1821 H. E. Lloyd tr. M. von Engelhardt in tr. O. von Kotzebue III. App. 343 As the one coast (the Asiatic) is said to be steep, the opposite one flat, they are to each as the banks of a river and side valleys, forming by running waters.
1869 H. F. Tozer I. 299 At last we struck up a side valley.
2011 Y. Brauen 35 The nomads..hid in a side valley until they heard the soldiers had left the area.