222 A. E. PARKINS 



vious one. This seems to be the way in which the cliff in Fig. 3 

 was produced. 



From a study of the ten or twelve valleys examined I think it 

 is possible to make the general statements: that valleys of inter- 

 mittent streams which head in cultivated fields are generally flat 

 floored due to filling; that the filling is intermittent, being affected 

 by kinds of crops, and wet and dry periods; that such valleys are 

 usually characterized by steps; and that these steps are first 

 caused by dams of stones and brush, and may become higher by 

 recession. In all such valleys we have an interruption in the 

 normal cycle of erosion, caused by an increase in the supply of 

 waste brought to the headwaters ; and when this supply is decreased 

 the stream will clear away the waste and erosion will go on agree- 

 able to the normal order. 



