THE USE OF LOCAL NAMES LN GEOLOGY 169 



be devised than the existing scheme of vaguely defined geolog- 

 ical formations, having no comparable limits in different prov- 

 inces and even diverse values in different parts of the same 

 province. A natural, yet elastic foundation must be secured. 

 Practical experience and the demands of the times quickly 

 pointed out a suitable plan. So well has it served the purpose 

 and so readily adaptable is it to the varying conditions met 

 with on all sides, and the unforeseen exigencies constantly aris- 

 ing, that it has brought under its standard nearly every practical 

 field geologist. 



The method of designating geological formations by geo- 

 graphical names certainly does greatly increase the nomencla- 

 ture, at times seemingly to a burdensome extent. This appears 

 to be the only objection that has been yet urged against it that 

 might call for notice. Yet, to all, except those who do not care 

 to go beyond the ordinary text-book in geological work, even 

 this seems hardly necessary, since it is offset by so many man- 

 ifest advantages. 



It may be truly said that no greater boon to the working 

 geologist has been yet devised, than the plan of designating, 

 geographically, geological units irrespective of exact position or 

 age. Incorporated in the new plan are all the salient good fea- 

 tures of the old method, while none of the objectional ones are 

 retained. Since its adoption a vast mass of valuable information 

 has been obtained that was previously unthought of, information 

 that is in a shape to be always used, without the necessity of the 

 user personally going all over the ground again ; the other depart- 

 ments of geology have been greatly aided ; and stratigraphical 

 geology itself has made greater real progress in the short decade 

 that has elapsed since the method with its new impetus came 

 into general use than in all time previous. In the same short 

 period more has been learned about the nature of sedimentation, 

 the actual relations existing between rock formations, and the 

 structure of the lithosphere than was possible before. In fact a 

 rational physical basis for geological correlation and classifica- 

 tion has been found. 



