CLASSIFICATION OF ORE DEPOSITS. 43 



across it. This took place long before the epoch-making time of 

 Werner, and even before the conception of the relative ages of 

 strata had been at all generally grasped. Thus among the Ger- 

 mans we find the terms " Lager " and " Flotze " 1 on the one side, 

 being set off in contrast to " Gang " (vein) on the other. Werner, 

 writing in 1791, quotes Von Oppel's distinctions between Flotze 

 (strata, beds) and Gange (veins), which were published in 1749 ; 

 but without doubt, as mining terms, they go much further back. 

 Beyond this simple indication of the views of the older writers, no 

 attempt will be made here to quote authorities earlier than 1850. 

 This is justifiable because the important works, like De la Beche's 

 Geology of Cornwall and Devon, and Kenwood's Metalliferous 

 Deposits of Cornwall and Devon, are rather discussions- of veins 

 than systematic attempts at classification. 



In the following pages the principal schemes of classification 

 are grouped according to certain relationships and similarities 

 that run through them. It would be interesting to arrange them 

 in chronological order, but points of likeness and unlikeness would 

 not be thus brought out, nor can the influence of one writer on 

 another be so clearly manifested. The underlying object, aside 

 from showing in a bird's-eye view what has been done, is to lead 

 up to an^attempt at a purely genetic classification from which 



1 Lager and Flotze are difficult to render into English while retaining 

 their native shades of meaning. The later writers in Germany (Serlo, 

 Gatzschmann, Von Groddeck, Kohler) define them as being interbedded 

 bodies, each later than the foot wall in formation, and older than the 

 hanging ; and that Lager are much more limited in horizontal extent than 

 Flotze. E. Wabner shows, however, in the Berg. u. Huet. Zeitung, Jan. 

 2, 1891, p. 1, that writers in the earlier part of the century did not entirely 

 restrict the term Lager as regards age relative to the foot and hanging, 

 but applied it to ore bodies, which follow the general bedding, although 

 they may have been introduced much later than the formation of the 

 walls. Thus the frequent occurrence of lead ores in limestone along cer- 

 tain beds (southeast Missouri, for example) would be called Lager. We 

 would apply the terms impregnation, or dissemination, or bed-vein, to 

 such. Flotz we would call stratum, and Lager, as defined by the later 

 authors, " bed " or "seam." Werner, for instance, in his classification 

 of the rock formatibns of the globe, made : I. Urgebirge (Primitive, Pri- 

 mary, etc., having no fossils). II. Secondary, subdivided into A. Ueber- 

 ganggebirge (Transition, more or less metamorphosed sediments, but fos- 

 siliferous). B. Flotzgebirge (Unaltered strata). From this the meaning 

 of Flotz can be grasped. By contrast, a magnetite lense is a good illus- 

 tration of Lager. 



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