River Stir

The River Stir rises in the Black Mountains and quickly develops into a major river flowing within a deep, wooded valley. For nearly its entire length, it flows through the heart of the Great Forest, fed by many streams and brook. Over 100 yards wide and bridged at only a few points, the river provides a natural and easily defended barrier.

Source

 * Warhammer Fantasy RPG 1st Edition -- pg. 283