ANNIVERSAEY ADDRESS OP THE PRESIDENT. CI 



could only get a sufficient nu^iber of sections from all parts of the 

 world, all these local gaps would be filled up, and we should have 

 one unbroken sequence of formations, occurring in some part or 

 other of the earth's surface, from the lowest Silurian or even Lau- 

 rentian beds to the most recent Tertiary or Quaternary deposits. It 

 would be an interesting task for any geologist to undertake to 

 supply this want, and to point out the gradual succession of beds 

 where they can be found, showing how they pass almost insensibly 

 from one into the other, as the Ehaetic beds are now shown to form 

 an intermediate zone or passage from the Keuper to the Lias. "We 

 should then see by what almost insensible gradations the crust of the 

 earth has been successively formed, and what were the conditions of 

 life, or some of them at least, which led to the gradual introduction 

 of new forms of life in some places, and their partial extinction in 

 others. And as we have now learnt to recognize the fact that the 

 extinct Mammalia of the Postglacial period had not all ceased 

 to exist before the first appearance of man, we should also probably 

 learn that at no period of the earth's history were all the forms of 

 life destroyed before the introduction of new ones ; but that a partial 

 renewal only took place, and that somewhere or other the witnesses 

 of one period lived on with the new creations to keep up an un- 

 broken chain in the history of organic life from its earliest dawn to 

 the present day. 



Another point to which I would invite attention is one of greater 

 difficulty ; it requires the serious aid of chemistry, mineralogy, and 

 the laws of physical forces. The study of the older crystalline and 

 metamorphic rocks has of late years greatly occupied the attention 

 of many of those geologists who have examined the chemical and 

 mineralogical conditions of formations. "We are told that heat alone 

 could not have produced the results we see; that water was an 

 essential element in all these metamorphic operations ; and we find, 

 in the works of Sterry Hunt, Daubree, Evan Hopkins, Delesse, Desor, 

 and others, that even a high degree of temperature was not always 

 necessary to produce these changes. Many of those results which 

 have hitherto been considered as the efi*ect of igneous action, are 

 now believed to be owing to chemical action continued through long 

 periods of time. It therefore appears that the time is come when 

 it is desirable to investigate this question ; whether the theory of 

 central incandescent heat is tenable ? Whether the plastic condition 

 of the earth, to which its oblate spheroidal form has been attributed, 

 be not owing to an aqueous rather than to an igneous origin? 

 Water is an essential element in every rock, not only mechanically 

 but chemically; and without attempting to revive the doctrine of the 

 Wemerian school, it may be questioned whether we have not some- 

 times been disposed to overlook the importance of the part it has 

 played in the construction and solidification of our earth. 



Another important subject arising out of this question, or rather 

 accompanying it as a corollary, would be, whether the solidification 

 of the earth began at the circumference, after its formation, as is 

 assumed by the advocates of the central-heat theory, or whether the 



