Plant fossils from Terani clay bed

January 3rd, 2016

Riffin

The Upper Gondwana sediments known as “Sivaganga Formation”, represents the first phase of sedimentation in the Cauvery basin. Outcrops are scanty and isolated due to alluvial cover, rarely exceeds 2km in width and at places less than 50m. The upper Gondwana in Tiruchirapalli area is divisible into two formations – the lower Boulder Conglomerate – Sandstone and the upper Terani Clay.
The lower unit is well exposed at Kovandakurichchi quarry, also about 1.5km ENE of Uttatur; and 1.5km NE of Terani and Karai. It is a clast supported framework, some of the clasts exceeding one metre in diameter, comprising of pink, buff colored feldspar, quartz mostly sub-angular to sub-rounded, boulders, cobbles and pebbles of Archean gneissic basement suite; inverse graded bedding (coarsening up) is conspicuous at Kovandakurichchi quarry, Dalmiapuram. This member rests on the Archean Crystallines and grades upward gradually into ferruginous gritty sandstone, siltstone with clay towards the top (Teranipalayam).
The upper unit is known as “Terani Clay beds”. These clays are dirty white, yellowish brown, thin to thick bedded with intervening medium to coarse grained friable, limonitic/ferruginous sandstones with parallel bedding. At places show sharp planar to erosive bases and faulted contacts. Clays are very soft, soapy, 6” to 2’ thick, rich in plant fossils. The plant fossils are represented by several families such as
i) Filicates – Cladophlebis indica, Actinopteris;
ii) Cycadophyta – Ptillophyllum acutifolicum iii) Coniferals-Elatocladus fonferta etc.

Courtesy: Field Visit page of International conference on geo science and environment,January-2016

Key: Terani,WFS,Riffin T Sajeev,Russel T sajeev,World Fossil Society