172 GROVE KARL GILBERT— DAVIS [MemoirS [vouxxi, 



so cumbrous that no one could learn it; if the scheme were specially adapted to the needs of 

 each separate sheet it might be simple enough in each instance, but the color alphabet would 

 then vary from sheet to sheet in a manner that would be confusing. Hence after mature de- 

 liberation a scheme was adopted in which both of these difficulties are reasonably avoided; a 

 scheme which calls for the assignment of certain well-defined notational devices or "patterns" 

 to certain classes of formations, but not to specific formations. The formations were to be 

 grouped in four classes; crystalline schists, igneous rocks, fossiliferous elastics, and superficial 

 deposits. Each class would use the entire gamut of color, but the colors would be printed in 

 different patterns for the different classes. Thus the scheme was made "uniform with refer- 

 ence to the broad features of classification, and plastic with reference to details." 



The "study and experiment," of which the standard map scheme now familiar in the 

 geologic folios was the outcome, appear to have been devoted not alone to the choice of colors 

 and patterns with regard to the legibility of their combinations, but also to the practical details 

 of reproducing the patterned colors satisfactorily by lithography instead of by hand, and this 

 was something of an innovation; for it will be remembered that although a number of colored 

 maps had been produced by mechanical presswork for certain departmental and State surveys 

 in an earlier decade, their color spaces were seldom of fine texture; and also that the geological 

 maps of European surveys were in the eighties usually colored by hand. Hence the proposal 

 to run off from a press a large number of sheets in a large series of maps with many small and intri- 

 cate color spaces was something of a novelty; and as the proposal also included minute color 

 patterns which had to vary with the intricate color spaces, it was a complicated novelty. Study 

 and experiment were evidently necessary before it could be safely undertaken. 



When the final plans were formally announced, Powell properly assumed full responsibility 

 for them, but at the same time expressed his indebtedness to his fellow workers for the aid 

 they had given: 



This subject has been one of constant study by the Director for many years. He is indebted to his col- 

 leagues on the Survey for much careful experimentation and many valuable suggestions. He is especially 

 indebted to Messrs. Gilbert and McGee to whom the subject in all its parts and in all stages of investigation 

 has been referred from time to time. Mr. Gilbert has supervised the experiments and selected the specific 

 patterns in the several classes. 



The precise extent to which Gilbert, as chief adviser, collaborated with Powell in the 

 development of the color scheme and other features of the plan is not known; for although it 

 is recalled that the various kinds of lines, triangles, and dots used in the color patterns were all 

 minutely tested and specified by Gilbert before he regarded the scheme as satisfactory, there 

 is unfortunately no sufficient record of the contributions which he and his senior made to the 

 total result. The director of the survey undoubtedly had much to do with the scheme in a 

 general way, consistent with his capacity as an original thinker and his duty as an administrator; 

 while his chief geologist also had much to do with it, as would be expected from his painstaking 

 ability to follow a problem to its very end. There must have been from time to time occasions 

 when wise choice had to be made among several competing devices, and there must have been 

 continued need of keeping a trained and patient hand on every detail of the various devices 

 with respect to their practical availabihty. We may therefore beheve that the choice was the 

 choice of Powell, but that the hand was the hand of Gilbert; and it may even be surmised that 

 the patient hand sometimes guided the occasional choice. 



No formal changes were made in the plan of the geologic folios for over a decade; the 

 changes that were gradually introduced were those of natural and healthy growth. The most 

 important was the development of the folio texts far beyond the original intent both in quantity 

 and quality. The text has often come in later years to occupy several full sheets of letter 

 press in a folio and to involve technicalities of nomenclature and complications of discussion 

 that can be understood by none but a trained geologist, and a well-trained geologist at that. 

 But it will appear in a later section that when it came to be Gilbert's duty to prepare a folio 

 he held more closely than many of his colleagues to the idea that the text should be easily 

 intelligible, although in so doing he omitted matters that might, in the opinion of some folio 

 users, have been profitably included. 



