COLOR SCHEME. 25 



The European international geologic color scheme embodies the results of pro- 

 longed consideration by the international committee who were charged by the 

 Geological Congress with the duty of preparing the map of Europe. In it can be 

 recognized some elements of the French usage, particularly in the colors employed 

 for the Mesozoic and Tertiary terranes. German influence appears in the selection of 

 tones for Paleozoic terranes, and the familiar association of gray with Carboniferous 

 and of pink with the ancient crystalline schists is an obvious result of general prac- 

 tice. So also is the use of strong, brilliant colors for the igneous rocks. The writer 

 is not definitely informed regarding the discussion of principles through which 

 the result was reached, but by a study of the color schemes in the light of what is 

 published concerning the controlling principles, it would seem that the committee 

 recognized (1) established usage, (2) the order of prismatic colors from purple 

 through blue and green to yellow for that portion of the scheme relating to the 

 Triassic and post-Triassic terranes, and (3) the arbitrary principle that Mesozoic 

 terranes should be distinguished from Paleozoic by a very decided contrast of light 

 and shade, the Paleozoic terranes being indicated by dark colors. 



The European color scheme is exceedingly well adapted to delineate the geology 

 of Europe and would apply well to that portion of western North America in which 

 the Mesozoic and Tertiary formations occupy large areas in contrast to the Paleozoic 

 terranes, as they do in Europe also. The map of Europe is very clear and legible, 

 the base map having been kept free from confusing details and the colors having 

 been selected and printed with great skill. The color scheme thus commends 

 itself through the beautiful appearance of the map. It must not be forgotten, 

 however, that Europe presents a special form of geologic structure. The continent 

 is made up of extensive areas of Mesozoic and Tertiary strata surrounding rela- 

 tively small exposures of Paleozoic terranes. This arrangement of younger strata 

 about older nuclei is, from the point of view of the cartographer, the most important 

 feature which the continent presents. The committee with good reason sought to 

 emphasize the fact, and through that emphasis the map of Europe gains in expression 

 and educational value. The greater part of the map is easily legible, being covered 

 only by the light colors which are used for the Mesozoic and Tertiary, and the 

 difficulties which arise in attempting to read the geology of the minor Paleozoic 

 areas are not forced upon the attention. 



But the international color scheme is unfitted to lands in which the Paleozoic 

 terranes predominate and are minutely subdivided, for the density of the colors 

 selected for the Paleozoic would produce a map that would offend good taste and 

 be illegible. Moreover, inasmuch as the range of prismatic colors from purple, blue, 

 and green to yellow is preempted in the European color scheme for Mesozoic and 

 Tertiary terranes and the reds are assigned to the ancient crystalline and eruptive 

 rocks, the choice of colors remaining available for the Paleozoic is much too limited 

 for satisfactory discriminations. This is at once evident on an examination of the 

 Paleozoic areas as represented on the international map — such, for instance, as the 

 coal fields of Belgium and France, or the peninsula of Brittany, or Wales and Scot- 

 land. Although the distinctions are limited to a few great systems they are recog- 

 nizable only on close inspection and the areas are indistinguishable from one another 



