A vast marine graveyard dating back millions of years to the Cretaceous era and the first markers of the wealth of natural history in this area that is spread across at least four districts — Ariyalur, Perambalur, Tiruchi and Cuddalore.

  • The fossil of Ariyalur site is spread out over 2 lakh acres within a 40-70 kilometre radius from Ariyalur town.
  • It covers Samayapuram and Kallakudi in Tiruchi district, Sathanur in Perambalur district and the coastal region close to Marakkanam in Cuddalore district.
  • The mouth of the Vellar was considered the entry point of the sea from the Bay of Bengal (a phenomenon called sea ingression).
  • After being a marine haven for 40 million years, the sea evaporated (known as regression), leaving behind a vast graveyard of shellfish, corals, clams, gastropods and branchiopods.
  • These formed huge bands of sedimentary rocks, most of it limestone, the main raw material for cement production.
  • The region is a magnet for cement companies because of the purity of Ariyalur’s limestone (90% compared to the 67% required for production).
  • The factories burn a mixture of powdered limestone, gypsum, coal and other chemicals to produce cement and clinker (a stony residue).
  • But unchecked mining has led to air pollution and large quantities of overburden soil being heaped up randomly.
  • The rock structure of this area can be divided into four zones or stages: Uttathur, Trichinopoly, Ariyalur and Ninniyur, with Uttathur being the oldest.
  • “Every era of 1000 years can be seen as clearly as a booklet on the rock formations.
  • When it rains, the top soil is eroded, and soft rock below it is left behind.
  • After comparing the age and colour of the rock formations here with those of the Himalayas, we have found that that they are of the same age