sod, but with no standing water. The well-developed sod is a condition that causes the vegetation of the valleys to be quite distinct in appearance from that of the uplands, with the tufted appearance of the bunch grass association. Such dry valleys are very common throughout the southern portion of the Sand Hills. They yield an abundant crop of

Fig. 11. A Deep Blow-out; Redfieldia on the slopes.

fine hay during moist seasons and always afford very fine forage because of the presence of buffalo grass (Bulbilis dactyloides), and grama grass (Bouteloua oligostachya) in considerable quantity. The soil of these valleys is not so sandy as the uplands. This with the water table nearer the surface makes possible the culture of certain agricultural crops, if the proper care is taken to prevent the soil from blowing. When the sod is broken in a dry valley where a considerable area of nearly flat soil