IIo REGINALD A. DALY 
He favors the view that this condition applies to many alkaline 
rocks. 
Among the consequences of undersaturation, according to 
Shand (p. 510), is the tendency of foyaitic or phonolitic magmas 
to enter ‘‘into chemical combination with the silica of invaded rock 
masses. The reactions thereby induced would be exothermic, and 
would tend to raise the temperature of the magma..... The 
access of heat produced in this way would in turn enable the magma 
to perform a further amount of work in the way of mechanical 
solution.”” One is reminded of Ramsay’s conclusion that the 
umptekite of the Kola Peninsula is probably due to syntexis 
between nephelite-syenite magma and siliceous sediments.* An 
analogy is found in Ussing’s explanation of important masses of 
quartz syenite and soda granite in the Julianehaab district as 
products of reaction between augite-syenite magma and sandstone. 
Quensel, too, assumes syntexis between the umptekitic magma of 
Almunge and older granite, giving the observed transition between 
the corresponding formations.’ 
Shand notes the relative insignificance of alkaline foes in 
volume; the dominance of oversaturated rocks among major intru- 
sions; the dominance of saturated and undersaturated rocks 
(including basalts) among lavas and minor intrusions; and (p. 512) 
the 
strong suggestion that undersaturation may be characteristic of the deeper 
zones of the lithosphere, as oversaturation is of the higher. .... Those 
igneous rocks which have been brought up most rapidly from the earth’s 
interior, and have solidified most rapidly in or on the crust, are to a marked 
extent undersaturated. Those which have slowly worked their way up into 
the crust (and have hence had abundant opportunity for absorbing silica) are 
found to be predominantly oversaturated. 
Comparison may be made with the idea of granitic, continental 
maculae overlying a basaltic earth-shell. 
«W. Ramsay, Fennia, XI, No. 2 (1894), pp. 74, 95. As above noted, Winkler 
has given proofs of the solution of quartz in basic Alpine lavas which he considers as 
belonging in the alkaline suite. 
2N. V. Ussing, Meddelelser om Grinland, XXXVIII (1911), 59, 191, 197, 363; 
366; P. D. Quensel, op. cit., XII (1914), 196. 
