uppermost throughout Bhadráchalam, Chódavaram and the eastern portion of Pólavaram, and, in the form of what is called Bezwáda gneiss, throughout Yellavaram and much of Tuni as well as in the north of Rajahmundry and Peddápuram taluks.
After the gneiss, the next most ancient formation is three groups of the Lower Gondwána rocks. The Tálchir group is found in very small and scattered tracts in the Nizam's Dominions and also near Dummagúdem, between Dummagúdem and Bhadráchalam, and between Bhadráchalam and Rékapalle; the Kámthi group stretches all along the river on the Hyderabad side, but only reaches into this district at the south-western corner of the Pólavaram division; and the Barákar group occurs in small and scattered areas in two places in the district, namely Bedadanúru in the south-west corner of Pólavaram, and Gauridévipéta sixteen miles down the river from Bhadráchalam. This group is of particular interest, because coal is found in it.*[1]
Among still more recent geological formations, a few small outcrops of the older Tirupati sandstones occur between the gneiss and the alluvium of Peddápuram and Tuni. A broad belt of the Cuddalore sandstone also stretches, like an island in the middle of the alluvium, from Rajahmundry to Samalkot with a narrow strip of Deccan trap and some isolated patches of gneiss on its north-western edge. The whole of the rest of the district is formed of fluviatile alluvium. This occupies nearly the whole of the delta, and above the gháts stretches in some places a long way from the river on either side.
At some remote period the great plain which is now covered with alluvial soils must have been occupied by the sea, the sandstone 'island' between Rajahmundry and Samalkot must have been an island in fact, and the salt water must have stretched to the edge of the northern hills. This plain was gradually raised above tidal level by the deltaic deposits of the Gôdávari and the minor streams in the north-east of the district, and the process still continues. It is particularly noticeable in the constant extension of the shore round Point Gódávari and the gradual silting up of Coringa bay. In Pliny's time the village of Coringa, now miles inland, stood apparently upon a cape, and even within the memory of man great changes have taken place. The map of 1842 had to be much modified in 1891 and already needs further alteration. A spit of land is extending to the north from the old Point Gódávari at an estimated rate of one
- ↑ * See below p. 10.
