President's Address. 



9 



faith ; for my own part, I have never hesitated to question 

 a dogma from a divine if I thought he was wrong in his 

 theology, and have now none in trying to refute these state- 

 ments, believing, as I do, that geology is a science of facts, 

 not of faith. Let us consider his first statement, " That 

 all the consolidated strata, viewed chemically, bear marks 

 of the subjection to an action of heat agreeable to the 

 theory of the earth's refrigeration in direct proportion to the 

 age of their deposit." Where the Rev. Mr Harcourt finds 

 proof for this statement I have failed to see in his report. 

 If he believes, as most geologists do, that the granite is 

 the lowest rock we know in the crust of the earth, why 

 can he not show the marks which bear evidence of greater 

 chemical action at the base than is borne at the summit of 

 the formation ? As I have said before, not being able to see 

 any difference, mineralogically or chemically, in the struc- 

 ture of granite, I am therefore bound to reject this portion 

 of the statement. And now with regard to the second half 

 of his first proposition, which states " That they [the rocks] 

 show that action [meaning heat, or chemical action due to 

 heat] most explicitly in the presence throughout, but more 

 abundantly as the series descends, of that peculiar form of 

 silica which is chemically reproduced by the action of 

 heated volatile matter." Now, in dealing with this latter 

 statement, I feel at a loss to see for one moment how the 

 granites, the gneiss, and schist, and greywackes, bear evi- 

 dence of being exposed to greater heat than we find ex- 

 hibited in the Carboniferous epoch. 



I have already shown in my paper on the Aqueous Origin 

 of Granite, that there, and also in traps, cavities exist, con- 

 taining fluids which entirely fill the spaces at a temperature 

 not higher than 94° of Fahrenheit, demonstrating that 

 those cavities could not have been filled at a higher tem- 

 perature. With this fact, along with others I have men- 

 tioned, I cannot accept the latter portion of Harcourt's 

 dogma. And I now beg you to remark, that the first dogma 

 relates to the consolidated strata, the second only to igneous 

 minerals ; let me repeat it : " The igneous minerals were 

 formed by molecular aggregation at a heat not exceeding, 



vol. nr. B 



