| Geology |
 |
Most of the area is covered by the unconsolidated sediments of Quaternary age except in the northwestern part, where isolated patches of Archaen Crystallines and Tertiary sandstone are exposed. The Archaeans are mainly represented by the Charnockite Group of rocks comprising garnetiferrous granulite and the Khondalite Group of rocks made up of quartzite of genesses. The Tertiary sandstone (Cuddalore Formation) comprise pinkish, yellowish, reddish (variegated colours) medium to coarse grained sandstone and clay stone. It is overlain by thin alluvium and exposed towards north of Vaigai River. Detached exposures of laterite and lateritic soil are seen in the northwestern part of the district. A major part of the district is covered with the fluvial, fuvio-marine, Aeolian and marine sediments of Quaternary age. The fluvial deposits which are made up of sand, silt and clay in varying degree |
of admixture
occur along the active channels of Vaigai, Gundar, Manimuthar
and Pambar rivers. They have been categorized into levee, flood
basin, channel bar/ point bar and paleo-channel deposits. The
paleo channel deposits comprise brown coloured, fine to medium
sands with well preserved cross-beddings. |
The fluvio-marine deposits are exposed in the Vaigai delta as deltaic plain, paleo-tidal and dune flat deposits. The deltaic plain and dune flats comprise medium, Grey brown sands. The paleo tidal flat deposits include black silty clay, black clay and mud. In Rameswaram Island, the fluvio-marine deposits include indurated sand and dune sands. The Aeolian deposits comprise red sands which are in nature of ancient dunes and occur over a 3.2 Km wide and 8 Km long stretch and lie parallel to the sea coast. These are separated by marshy deposits of black clays. The sands are underlain by calcareous hardpan. In Rameswaram Island also brown sand deposits occur around Sambaimadam on either side of NH 49 west of the town.
The marine formation comprises coastal plain deposits of sand and clay in varied proportion. Marine calcareous hardpan occurs as low terraces and platforms, with admixture of quartz, limonite and garnet concentration.
| Agriculture |
Paddy
In Ramanathapuram District, paddy is main food crop cultivated in more than 63% of the net area sown. It is cultivated both as irrigated and rainfed. Rainfed sowing generally commences from August and will extend upto October. In early sown area, farmers used to raise medium and long duration varieties of paddy. There is no marked area for late sowing, but when the monsoon rains delayed, the sowing will be also taken up late. In the late sown areas medium and short duration paddy varieties are sown. Farmers are having 10 local paddy varieties in addition to high yielding varieties with the duration ranging from 105-130 days and they will choose varieties according to the need based. Redgram is sown as a mixed crop with rainfed areas and also grown in garden lands to a limited extent. In tankfed ayacut area Irrigated paddy is sown generally in August to November. Sometimes sowing will be further extended upto December according to the filling of rainwater in the tanks and also release of water from Vaigai Dam to the Vaigai fed system tanks.
Cholam
Rainfed Cholam sowing is taken up in dry lands between July to September. Beyond September there would not be any sowing of Cholam crop and Cumbu crop will be sown as alternate crop in these areas. Lablab pulses is also sown as mixed crop.
Cumbu
Rainfed Cumbu sowing is generally taken up between September to November. Only in Ramanathapuram Taluk the sowing will be extended upto December. Irrigated Cumbu is taken up from February, March to June, July.
Ragi
Rainfed Ragi sowing is taken up during September and October. Irrigated Ragi is mainly sown in September to October in East Ramanathapuram where the crop is sown in tankfed ayacut.
Minor millets
Minor millets are generally sown between July to November and the area is spreaded over throughout the district.
Cotton
Rainfed cotton sowing is taken up in September-October. The sowing will be extended sometimes upto December depending upon rainfall. Rice fallow cotton is generally sown in Paramakudi and Kamuthi taluks during January-February months.
Pluses
Redgram is sown in June to August. Blackgram, Greengram and Cowpea are sown as rainfed crop in September, October months. Redgram is sown as mixed crop with millets and groundnut. Blackgram and Greengram are sown as pure crop as well as mixed crop in cotton and sugarcane. The Cowpea is sown as pure crop and also in some places as mixed crop with millets.
Groundnut and Gingely
Groundnut and Gingely are cultivated mostly in Rainfed condition, during the month of December-January and April – May.
Chillies
Chillies are cultivated in both rainfed and irrigated condition. Chillies are directly broadcasted in the month of September. The transplanted chillies will be taken in the fortnight of November.