to the Ille or the Vilaine from all around the large basin of Rennes. The elevated hills bordering this basin are covered by several old forests now exploited by men for the production of wood. The basin itself is a rich agriculture area, as well as the north-west of the department near the Rance.

In the extreme south of the department the Vilaine goes through a slower decrease in elevation in a small corridor in the area of the city of Redon; in this area, the Vilaine is known for its frequent floods during