PROCEEDINGS FOR 189() XCVII 



geological ages, though still in this year, 189b', regarded as in all cases a 

 fused or molten mass, erupted or irrupted, all of which terms are still 

 prevalent in connection with its description. And yet all the facts I 

 have referred to, and numberless others that are recorded, are absolutely 

 opposed to the idea of upheaval and intrusion, which imply great mechan- 

 ical force, high temperature, and the pushing aside, or the bodily lifting 

 up, and removal of the matter which occupied the space now occupied b}' 

 the granite. 



Supporters of the intrusive theory should explain what, and whence 

 derived, is the material that has filled the void that must have been occa- 

 sioned by the upheaval and irruption of the granite ; or, in the case of 

 the stratified rocks that went down to central heat to get altered, what 

 became of the solid material of the lithosphère they must have displaced 

 in doing so. In no case that has come under my notice is there any 

 reliable evidence of such forces, or transposition of matter, having oper- 

 ated in the transaction. This unorthodox but now admitted fact could 

 only be explained by metamorphism, which is undoubtedly true ; but 

 the dogmas of intrusion, upheaval and central heat remain. 



All writers agree in regarding granite and gneiss as practically ident- 

 ical in mineral composition — igneous and intrusive when massive; when 

 schistose or gneissic, metamorphic after and from pre-existing stratified' 

 deposits, by a roundabout and unnecessary jack-in-the-box process of 

 Avhich and for which the rocks themselves afford no evidence. 



All the facts can be rationally explained without this retrogressive 

 recurrence to central heat. Contraction, as suggested by Ramsay, and 

 referred to previously together with ejection and denudation, have 

 done more than upheaval and intrusion in moulding the form and out- 

 line of the lithosphère. They are themselves adequate to account for all 

 the phenomena it presents, including the recurrent local formation of 

 granite, as well as the analogous recui'rent ejection of volcanic matter, 

 which does not essentially differ from granite, though produced by dif- 

 ferent processes and under different surroundings and conditions. 



Inasmuch as it is impossible to produce artificially either the condi- 

 tions, or the surroundings, which prevailed either in the early or in the 

 later stages of the formation of granite and granitoid crystalline rocks, 

 especially that most important one, time, and its accompanying slow and 

 continuous dynamic and thermo-chemical action, so, many of the con- 

 clusions, based on experiments and investigations in which these important 

 factors are necessarily^ absent, must themselves be regarded as more or 

 less interesting speculations as to what may have been in the past. But 

 when the conclusions are jDlainly negatived by careful investigation of 

 the rocks, we are certainly justified in rejecting them. Such a one, the 

 writer holds, is the upheaval and intrusion of hundreds of square miles of 

 granite. 



Proc, 189R. G. 



