THE RIVER GORGE. 51 



some extent. The making of the planet has been merely a 

 progressive changing of the fashion of the materials of which 

 it is composed. If the completed planet as we see it is the 

 product of geological forces, then the work of sedimentation 

 proceeds by means of forces which are geological. The least 

 mentionable portion of that work is performed by such force. 

 The filling of boyhood's mill-pond was a geological work. 

 The slime settled by the roadside is a geological phenomenon. 

 These are results accomplished; let us see how far we can 

 trace them to their causes, and thus unfold a bit of the 

 world's history. 



The sediments have been brought by moving waters ; we 

 must therefore trace the waters to their sources ; we must re- 

 trace their course from the higher level. Obviously, the 

 roadside slime has descended the rill-ways from the middle of 

 the street ; from the hill-slope down which a portion of the 

 water descended. Some water flowed down the field-slope, 

 moved under the fences, and found its course to the road-side 

 pool, bringing as much sediment with it as it had power to 

 bear. The corn-fields have been taxed ; the earth built into 

 the highway has been stolen ; the form and bulk of the hill 

 have been changed. So the farmer's fields contributed the 

 material which lies in the bottom of the mill-pond. To some 

 extent, the fields have been scraped down and impoverished. 

 There lies the farmer's property spread over a surface which 

 forms the floor of the sunfishes' home. 



Over every square mile flows some stream. The smallest 

 stream, as well as the largest, occupies a valley; and down 

 its slopes descend the sediment-laden drainage waters which 

 seek the stream to join in its journey to the lower levels. 

 Follow the streamlet. Along every rod of its course we find 

 discharged during a rain the muddy washings of the land. 

 The streamlet grows. Many a lateral rill brings in its con- 

 tribution from the fields which stretch in another direction. 

 Our streamlet flows on, and sooner or later it discharges its 

 burden in some larger stream, which has already grown to its 

 present volume by the contribution of a score of streamlets 



