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in assaying, when his slag being too basic has eaten its way into the clay 

 crucible appearing when the crucible is broken through its substance 

 here and there in spots and streaks ; Lehmann, who has made a most 

 exhaustive study of the whole region points to the fact that this zone 

 is not always present, and states it to be his belief that the granitic 

 material forming the flammen in the schist has not been derived from 

 the granulite magma, but is due to the deposition of the granitic 

 material in spaces formed by the separation of the foliae of the schist, 

 under the great stresses to which the region has been subjected, the 

 granitic material in question having been derived from later intrusions 

 which elsewhere can be clearly seen to cut the granulite. From per- 

 sonal observation, however, I must say that appearances are strongly 

 in favor of Naumann's view, that along the narrow zone of the imme- 

 diate contact the granulite magma has eaten into the schist to a certain 

 distance, a phenomenon which is quite intelligible and perhaps in cer- 

 tain cases to be expected, but which is quite distinct from the whole- 

 sale transformation of the schist into granite by the mysterious process 

 of " granitization." 



In how far this process of transfusion which is considered by 

 Michel- Levy and other French geologists to play so important a part in 

 the origin of the crystalline schists is really active, must be determined 

 by detailed studies of the deeper seated granite contacts and of the 

 so-called Archean areas in various parts of the world. 



Such studies in the case of Archean areas are "presented in the 

 recent maps, with accompanying explanatory texts, issued by the geo- 

 logical survey of Baden, and whose titles are given above. This survey, 

 following the lead of those of Prussia, Saxony, and Hessen, was con- 

 stituted in 1888 for the purpose of mapping in detail the Grand Duchy 

 of Baden, an area of 5843 square miles, on a scale of -^-^\-^-^- For this 

 purpose the territory in question has been divided into 170 sections. 

 Work was begun in 1889 and maps of twelve sections have already 

 been published. As about one-quarter of the Grand Duchy of Baden 

 is underlain by Grundgebirge including the well-known area of the 

 Black Forest, ample opportunity is given for a thorough study of these 

 ancient rocks. Six of the maps already published are in areas of the 

 Grundgebirge ; of these three have been mapped by Dr. Sauer, to whom 

 we are already indebted for his valuable contributions to our knowl- 

 edge of the ancient crystalline rocks of Saxony. The maps are among 

 the best which have yet appeared of any Archean region, and serve to 



