"Geology of Tamil Nadu Tamil Nadu represents an important high grade metamorphic terrain of global importance. Geologically, state is divided into three regions viz., the Central region, the Northern region and the Southern region. Central Region The central region divides the North and South by a comparatively smaller East-West zone which is about 50 km wide.The central region is marked by two prominent tectonic zones viz., East-West trending Moyar-Bhavani-Attur (MBA)on the North and Palghat- Noyyil-Cauvery (PNC)in the south. They are largely made up of reworked gneisses carrying enclaves of older schists, amphibolites, Fuchsite quartzite, Banded magnetite quartzite, calc- granulites with limestone, and layered Anorthosite complex (Bhavani layered complex and Sittampundi complex). Dolerites are comparatively less in this zone and are exposed with many younger granites of Proterozoic age. Northern Region Northern region is occupied by the amphibolites facies terrain which is the southern extension of Dharwar craton. There is a transitional zone extending from Mangalore to Chennai that separates the amphibolites terrain from the predominantly Charnockite terrain of Chennai-Thiruvallur, Javadi, Shevaroy Hills, Chitteri and Kalrayan massifs. The major basicoccurrence in the North zone is the amphibolites in Vepanapalli-Maharajagadai area which is the southern extension of the Kolar (Gold-bearing) schist belt that forms the Kolar group of rocks. There are many Banded Magnetite Quartzites (BMQ)which run to the extent of few hundred metres in length, noticed throughout the northern Tamil Nadu of which the major ones are the Kavuthimalai, Vediyappanmalai, Kanjamalai and Thirthamalai. The intrusion of swarms of dolerite and dykes is concentrated in Sholingar–Gudiyattam–Krishnagiri belt. Southern Region It occurs to the south of the Palghat-Cauvery tectonic zone. On the west of this zone, chromites form the massifs of the Western Ghats and the Eastern part is predominantly made of gneisses. This region differs from the Northern and Central regions by the predominance 1 of meta-sedimentary rocks such as quartzites, sillimanite quartzites, calc-granulites, garnet and cordierite bearing meta-pelites. This zone is totally devoid of dolerite dykes and banded magnetite quartzites. In the Northern part of this region calc-silicates and crystalline limestone occur as thick sequences for a few tens of metres thickness. Extensive limestone deposits are found from Palayam to Kiranur, Rajapalayam-Alangulam belt east of Varshanad hills and Talaiyuthu near Tirunelveli. At the southern extremity of peninsular India and to the south of the Achankoil shear zone consist of garnet-biotitic-graphite gneisses and garnetiferous charnockite and khondalites (garnet-sillimanite-biotitic-graphite), cordierite gneiss. 1 (Geology)Meta-sedementary rocksare sediments or sedimentary rocks which show evidence of metamorphism. (Pedology)Meta- sedmentary rocks are metamorphic rocks formed from sedimentary rocks. McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, (2003)The McGraw-Hill Companies, Inc."