1 64 ALFRED C LANE 



out like fluid from a filter press. When this happens we have the 

 aplitic red rock associated with the Duluth Gabbro described most 

 fully and lately by F. F. Grout^ or with that of Mount Bohemia, 

 so fully described by F. E. Wright.^ If one supposes this segrega- 

 tion conducted on a still larger scale or so that the crystalhzation 

 shall be somewhat coarser and the grain coarser, the logical outcome 

 would be a granite. This is just what Dresser finds that the 

 advance of mining operations has conclusively proved^ by showing 

 that masses of granite have no separate connection with the earth's 

 interior. 



The largest mass of differentiated hornblende granite mentioned 

 by Dresser is three-quarters of a mile long by one-quarter of a mile 

 wide, with a coarser pegmatite border two or three feet wide and a 

 porphyritic texture throughout. This granite *'is an indication 

 rather than a cause" of the presence of acid waters in the mag- 

 matic residue needed to produce serpentine and asbestos. It is 

 interesting to note that Bowen starting with peridotite as a mono- 

 minerahc differentiate suggested that the region "may" furnish a 

 "complementary granitic differentiate." He is apparently right! 



Now the laws of physics and chemistry are universal. If this 

 has happened in the Lake Superior region and the Eastern Townships 

 it must have happened in many other places. One is tempted to 

 consider the Mull pitchs tones'* the "leidleites and inninmorites " 

 which (a) apparently occur only as intrusions, (b) are high in 

 primary water, (c) are glassy at the center and stony at the sides, 

 i.e., coarser at the margins, as representing such a magma as that of 

 the red rock of Wright, of Grout, etc., chilled more quickly and 

 without loss of water, but yet like many aplites or the granite de- 

 scribed by Dresser, consoHdating more slowly at the margin. This 

 I have shown is more likely to happen when the initial magma tem- 



' "A Type of Igneous Differentiation," Jour. GeoL, Vol. XXVI (1918), p. 618. 



^ Report Michigan Geological Survey (1908), p. 387. 



3 "Granitic Segregations in the Serpentine Series of Quebec," Transactions of the 

 Royal Society of Canada (1920), pp. 7-13. Compare also N. L. Bowen, "Differentia- 

 tion by Deformation," Proc. Nat. Acad. Sci. (1920), p. 160. 



■»£. M. Anderson, and E. G. Bailey, Qtmrt. Jour. Geol. 5oc., Vol. LXXI (19 16), 

 pp. 205-16, London. 



