Soil CharacteristicsThe district consists of almost entirely coastal alluvial soil which is suitable for the cultivation of paddy and pulses. Richer black sands are seen East of Kizhavanjiyur in a zone with a maximum width of about 60 meters. Along the coastline light brownish, black and locally pink coloured sands are met with for an average width of about 0.5km on the South of Karaikal. About 82.61 Ha in Karaikal are under brackish water aquaculture and hold a high soil salinity of 25 ppt or more which is unfit for agriculture. Moreover, the coastal sandy soils in Karaikal are highly prone to wind erosion.
Karaikal is an important stratigraphic horizon which indicated the prospects of 'oil shows'. This in turn attracted the attention of the Geological Survey of India between 1959-61 and later on the O.N.G.C., who carried out detailed studies for determining the possibility of the occurrence of oil.
Geological formations :
The Karaikal area is completely covered by a thick mantle of alluvium and no exposures are met with anywhere. The following is the geological succession of the formations :
Mineral Wealth :
The following are the minerals met with in the region :
Brick clays : Brick clays are won from banks of Arasalar about 1.6 km. almost South-West of Pudutturai over an area of 0.6 sq. km. Clayey soils are also employed for making bricks near Melakasakkudi, Nedungadu, Ambagarattur and Vadamattam. Indicated reserves of 1.3 million tonnes have been computed, of which the padugai lands along the Arasalar will account for 0.83 million tonnes.
Kankar : About 0.4 km. in a northerly direction from Melasubbarayapuram village, small amounts of pisolitic kankar are found. It is obtained from a depth of about 1.2 km.
Sea Shells : Sea-shells collected from the coast are made use of in making lime for local use. Lime kilns were observed to the West of Karaikal town, near T.R.Pattinam and Akkaravattam.
Ilmenite and garnet sands : Ilmenite and garnet sands occur in varying concentrations in the beach sands along the Karaikal coast over a stretch of about 10 km. and varying in width from 20 to 100 m.
Oil : It may not be out of place to mention about the prospecting for oil going on in the area, as a result of the favourable structures and thick sediments deciphered first by the geophysical division of the Geological Survey of India, and later on by the Oil and Natural Gas Commission.