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THE GEOLOGICAL SURVEY OF INDIA.

RECORDS

Fall.

OF

THE MERUA METEORITE. BY G. H. TIPPER, M.A., F.G.S., F.A.S.B., M. INST., M. M., Superintendent, Geological Survey of India. (With Plates 18-27).1

1925

THIS

HIS meteoric shower named after the village where the largest fragment fell, occurred on the 30th of August, 1920, at approximately 11-15 A.M. Mention is made of the fall in the Annual Report of the Geological Survey of India of 1921. (Rec. G. S. I., LIV, p. 10). The circumstances attending the fall are narrated by Mr. B. Circumstances of the Srinivas, Deputy Magistrate, Allahabad, who was deputed to report on the fall.

ALLAHABAD
CITY

From the report it appears that in all six pieces fell, the largest at Merua, 2 pieces at Manpur Urf Baghai Kalan, 1 at Chukri, 1 at Umri and 1 at Mustafabad. The location of these villages in relation to Allahabad is shown in the accompanying sketch plan.

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1 The plates illustrating this paper were prepared by one of my colleagues who had hoped to write the description but was prevented by circumstances.

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All these falls took place simultaneously, the exact time of which is not known, as the villagers had only a vague idea of the time of day. Superficial examination will show that they are parts of one mass, and must have fallen at one time."

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The big piece fell down at Merua in a field. It was a cloudy day and hence nobody saw any flash. The stone came in a slanting position from the east, and went down six feet inside the earth obliquely. A small boy named Tahal had seen it coming. There was a sharp thundering report at first, and it was followed by less noisy detonations. The boy told me that on hearing the first sound, somebody told him that it was going to rain, but it kept on rumbling. Then there was a whizzing sound as if something was coming down. The boy says that he thought the cloud itself was coming down, everybody was frightened, and he himself left cutting grass and fled. He says that he saw something like a kite coming down with a great velocity from the eastern portion of the sky. The stone was coming down with a loud whizzing noise, and did not leave any trail behind. Nobody went near it at once as everybody was afraid. After two or three hours the villagers mustered courage to dig out the place."

"It may be mentioned that the first loud noise was clearly heard at Allahabad. I myself heard it and a friend of mine happened to look at his watch at the time as he took it to be the gun from the fort. It was exactly 11-14 A.M., when the noise was heard in Allahabad."

Urf Baghai Kalan.

"Two pieces of stone came down in Manpur Only one piece was seen coming down by Nimai. Nobody witnessed the fall of the other piece. It was forty feet high when Nimai saw it coming from the east. It went down 1 feet inside the earth in a slanting position, and this man went and picked it up soon afterwards. It was a little warm and grew cold soon. At Mustafabad only one piece came down, and nobody saw it in the sky. Ganga, who was 8 or 9 bighas away when the piece fell down, found it to be quite cold when he went there and picked it up. It went a few inches inside the earth."

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One piece came down at Chukri. Datadin saw it coming down from the east and the piece went obliquely a few inches inside the earth. Datadin found it a little warm when he picked it up. The fall of one piece at Umri was not witnessed by anybody. Bhagwati picked it up after some time and found it quite cold."

Five pieces of the fall were received from the Collector of Allahabad. These weighed, respectively, (a) 56-689 kilos, (b) 9.197 kilos, (c) 3-019 kilos, (d) 1-544 kilos, and (e) 957 kilos, the total weight of these portions of the fall being 71-406 kilos. Of these (c) and (d) were sent originally to the Government Laboratories in London, in connection with the research on extra-terrestrial chlorine. These two portions are illustrated on Plate 25, figs. 1, 2, 3. On analysis in which 23 grammes of material were used, no chlorine was found and the remainder was presented to the British Museum, Natural History Section. Portions (a), (b) and (e) remained in the custody of the Geological Survey of India, where they bear the number 279 in the meteorite collection.

The following is a description of the physical appearance of portions A, B and E which are with the Geological Survey of India. Portion A (Plates 18-22), weight 56.689 kilos.

Physical Appearance. This large mass has suffered badly from fracturing, probably on impact and after. The general shape is so well shown in the illustrations that there is no need for further description. The crustal surface (Plates 18 and 22) is almost entirely covered with pits of varying sizes. Many of these are comparatively shallow, the ordinary thumb markings of meteorites. These are often arranged in group separated from each other by well defined but shallow ridges.

The most striking feature of the original surface is the presence of a number of extraordinarily deep depressions (Plate 18, middle). This line of deep depressions is met at right angles by another line, and the second line by a third (Plate 22).

The crust is quite uniform, almost black in colour, and covered by a network of fine black glazed lines.

The fractured surface (Plates 19, 20, 21) shows two noticeable features. First, an obscure rectangular jointing, second, a large number of rust covered surfaces, some plain, some curved and lying at all angles through the mass. These surfaces are seen to penetrate and disappear into the unfractured rock. Some of them can be traced to very considerable distances through the meteorite as thin brownish lines. At first sight, it seemed that these surfaces were similar in origin to the slickensides which are commonly developed in meteorites during fracture. Careful examination showed that this explanation would not account for all phenomena observed. If these were newer slickensides, they would have been confined

entirely to the fracture and would not have penetrated the unfractured rock. In selecting a small portion for micro-section, an opportunity offered of seeing what these surfaces would look like, when freshly developed. They are grooved and are steel-grey in colour, and the rusty brown colour of the exposed surfaces is due to oxidation in the moist climate of Calcutta. I have personally little doubt that these planes are really the remainder of an originally brecciated mass of rock.

Portion B. Weight 9-179 kilos, Plates 23, figs. 1 and 2, and 24, figs. 1 and 2. The whole is a portion of a much larger individual. The fractures, Plate 23, fig. 1, right hand bottom corner, Plate 24, fig. 2, left hand, Plate 24, fig. 1, right hand,-are of an older fracture and show a bluish rather shiny covering not scoriaceous like the original crust. There is one oblong slightly grooved area shown in Pl. 24, tig. 2, which resembles an ordinary slickenside. The fresh fracture, Plate 23, fig. 2, shows a light grey rock marked by glistening metallic points and yellowish chrondules. In this fresh fracture there is a band of much darker material running obliquely across. This patch suggests that there is probably differentiation in the rock, but it may be very similar to the brown material described in portion A. The surface illustrated on Plate 23, fig. 1, is fairly uniformly covered by the older and dull crust, the crust being slightly scoriaceous. It is characterised to the left of the ridge by a number of shallow depressions. To the right of the ridge there is a fairly deep thumb mark. In striking contrast to this, is the surface illustrated in Plate 23, fig. 2. To the right of the figure, is the round, almost plain surface which joins these two surfaces. This shows flow lines in the crust just above and to the right of the identification number. The rest of the face is covered by a number of depressions separated by sharp well defined ridges. Some of these indentations are very deep as compared with their area, and one is triangular narrow slit half an inch deep. Plate 24, fig. 1 shows the portion resting on the surface first described. At the top is a part of what was once a much larger surface. It is deeply cut into by thumb marks. In the front lower portion the surface is thumb marked on the left, while the remainder forms a broad and deep depression. At the right centre there is a projecting portion with comparatively deep thumb marks. The lower right hand bottom corner is a fresh fracture, while the top right hand corner is occupied by an older fracture now covered with a darker

crust. Plate 24, fig. 2 shows a surface formed by two fractures of different dates. The right hand two-thirds is occupied by an older fracture showing the slickensided portion, while the left one-third is occupied by a fresh fracture, and in this can be seen the light and dark constituents of the meteorite. The two areas can be identified in the figure as they are separated by a well-marked crack Specific gravity 3.728.

Portion E. Plate 26, figs. 1, 2 and 3. Weight 957 kilos. The portion is roughly pyramidal in shape with one face composed of an older fracture, and with one corner slightly cut off by a newer fracture. Its general appearance is so well shown in the figure so that there is no need of describing it any further. The base, fig. 3, is almost flat and covered with a finely granular crust, differing from the crust of the rest of the meteorite.

nation.

Microscopical Exami

The crust is variable in thickness, approximately .02 mm. thick and can generally be divided into three parts, a very thin outer layer, dense black and opaque (.01 mm.), a middle, narrow line of a transparent mineral with high double refraction, and an irregular, much thicker inner layer, partially fused and on its inner side blebby in appearance. It is noticeable that where the angular patches of nickel-iron occur, they project through the two inner layers of the crust and show no sign of fusion or even rounding of their angularities. This is sometimes seen with the silicate minerals. Chondrules abutting on the crust sometimes show a straight edge as if part had been fused off.

Chondrules are fairly common, the number varying from part to part. The commonest chondrules are composed of fibres of enstatite, occasionally radiating, but often set at all angles. The fibres are sometimes separated by a cloudy mineral of low double refraction, the cloudiness being partly due to fine black dust. In two cases the enstatite fibres are associated with a network of an almost black mineral. Often these chondrules are surrounded by a reaction rim of a colourless, highly refracting mineral. Some of the chondrules are almost spherical. A large chondrule (Plate 27, fig. 2), with a well-defined reaction rim is composed of a grey mineral of low double refraction (unidentified) entirely clouded over, partly by fine black dust and partly by decomposition of the mineral.

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