G. K. Gilbert — Congress of Geologists. 435 



paleontology is a part of geology ; from another point of view- 

 it is a part of biology. In so far as it names genera and species 

 it is purely biologic, and it would seem proper that the students 

 of fossils unite with the students of living animals and living 

 plants in the adoption of rules of nomenclature. 



A similar remark applies to the nomenclature of mineralogy, 

 in regard to which no action has yet been taken. The most 

 intimate relations of systematic mineralogy are with chemistry. 



Yet another projected work of the congress is the classifica- 

 tion of eruptive rocks. Up to the present time action has been 

 deferred, and it may reasonably be hoped that no scheme of 

 classification will be adopted. If there existed a system of 

 classification which gave general satisfaction and had stood the 

 test of time, there would be little harm — and little or no advan- 

 tage — in giving it the official stamp of approval. If the main 

 features of a classification were well established and the residu- 

 ary discrepancies were recognized as unessential, it is conceiva- 

 ble that some benefit might be derived from the submission of 

 the matter to an assembly of specialists. But the actual case is far 

 different. Not only is there wide difference as to the classifica- 

 tion of volcanic rocks, but there is no agreement as to the fun- 

 damental principles on which their classification should be 

 based, for we still lack an accepted theory of volcanism. At 

 the same time observation is being pushed with great vigor, and 

 with the aid of new and important methods. With the rapid 

 growth of knowledge and ideas classifications are continu- 

 ally remodelled, and the best is in danger of becoming obsolete 

 before it has been printed and circulated. Should the congress 

 enter the lists, one of two things would occur. Either its classi- 

 fication would be treated like that of an individual and ignored 

 as soon as a better one was proposed, or it would be regarded 

 as more authoritative, and new facts would for a time be warped 

 into adjustment with it. In either case the reputation of the 

 congress would eventually suffer, and in one case science would 

 suffer also. 



There remain to consider the two most important undertak- 

 ings of the congress, the classification of terranes and the uni 

 fication of map colors. The congress is attacking these subjects 

 indirectly by means of a third undertaking, the preparation of 

 a geologic map of Europe, and this method of approach has had 

 the effect of making it difficult properly to interpret its action. 

 There can be no doubt that those who originally organized the 

 work contemplated the enactment of a stratigraphic classifica- 

 tion to be applied to the entire earth and the selection of a color 

 scheme for use either in all geologic maps or in all general geo- 

 logic maps. But at the Berlin session the committee in charge 



Am. Jour. Sci.— Third Series, Vol. XXXIV, No. 204.— -Dec, 1887. 

 29 



