ON GEOLOGICAL NOMENCLATUEE. 353 



It SO happens that the Carboniferous rocks are the oldest known 

 in Switzerland ; there is, therefore, no colour settled by the Federal 

 Commission for Silurian and Cambrian, &c., rocks. Professor 

 Kenevier has, therefore, had to chose one, and he has represented 

 them by a pale crimson, which is used on their map for the 

 crystalline schists and gneiss, his idea being that these may partly 

 represent the missing older Palaeoz oic rocks. 



. So much for the conventional colours for geological maps, and for 

 the significance of the coloured bands of which the diagram is com- 

 posed. We must pay attention now to what the Professor calls the 

 Hierarchy of the sub -divisions, for of this he makes rather a 

 cardinal point. By this term is meant the different values given to 

 words which denote divisions and sub-divisions, and so on. It is 

 remarked, in zoology and botany there is a hierarchy of terms 

 which are not allowed to be transposed; e,g., Kingdom is a larger 

 group^than class, this than order, below which come family, genus, 

 species: all these must be used in the proper order: — thus, an 

 Order cannot be divided into classes, — the less into the greater; the 

 word sub-order must be used if a sub-division is required. The 

 rank of these words is universal and fixed in the sciences mentioned, 

 but, as pointed out, is not so in geology. The words system, stage, 

 group, or era, period, epoch, have quite different ranks attached to 

 them by different authors ; some divide a system into stages, others 

 stages or formations into systems, and so on. It is held that this is 

 very anomalous and should be rectified. Professor Eenevier 

 suggests that a set of words should be agreed upon which should 

 everywhere, in geological use, have the same value. To begin 

 with, he regrets as hierarchical terms the word formation (and 

 in French the word terrain, also to which we have no exact 

 equivalent in English) the former word being reserved to signify 

 mode of formation; e.g., marine, estuarine, &c. This is certainly 

 to use the word in a more accurate way, and no doubt it would b e 

 well to follow his suggestion. "We are, however, rather short 

 of words to be applied to a mass of strata, and should be almost 

 confined to the word system. 



