The Vindhyan system of rocks brings the purana Era in the Geology of India to a close as the basins that received the sediments of those times got silted up and no fresh basin came into existence for a long time after that to receive the sediments of succeeding period. With the commencement of the new era called the Dravidian era, the extrapeninsula underwent movements of subsidence and develooed marine conditions in certain restricted areas.

The geological formations developed during the palaeozoic Era are generally found to contain fossils Therefore, in this respect, these rocks differ radically from the unfossiliferous formations of Pre-cambrian and Archaean ages.

Palaeozoic rocks formed under marine environment and containing distinct remains of organisms are developed characteristi­cally in the extra-peninsula. In the peninsula, the palaeozoic group is represented by:

(i) Talchir and Damuda series of Permo-carboniferous age.

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(ii) The marine lower permian rocks near Umaria in M

(iii) A portion of the Vindhyan sequence which is possibly of Cambrian age.

Salt Range . [West Pakistan].

In this area, the sequence commences with Cambrian-rocks’ and so far no distinct pre-cambrian rock has been found to form the basement. Cambrian rocks overlain directly by the glacial boulder beds of Up. carboniferous age.

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Fauna:

Trilobites, Brachiopods, Foraminifeia, Sponges, Echinoderms, Gastropods and Pelecypods.

The saline series is made up of salt marls. They are devoid bedding planes. The top part contains, gypsum dolomite and oil shale and also altered lava flows known as Khewra trap. Massive gypsum are called ‘Kalabagh Diamonds’. The age of the saline series is still controversial.

Palaeozoic of Kashmir:

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A complete succession of palaeozoic rocks exist in Kashmir/and adjacent areas and appear to have been folded conspicuously in the form of synclines and anticlines. The cambrian fauna of Kashmir differs from that of the Salt range and Spiti areas.

In Hazara area, unfossiliferous palaeozoic rocks made up of conglomerates, quartzites, phyllites etc, together form what is known as Tanwal series. It may range in age from cambrian to Up. carboniferous. It is overlain by the glacial Tanakki conglomerates of Permo-carboniferous age.

Spiti :

The Haimanta system of Spiti overlies the Vaikrita system of Pre cambrian age. The lower Haimantas are greenish phyllites, shales and thick bedded quartzites. The Mid. Haimantas are red and pink quartzites and shales. The Up. Haimantas, also known as Parahio series, are mainly grey and green quartzites, slates, shales with thin beds of grey dolomites.

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In Kumaon the Haimantas are represented by Garbyang series consists of slaty to phyllitic,’ finegrained sandstone, calcareous sandstone and argillaceous dolomite.