20 



NATURE 



{Nov. 3, 1887 



The same restriction vacated another office that had been 

 filled by formation, and to this office no appointment was 

 made. I refer to the use of the word to denote indefinitely an 

 aggregate of strata — as in saying, this formation should he 

 called a series rather than a system. This is an important 

 function, for which some provision must be made. I suggest 

 that we may advantageously enrich our language by the 

 permanent adoption of terrane, a word whose English meaning 

 has not been well established. 



The fixation of the chronologic terms creates a similar diffi- 

 culty. We have crystallized out of our magma the terms era, 

 period, epoch, and age, and there remain in the ground-mass 

 only eon, cycle, and time. Of these, ^^«has a poetic connotation 

 which seems to unfit it for this particular use ; cycle implies 

 repetition or recurrence ; and time has been so generally applied 

 to unlimited duration that it is difficult to apply it also to limited 

 duration, even though the nature of the limitation be indefinite. 

 On the whole, time seems open to the least objection, but I can- 

 not help regretting that either period ox age, both of which have 

 heretofore passed current in the indefinite sense, was not reserved 

 by the Congress for that function. With English-speaking 

 peoples the word eon could have been better spared for the 

 definite series. 



But while the terms selected by the Congress are not beyond 

 criticism, the benefits to be derived from an agreement in an 

 orderly system are so great that I for one shall unhesitatingly 

 adopt them as they stand — provided, of course, that the Con- 

 gress makes no effort to improve its selection. A small reform 

 of this nature yields its profit to this as well as future genera- 

 tions, and I hold it a duty to favour even those reforms which 

 involve so much effort and pains that their blessings cannot be 

 realized by those who initiate them. Such are the exchange of 

 our English spelling for a rational system, and the exchange of 

 decimal notation in arithm:tic for a binary notation. My appli- 

 cation of the new nomenclature begins with this address, in the 

 preparation of which I have experienced its utility. That you 

 may have no difficulty in interpreting my reformed language, I 

 have placed the taxonomic legend on the wall, with the addition 

 of the complementary indefinite terms — terrane and time. 



Terranes. 



Group. 



System. 



Series. 



Stage. 



Times. 

 Era. 

 Period. 

 Epoch. 

 Age. 



There are propositions before the Congress to distinguish the 

 names of individual groups, systems, series, and stages by means 

 of terminations, those of the same rank having the same termina- 

 tion. Thus it is proposed by a Committee that every name of a 

 group shall end in ary — Tertiary, Primary, Archeary ; it is pro- 

 posed that names of systems end in ic — Cretacic, Carbonic, 

 Siluric ; it is proposed that names of series end in ian — Eifelian, 

 Laramian, Trentonian ; and it is proposed that stage names 

 terminate with in. Another Committee suggests that ic be used 

 for stages instead of systems. The adoption of such a plan 

 would enable a writer or speaker to indicate the taxonomic rank 

 of a terrane without adding a word for that purpose. If he 

 regarded a certain tc-rane taking its name from Cambria as a 

 system, he would call it the Cambric ; if he esteemed it only a 

 series, he would say Cambrian ; and there would be no need of 

 adding the word system or series in order to express his full 

 meaning. Conversely, the reader or hearer would always learn 

 its taxonomic rank, or supposed rank, whenever a terrane was 

 mentioned. These I conceive to be the advantages derivable 

 from the change, but they would not be the only effects. It 

 would become impossible for a geologist to name or allude to a 

 terrane without declaring its rank, and the consequences of this 

 would be evil in many ways. In the first place, one could not 

 discuss terranes from any point of view without expressing an 

 opinion as to their taxonomy, and the change would thus contra- 

 vene one of the most important rights of opinion — namely, the 

 right to reserve opinion. Again, geologists who differed as to 

 the rank of a terrane would necessarily terminate its title differ- 

 ently, and a needless synonymy would thus be introduced. In 

 the third place, the created necessity for taxonomic discrimina- 

 tion on all occasions would tend to direct undue attention to 

 taxonomic problems. Taxonomy would be conceived by many 

 geologists as an end instead of a means, just as correlation has 

 been conceived, and energy would be wasted in taxonomic 



refinement and taxononomic controversy. It is convenient for 

 purposes of description and comparison to classify the strata 

 that constitute a local columnar section in phalanges of various 

 magnitude or rank, but the criteria on which we depend for 

 discrimination are in the nature of things variable, and offer 

 ground for endless difference of opinion ; and it would be 

 extremely unfortunate to have such differences perpetually 

 brought to the foreground. 



Another subject considered by the Congress is the nomencla- 

 ture of palaeontology. A Committee appointed for the purpose 

 formulated rules for the establishment of the names of genera and 

 species, and their report was adopted by the Congress. I have 

 no opinion to express as to the wisdom of the rules, but it is a 

 matter of surprise that a body of geologists assumed to speak 

 with authority on the subject. From one point of view palaeonto- 

 logy 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 inti- 

 mate relations of systematic mineralogy are with chemistry. 



Yet another projected work of the Congress is the classification 

 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 advant- 

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

 features of a classification were well established and the residuary 

 discrepancies were recognized as unessential, it is conceivable 

 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 funda- 

 mental 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 vigour, and with the aid 

 of new and important methods. With the rapid growth of know- 

 ledge and ideas, classifications are continually 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 classification 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 undertakings 

 of the Congress, the classification of terranes and the unification 

 of map colours. The Congress is attacking these subjects in- 

 directly 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 classification 

 to be applied to the entire earth, and the selection of a colour 

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

 map=. But at the Berlin session the Committee in charge of 

 work on the map of Europe pressed the Congress for the deter- 

 mination of questions on which hung the completion of the map, 

 and many hasty decisions were reached, while not a few disputed 

 points were referred to the Map Committee. The debates indicate 

 that much or all of this work was provisional or of merely local 

 application, but the resolutions adopted show little qualification. 

 It should be added that the official minutes of the meeting are. 

 still unpublished. In view of the uncertainty thus occasioned I 

 shall not attempt to characterize the attitude of the Congress 

 on the subject of classification, but shall merely develop my 

 individual view. 



It is the opinion of many who have discussed the general 

 classification of terranes by convention of geologists that the 

 smallest unit of such classification should be the stratigraphic 

 system. What is a stratigraphic system ? The Congress implies 

 a definition in saying that a system includes more than a series 

 and less than a group, and that the Jurassic is a system ; but this 

 gives only a meagre conception, and we need a full one. As the 

 problem of classification demands a true conception of a systern, 

 and as there is reason to believe that a false conception is 



