EDITORIALS. 297 



Mr. M. R. Campbell ; the Lassen Peak sheet and Sacramento 

 sheet in California, the geology of the former by Mr. J. S. Diller, 

 that of the latter by Mr. W. Lindgren, The character of the 

 geology is equally diverse, embracing highly metamorphosed 

 sediments in the first case, slightly modified strata in the second, 

 and in the last two, metamorphosed igneous and sedimentary 

 rocks associated with volcanic lavas. We notice with satisfaction 

 the prominence given to economic features as well as the clear 

 statement of facts regarding the dates at which the work was 

 prosecuted, and the investigators who are to be credited with the 

 work, two essential elements in forming a judgment as to the 

 character of the results. 



While the atlas sheets are alike in size they differ in scale 

 from 1-250,000 to 1-62,500. The relative areas, however, are 

 shown upon an index map on the cover of the atlas. These 

 differences of scale are desirable because of the variable import- 

 ance of the different parts of the country, and the variability in 

 the character of the geology, which may be best represented 

 upon maps of different scales. Such flexibility is a distinct 

 advantage. The success of the effort to introduce greater 

 elasticity into the method of coloring geological formations will 

 be variously estimated. It is not possible to form a fair opinion 

 of the merits of the system from the few examples of it fur- 

 nished by the four atlas sheets already finished. But it would 

 seem that the prominence accorded to pattern in the system, by 

 making it a basis for the distinction of the main subdivisions of 

 rocks : sedimentary, igneous and metamorphic, has been nullified 

 by the lithographer, who has succeeded so admirably in reducing 

 the lining to a mechanical minimum that the detection and 

 recognition of patterns is a test of eyesight. We appreciate the 

 difficulties attending the application of any comprehensive 

 scheme of colors to so large and diversified a series of atlas 

 sheets as that which will constitute the map of the United States, 

 and look upon the efforts so far made as having advanced the 

 problem without completely solving it. In the meantime the 

 results already obtained by the geologists of the Survey in many 



