REPORT OF THE DIRECTOR IQIO IIQ 



cambric of New York, or the adjacent areas, though between indi- 

 vidual mines of the two regions certain similarities may be apparent 

 or genetic relationships indicated. 



The origin of the central Sweden ores is a question still under 

 debate by the geologists of that country. The sedimentary view, 

 which seems to have been the first to gain prominence in the 

 Swedish reports, as is instanced also in the literature of our own 

 Precambric magnetites, apparently has lost favor among the recent 

 workers in the field. Of these, Doctor Johansson, whose paper on 

 the Grangesberg mines has already been quoted, and Professor 

 Sjogren, in his recent contributions, have emphasized the inadequacy 

 of the sedimentary theory as applied to most of the deposits. The 

 present tendency, judging from the later researches, is to consider 

 the deposits as magmatic segregations — an explanation more 

 suited perhaps to the high-phosphorus ores which are included 

 within the granulitic gneisses — or as the result of metasomatic 

 processes that may have accompanied the neighboring igneous in- 

 trusions. The latter explanation applies with special force to the 

 skarn ores and those found in limestone ; while the silicious banded 

 hematites are possibly to be excepted as a separate class with sedi- 

 mentary affinities. The subject, however, is too intricate to be given 

 further attention in this summary. 



The writer wishes here to express his obligations for the guidance 

 and many courtesies that he received during the excursions. It is 

 needless, perhaps, to say that the visits both in Lapland and in 

 central Sweden were crowded with interesting features, scientific 

 and technical, which have found no place in the foregoing notes. 

 To the leaders of the excursions. Doctor Lundbohm for Lapland 

 and Professors Sjogren and Petersson and Doctor Johansson for 

 central Sweden, and to Mr Per Larsson, manager of the Striberg 

 mines, an especial acknowledgment is due. 



