RIVER EROSION 158 
Where the soil is a clay, it may be cut into very 
remarkable and fantastic columns by the. action of 
rain erosion (Fig. 77). This is particularly true in 
arid regions, as in the Bad Lands of South Dakota, 
and many other parts of the West (Plate 4). These 
Fic. 77. 
Earth columns in New Mexico. Caused by rain-sculpturing of clay beds. 
rain-carved columns are often capped and protected by 
hard fragments, which allow them to stand up to a 
height of several score of feet, even though they are 
composed of a soft clay. Every rain, though these are 
rare in the dry country of the West, sculptures the 
clay a little more. The scenery in these rain-sculpt- 
