The word "prairie" means properly an open level country, though it is not necessary that it should be a _dead horizontal_ level, to entitle it to the name.

It may contain hills, valleys, and long ridges.

It is not necessary either that it should be entirely destitute of trees; for there are the "timber prairies," where trees grow in "mottes" or groves, sometimes termed islands--from their resemblance to wooded islands in the sea.

The "prairie" is a term used to distinguish those vast meadow-like tracts of the earth's surface from the forest, the mountain, and the ocean.

The prairies themselves are distinguished by specific names, according to what covers their surface.