Above the sea, are on the Pontotoc ridge in Tippah and Union counties; and from this ridge there is an almost imperceptible slope south and west from the Appalachian Mountain system.
The Pontotoc ridge separates the drainage system of the Mississippi from that of the Tombigbee; extending from the northeastern part of the state southward, this ridge divides in Choctaw county, the eastern branch separating the drainage basin in the Pascagoula from that of the Pearl, and the western branch separating the drainage basin of the Pearl from that of the Big Black and the Mississippi.
Long., and drawn southward and eastward near Ripley, Pontotoc, and Starkville, crossing into Alabama in latitude 32° 45'.
To 100° F.; during nearly the same period at Pontotoc, in the north-eastern part of the state, they ranged from - i 1 ° F.
During the winter the normal temperature decreases quite steadily from south to north; thus the mean temperature in January at Biloxi is 51° F., at Meridian, in the east central part, it is 46° F., and at Pontotoc it is 43° F.