After they had crossed the ford of the Big Blue--a hundred yards of racing water--they passed what is now the line between Kansas and Nebraska, and followed up the Little Blue, beyond whose ford the trail left these quieter river valleys and headed out over a high table-land in a keen straight flight over the great valley of the Platte, the highway to the Rockies.
Now the soil was sandier; the grass changed yet again.

They had rolled under wheel by now more than one hundred different varieties of wild grasses.

The vegetation began to show the growing altitude.

The cactus was seen now and then.

On the far horizon the wavering mysteries of the mirage appeared, marvelous in deceptiveness, mystical, alluring, the very spirits of the Far West, appearing to move before their eyes in giant pantomime.