28 I, C. EUSSELL CONCENTRATION AS A GEOLOGICAL PRINCIPLE 



it is not to be understood that it stands alone or is the sole guide which 

 a geologist should follow in reaching for materials of industrial impor- 

 tance. Concentration ia one way or another has filled nature's store- 

 houses, but the origin of the receptacles, their size, association, the con- 

 ditions favoring their preservation, etcetera, are important matters to be 

 considered. The very activities which lead to storage necessitate as 

 a part of their functions depletion in many instances of previous accumu- 

 lations. As in so many other geological processes, destructional and con- 

 structional action are involved in the various processes of concentration, 

 and the result is in many instances the algebraic sum of the two. In 

 dwelling on the process which favors accumulation, the concurrent 

 activities favoring dissipation need to be borne in mind and at some other 

 season given a place of prominence. 



In Conclusion 



From the sands at our feet I have selected a pebble and held it to 

 the light. It is perhaps not a flawless crystal, but can with greater 

 truth be termed bort, which may be put to industrial uses instead of 

 treasured on account of its beauty or rarity. The pebble, as I have 

 identified it, is a true and broadly underlying principle, which is worthy 

 of recognition, which should be given a place by geologists, and espe- 

 cially in books dealing with the application of our science to commercial 

 industries. By understanding the methods by which storehouses of the 

 earth have been filled, the seeker for hidden treasures will be better 

 able to locate his claims. 



