Short essay on The Cuddapah System

The Cuddapah represents a parallel series of ancient sedimentary strata assuming a thickness of about 6000 meters. The name has been derived after Cuddapah District of Andhra Pradesh where these rocks occur in a semi-circular basin covering about 35,100 square km. of the state's area (Cuddapah and Kumool districts).

These rocks were deposited from Cambrian period to pre-Algonikan period in the Cuddapah depression, die Godavari graven, and probably die major parts of the Narmada-Son- Damodar graven. The N-S-D graven and the north­western part of the Godavari graven form part of the Deccan syneclise. Both these grabbers appear to have originated during the Cuddapah times. The Cuddapah rocks include shale, slate, quartzite and limestone. These rocks have been greatly metamorphosed and lack in fossils. The Cuddapah system consists of two rock-formations: (a) lowerCuddapah, and (b) upper Cuddapah.

Lithology

The principal rocks of the Cuddapah system are the quartzite's, indurated sandstones, slates, shales and limestones with banded jaspers. The quartzites are metamorphosed sandstones, while shale's have acquired slaty cleavage. Lava and tuff beds are also present in these rocks indicating some igneous activ­ity during the period. The lower Cuddapahs contain coloured and banded cherts and jaspers and some interstratified iron and manganese ores, very much like those of the Dharwar system. But the upper

Cuddapahs consisting of unmetamorphosed shales and limestone's, show close resemblance to the over­lying Vindhyan system. Except in the Yellaconda range of the Eastern Ghats the Cuddapah rocks arc generally horizontal. The enormous thicknesses of these rocks indicate the sinking beds of the basins with the growing sedimentation.

Distribution

There are four main areas of occurrence to the Cuddapah rocks : (i) Cuddapah and Kurnool dis­tricts of Andhra Pradesh, (ii) the Chhattisgarh region of Chhattisgarh, (iii) Rajasthan-Delhi region, and (iv) the Lesser Himalayas in the extra Peninsula.

(i) The Cuddapah Region

The Cuddapah system, developed in the typi­cal Cuddapah basin, is divided into two sections (lowerand upper) and four main series (Table 2.III). Srisailum quartzites Kolumnala slate Irlakonda quartzite Upper Cuddapah.

Unconformity

Papaghani Series-the series is named after the Papaghani River in whose valley its rocks have been exposed. It consists of quartzites (Gulcheru quartzite), sandstones (in the lower part), shales, slates (Vaimpalli slates), limestones and marbles (in the upper part). The series is intruded by magma in the form of dykes and sills which has metamor­phosed limestone into marble, serpentine and talc. Slates, limestones and basalts are important because of the occurrence of deposits of barytes and asbestos.

Cheyair Series-It lies in the valley of the Cheyair river and consists of two stages, the lower called the Nagri composed of quartzites and the upper Pullempet made of slates.

Nallamalai Series-The series derives its name from the Nallamalai hills where it is exposed. Its component rocks are quartzites (Barrenkondaquartz- ite) in the lower part, and indurated shales and slates (Cumbum slates) in the upper part. The limestones interstratified with the shales contain deposits of lead and galena.

Kistna Series-this is the youngest and the upper most series of the Cuddapah system which occupies the part of the Krishna valley. It consists of quartzites (Irlakonda quartzite) in the lower part, slates (Kolumnala slate) in the middle part and quartzites (Srisaillum quartzites) in the upper part. A zone of unconformity separates this series from the overlying lower Vindhyan rocks.

(ii) Madhya Pradesh, Orissa and Maharashtra

The Cuddapah system of rocks in Madhya Pradesh, Orissa and Maharashtra has many out­crops which consist of following main series.

Bijawar Series-it occupies parts of Chhatarpur and Panna districts of Madhya Pradesh. It is com­posed of sandstones and quartzites at the base overlain by limestones and ferruginous sandstones. It has basaltic intrusions whose dykes are rich in dia­monds.

Gwalior Series-The Cuddapah system of rocks found in the vicinity of Gwalior is called Gwalior series which largely consists of sandstones, shales and quartzites overlain by shales, limestones, hornstones, jaspers and basaltic lavas of the Bijapur type. The lower part of this series is called Par and the upper as the Morar series. Dr. Heron considers the Gwalior series as an isolated outcrop of unmetamorphosed Aravalli series (Wadia, 1975, p. 118).

Rajpur Series-this series belongs to the Upper Cuddapah and occupies a large area in the upper Mahanadi valley in Durg, Rajpur, Bilaspur (Chhattisgarh) and Sambalpur (Orissa) districts. It consits of shales and limestone's.

Kaldgi Series-It lies in Bijapur district of Maharashtra between the towns of Belgaum and

Kaladgi. Its upper parts are highly ferruginous and yields iron ore.

Pakhal Series-It occurs in the Godavari val­ley and consists of rocks like quartzite's, shale's and flinty limestone. Similar rocks in the valley of the Pranhita are called the Penganga beds.

(iii) Rajasthan and Delhi Region

The Cuddapah rocks in Rajasthan and Delhi are designated as the Delhi system which covers a large area from Idar to Delhi. It overlies the Raialo series, the youngest of the archaeans. It largely consists of quartzite's, slates, grits and flagstones. The system is intruded by granite bosses and laccolites with their related group of pegmatites and aplites {Erinpura granite). Its outcrops are found at Ajmer, Alwar and Bharatpur. Dr. A.M. Heron has classified the Delhi system as follows:

Raialo series (Archaean), limestone, mar­ble, quartzites Malani Series-The granitic intrusions in the Delhi system in the central and southern Rajasthan are called the Erinpura granite and in western Rajasthan as the Malani series. The Malani series consist of granites (Jalor and Siwana granites) and rhyolites (Malani rhyolites).

(iv) Extra-Peninsular Region

Outcrops of the Cuddapah system are also noticed in Kashmir, Shimla and the Nepal Himala­yas in which slates ^nd quartzites are the main rocks.

The deposits of slates, with flaggy quartzites, in southern part of Pirpanjal, Ramban and Kishtwar areas are called the Dogra slates (after Dogra Rajputs inhabiting the region) which are used as building material for roofing and flooring. Similarly in the Shimla Himalayas the slates are designated as the Shimla system.

Life

The Cuddapah rocks are azoic or unfossiliferous although limestones and shales are well suited for the preservation of organic remains. Either life did not exist during the Cuddapah times or early organisms did not have hard parts in their body to preserve as fossils.

Economics

The Cuddapah rocks contain iron and manga­nese ores, barytes and asbestos (Papaghanis), cop­per, nickel and cobalt (Delhi system). They also provide slates, marble, steatite and jaspers which are used as building material in house construction and interior decoration.