstruction and carries everything before it. The effect of these mud slides is amazing. In August, 1923, one came down through Chitral, a stream of mud and boulders of varying sizes. The material brought down blocked the main river threatening the fort of His Highness the Mehtar. The bursting of this temporary dam washed away the suspension bridge at the Government fort 1 mile below. The amount of damage done by these mud slides depends upon the character of the stream bed. When this has cut a fairly deep channel through the alluvial fan, the mud may be, and often is, confined between its banks, little material damage resulting. Where the stream bed spills on to the highest point of the fan, a mud slide simply spreads out destroying crops, gardens and houses, carrying away anything in its path. No part of the country is free from them. The amount of material thus transported is great and there is no doubt that the alluvial fans are chiefly built up in this way.

During the field-season 1922-23, a further 902 square miles. of the country west of Hyderabad were geoHyderabad, Deccan. logically surveyed by Mr. K. A. K. Hallowes. These areas are composed of biotite-granite gneiss containing much microcline and micro-pegmatite, probably of Archæan age, traversed by a network of numerous quartz reefs and intersecting

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