The principal rivers are: the Mississippi on the western border, and its tributaries, the Yazoo and the Big Black; the Pearl and Pascagoula, which drain much of the southern portion of the state and flow into the Gulf; and the Tombigbee, which drains most of the north-eastern portion.
The Delta is drained chiefly by the Yazoo.
Deposits of the Tertiary period form the basis of more than half the state, extending from the border of the Cretaceous westward nearly to the Yazoo Delta and the Mississippi Bottom, and southward to within a few miles of the Gulf coast.
of the Gulf coast, and, with alluvium, in the Yazoo Delta.
at several places in the southern part of the state, and at Yazoo city, in the west central part, it is 83° F.