It was so deep that, in riding along it, the heads of our travellers were on a level with the prairie.

It had been thus hollowed out by the water during heavy rains, as the soil, previously loosened by the hoofs of the buffaloes, was then carried off to the rivers.

Such roads the buffaloes follow at times, thousands of them keeping in the same trail.

They travel thus when they are migrating in search of better pastures, or water--to which they know by experience the roads will conduct them.
Our hunters did not follow this road far, as there was no certainty that it would bring them to where the animals then were.

They crossed over, and kept on for the butte.
"_Voila_!" cried Francois, "what are these ?" Francois pointed to several circular hollows that appeared in the prairie before them.
"Buffalo-wallows, I declare!" said Basil: "some of them are quite fresh too!" "Buffalo-wallows!" echoed Francois; "what are they ?" "Why, have you never heard of them, Frank ?" asked Basil.