Oti the Maintemmce of the Uarth's Internal Heat. 157 



XII. On the Maintenance of the Earth's Internal Heat. By 

 J. G. GooDCHiLD, Esq., F.G.S., F.Z.S. 



(Read 20th April 1898; received for publication April 1899.) 



[Abstract.] 



The Earth is supposed by many physicists to be parting 

 with its original heat at a rate which would seem to point to 

 its consolidation having taken place within a few millions of 

 years from the present time. On the other hand, the facts 

 made known by geologists seem to require a very much longer 

 period than the time referred to. It was pointed out that 

 there are several causes in operation which tend to retard 

 the assumed rate of cooling ; while, on the other hand, there 

 appear to be other causes which are giving rise to an evolu- 

 tion of heat within the Earth's crust, and which thereby help 

 to maintain a high temperature at a variable distance below 

 the surface. The general conclusion arrived at was that the 

 Earth's internal heat is not entirely, or perhaps is not at all, 

 a remnant of its original heat, or that which it had on con- 

 solidation ; but that the heat in question is due largely to 

 dynamic causes, partly aided also by surface-oxygenation, 

 and by chemical reactions of various kinds both at and 

 below the surface. The dynamic causes were regarded as 

 referable to the effects of contractional crushing, and to the 

 conversion of motion into heat in those cases where earth- 

 creep is taking place. Some cases of earth-creep may arise 

 through the unequal loading of the Earth's crust by the 

 joint action of denudation and deposition ; others may result 

 from the subterranean transfer of rock-materials from one 

 locality to another by plutonic action. These rocks may have 

 been first softened by the transfusion of alkaline solutions, 

 carried downward by osmosis from the floor of the ocean, 

 and the material may then have been very slowly squeezed 

 out along the ocean margins. Disturbances of equilibrium by 

 such causes, and the consequent lateral flow of rock-material, 

 must generate a certain amount of heat. Even luni-solar 

 gravitational energy cannot rightly be left entirely out of 

 account in such considerations as these, because it is quite 



