Early in the afternoon they had entered upon a strange tract, over which the road of the buffaloes led them.

It was a part of the prairie--a series of low hills composed of pure gypsum.

These extended around them, as far as our travellers could see, presenting on all sides a picture of alabaster whiteness.

Neither plant, nor tree, nor any sign of vegetable life relieved the monotonous uniformity of the landscape.

Turn to what side they might, their eyes were met by the lime-like surface of hill and dale, dazzling the sight with its milky whiteness.