From an by the authors in the adjoining western sheet 46J/2,6. examination of a collection of echinoids from the Bagh beds Fourtau1 assigned an Albian age to the fauna. The results of recent researches of Von Heune and Matley2 on the Dinosaurian remains in the Lametas of Jabalpur and Pisdura in the Central Provinces, definitely fix the age of the Lametas, the fresh water equivalents of the Bagh beds, as ranging in age from the Turonian to Upper Senonian. A general review of previous works shows therefore that from a study of their contained echinoid fauna, the Bagh beds of the type area were regarded as Cenomanian by Duncan, which was subsequently confirmed by Vredenburg on the evidence of the ammonite fauna. The results of recent investigations on the Bagh fossil fauna from the Jhabua and Ali Rajpur States, which has been found to contain several typical South Indian Upper Cretaceous forms, namely, Protocardium pondicherriense, Cardium (Trachycardium) incomptum, Macrocallista cf. sculpturata, Turritella (Zaria) multistriata, suggest that the Bagh fauna probably ranges up to Upper Senonian. The presence of characteristic Utatur forms in the Bagh fauna, namely, Grotriana cf. jugosa and Crassinella cf. planissima, shows that the beds range down to the Cenomanian. The probable age of the Bagh beds, as established from the examination of the Bagh fauna, appears to be Cenomanian to Upper Senonian. The Nimar sandstone. Gritty sandstone, corresponding, both in its lithology and mode of occurrence with the Nimar sandstone of P. N. Bose3, has been recorded south-east of Pavagarh Hill (22° 26': Pavagarh Hill. 73° 32'). The sandstone unconformably overlies the Aravalli schists and phyllites and is overlain by the Deccan trap. The formation is almost horizontal and is composed of pinkish sandstone with porcellanic jasperoid rock, associated with ferruginous conglomeratic beds containing pebbles of quartz and chalcedony. No fossils have been found in it. The grit is extensively used as building stone, especially in the ruined city of Champaner, the capital of the old Mahommedan Kingdom of Gujarat. Small patchy outcrops of these gritty sandstones, associated with conglomeratic beds, occur north of Bhamria (22° 24′ : 73° 36′). 1 Rec. Geol. Surv. Ind., XLIX, pt. I, (1918). 2 Pal. Ind., New Ser., XXI, Mem. I, (1933). Distribution. THE DECCAN TRAP. A profusion of dark grey basalt, the Deccan trap lava flows, covers an extensive area along the eastern margin of the area under description. Several outliers of the trap are also seen in the central tracts of the area, mainly occupied by the Aravalli schists and phyllites. Innumerable detached outliers of the Deccan trap have also been recorded on the alluvial plains in the west of the area. All over the eastern area, the Deccan trap is generally massive or finely crystalline and almost, as a rule, non-vesicular. It wea Lithology. thers into rounded, dark boulders and gravels, and finally yields black, highly fertile soil. The rock is characterised by general homogeneity of composition and compactness of texture. Felspars, generally occurring as small laths, augite and opaque grains of iron ores are the constituent minerals. The Deccan trap in the central area, occurring along the western frontiers of the Dohad and Jhalod talukas of the Panch Mahals district, is generally fine-grained and compact. More or less porphyritic types have also been occasionally noted. No vesicular nor amygdaloidal types have been seen in the field. Under the microscope the finer type shows (44/136; 22080) a finely crystalline texture. Felspars in small laths, augite and opaque iron ores are the constituents. Fairly large felspar phenocrysts have been seen to occur in the porphyritic type of the basalt. Under the microscope the rock (44/137; 22081) shows tabular phenocrysts, as well as well-defined laths of plagioclase felspars, with polysynthetic twinning after the albite law, the tabular patches showing broad lamellæ. The pyroxene occurs as small prisms, and is mostly nonpleochroic. The average extinction angle is about 45°. This mineral is often partly replaced by alteration products, both chloritic and serpentinous materials. Iron ores are present in grains and blotches. Patches of glassy base are also noticeable in the thin section. These vary in colour from brownish opaque to more or less clear yellow and show weak double refraction, possibly due to devitrification. Of the numerous outcrops of the Deccan trap in the alluvial plains of the west, those occurring at the western frontiers of Lunavada and Balasinor States may be taken as representative. The rock is characterised by general homogeneity of composition and : compactness of texture. Slightly vesicular instances have, however, been occasionally noticed. Near Hothwad (23° 1' 73° 17') the vesicular cavities in the trap have been found to be filled with calcite and zeolites, mostly stilbite (46/515). The basalt is generally holocrystalline and is composed of plagioclase felspar, mostly labradorite, occurring as small laths, granular or platy pyroxene and grains of opaque iron ore. The rock is dark in colour and weathers into brownish and greenish boulders and gravel. These finally yield the dark, highly fertile, black cotton soil. The lava heaps west of Hothwad (23° 1′; 73° 17′) often contain a somewhat porphyritic type. (46/516). Under the microscope it shows porphyritic olivine. much traversed by cracks filled with green serpentinous decomposition products, greenish non-pleochroic pyroxene, often showing imperfect cleavage traces, and small laths and needles of plagioclase felspar. Spots of magnetite and small patches of chlorite also occur in fair abundance. The rock is a typical olivine-basalt. No intertrappean beds have been noticed anywhere in the area under review, and it has not been possible to divide up the Deccan trap into distinct individual flows, nor to gain any information as to its age, except that it is post-Cretaceous. Laterite. POST-TERTIARY DEPOSITS. Several instances of lateritic cappings on the trap have been noticed. These are irregular in their occurrence and do not show any considerable thickness. The laterite is indefinite in its composition, the limonitic and aluminous ingredients ever varying. In colour it varies from light red to dark brown. Nodular, concretionary calcium carbonate is often met with in the soil on the crystalline areas adjoining the trap. The nodules owe their origin mainly to the calcareous solutions derived from the decomposition of trap. Kankar. Soil. Dark grey cotton soil covers the elevated plains adjoining the trap mounds and ridges. It is extremely fertile and prosperous agricultural villages flourish on it. Over the metamorphic regions the alluvial mantle varies widely in thickness. The richness of the soil is also variable. The granite and gneisses on disintegration yield rather poor sandy soil. The crumbling schists, on the other hand, are invariably covered with fertile soil derived from their own disintegration and support rich vegetation. ECONOMIC RESOURCES. Bauxite. A rich deposit of bauxite has been recorded near Taibpur (23° 2' : 73° 4′) in the Kapadvanj taluka of Kaira district in association with the Ahmednagar sandstone. This deposit of bauxite was formerly worked by Messrs. Killick Nixon and Co., of Bombay, Managing Agents of the Shivrajpur Mines Syndicate, who have stopped the work temporarily. Limestone. Building materials. Generally the Aravalli limestones of the area are too much broken and ramified with secondary siliceous veins to be of any use as a building stone. The thick bands of limestone at the northern frontier of Jambughoda State (Narukot) contain small patches of crystalline marbles. Both white and tinted varieties occur. These should make a useful building stone. The slabby calcareous bands occurring in the infratrappeans of Alirajpur, Jhabua, Lunavada and the small Mahi Kantha States are often quite suitable for building purposes. The sandy bands in the infratrappeans are often excavated for building purposes, as well as for the manufacture of grindstones. Sandstone. Slate. Extensive occurrences of slate have been seen in the argillaceous metamorphics of the Aravalli system. The most noteworthy occurrences are in the Jhalod taluka of the Panch Mahals district. The rock has developed jointing and yields slabs of varying sizes in abundance. Slabs measuring up to 12 feet by 4 feet have been noticed. The thickness varies between three and six inches. Tiles of irregular size and varying thickness are also available in the area. Fire-clay. Fire-clay has been recorded near Derol railway station, (22° 38′ : 73° 28') Panch Mahals district, in association with infratrappean The clay is refractory at 1,400°C. and does not shrink Its plasticity is rather poor. The occurrence is confined to a small area. sandstones. on firing. Galena. A deposit of galena has been recorded near Khandia (22° 19′ : 73° 33') in the Bhamria State, in the Aravalli phyllites and schists. The ore-body occurs in irregular thin veins and stringers intimately associated with quartz-veins intruding the schists. The irregularly ienticular occurrence and soil-covered condition of a considerable portion of the metalliferous zone render it difficult to be definite about the prospects of the deposit. A specimen of galena from the quartz-galena lode assayed in the Geological Survey Laboratory gave 18-16 oz. of silver per long ton. Iron-ores. Iron-ores have been recorded in Jambughoda State in the hematitequartzite hills about 1 miles south-west of Jambughoda (22° 22′ : 73° 44′). Specular iron-ore occurs in association with phyllites and quartzite around Jambughoda. These occurrences are not of economic potentiality, the deposits being small. Manganese-ores. Manganese-ore bodies of varying size and potentiality have been known to occur in the southern tracts of the Panch Mahals district as well as in the Jhabua State of the Central India Agency and the Chhota Udepur and the Narukot States of the Rewa Kantha States Agency. These invariably occur in association with the ancient metamorphics, the Aravalli schists and quartzites of the area, as irregular nests and lenticular bodies. The most important of these deposits are those worked at Kajlidongri, Shivrajpur and Pani mines. Of the manganese occurrences in Jhabua the two deposits of considerable economic importance, namely the Kajlidongri and the Rambhapur deposits, were examined by Sir L. L. Fermor in 1905, and several other deposits were subsequently reported upon by Mr. H. Walker and Dr. A. M. Heron in 1907. Jhabua State. |