RECENT ADVANCES IN SCIENCE 25 



Derbyshire, etc.," ibid., 9, p. 87 ; M. Macgregor, et alii, "The 

 Iron Ores of Scotland," 1920, 11, p. 236). For the Cumberland 

 ores Mr. Bernard Smith arrives at the conclusion that the iron 

 has been derived by solution from the overlying New Red 

 Sandstones, and has been deposited by metasomatic replace- 

 ment in the underlying Carboniferous Limestone, the solutions 

 travelling along faults and other fissures. A similar view is 

 held by Prof. Sibly in regard to the iron ores in the Car- 

 boniferous Limestone of the Forest of Dean. 



The iron ores of Scotland are classified as follows : i. Bog 

 ores of recent origin ; 2. Haematite ores of different ages ; 3. 

 Carboniferous clayband ores ; 4. Carboniferous blackband ores ; 

 5. Jurassic ores. Of these the most important economically 

 are the claybands and blackbands ; but the ironstones of 

 the Millstone Grit volcanic rocks in Ayrshire, although not 

 likely to be of economic value, are perhaps of the greatest 

 scientific interest, as they are probably of lateritic origin. 

 This view is supported by their association with the bauxitic 

 claj^s above-mentioned. 



Recent developments in the great iron-ore deposits of 

 Kiruna (Swedish Lappland) have led to a modification of Dr. 

 Per Geijer's well-known views as to their origin {Sver. Geol. 

 Undersok, 191 8, Arsbok 12, No. 5, p. 22). He has found con- 

 tact metamorphic phenomena in the hanging wall of the ore 

 bed that correspond exactly to those hitherto exclusively found 

 o-n the footwall side. The ore body is now consequently be- 

 lieved to be intrusive rather than extrusive. Dr. Geijer thus 

 returns to Stutzer's original view, but regards the ore body as 

 a sill rather than a dyke. The enclosing porphyry bodies are 

 still believed to be of extrusive origin. 



A useful summary of ore genesis in the Archaean of India 

 is presented by Dr. L. L. Fermor in his presidential address to 

 the Geological Section of the sixth Indian Science Congress 

 {Proc. Asiatic Soc. Bengal, 1919, 15, pp. 170-95). He deals 

 with the syngenetic sedimentary deposits exemplified by iron 

 and manganese ores ; syngenetic igneous deposits typified by 

 chromite ores in serpentine ; and epigenetic deposits, such as 

 lodes of copper, lead, zinc, and gold, due to granitic intrusion 

 into the Dharwar (Archaean) sediments. 



According to W. R. Jones {Bull. Inst. Min. and Metal, March 

 1920, 186, pp. 1-27) the tin and tungsten deposits of the 

 world are to be classified as follows : i . Segregation deposits ; 

 2. Contact metamorphic deposits ; 3. Pegmatoid deposits (in 

 pegmatites, aplites, quartz-porphyries, andrhyolites) ; 4. Quartz 

 vein deposits ; 5. Replacement deposits. From his study 

 it appears that cassiterite is a higher temperature mineral than 

 wolframite ; and deposits in which wolframite and cassiterite 



