noon
As we got farther among the sand dunes we found them all sizes and shapes , though usually circular , and from fifteen to forty feet high . Of course the surface of the county was very irregular , and there would be places here and there where the grass had obtained a little footing and the sand had not drifted up . There were also some hills which seemed to be independent of the sand piles . We stopped for noon on a little flat where there was some struggling grass , This flat ran off to the north , and narrowed into a small valley through which in the spring probably a little water flowed . We had finished dinner when we noticed a flock of big birds circling about the little valley , and , on looking closer , saw that some of them were on the ground . `` They are sand-hill cranes , '' said Jack . `` I 've seen them in Dakota , but this must be their home . ''