304 ANNUAL OF SCIENTIFIC DISCOVERY. 







orally implicated in volcanic phenomena. It is to Sir John F. "W. Herschel 

 that we owe, so far as I am aware, the first suggestions of the theory of 

 volcanic action which I have here brought forward. In a letter to Sir 

 Charles Lyell, dated February 20, IS'JG, he maintains that with the accumu- 

 lation of sediment the isothermal lines in the earth's crust must rise, so that 

 strata buried deep enough will be crystallized and metamorphosed, and 

 eventually be raised, with their included water, to the melting-point. This 

 will give rise to evolutions of gases and vapors, earthquakes, volcanic ex- 

 plosions, etc., all of which results must, according to known laws, follow 

 from the fact of a high central temperature; while from the mechanical 

 subversion of the equilibrium of pressure, following upon the transfer of 

 sediments, while the yielding surface reposes upon a mass of matter, partly 

 liquid and partly solid, we may explain the phenomena of elevation and 

 subsidence. Such is a summary of the views put forward more than twenty 

 years since by this eminent philosopher, which, although they have passed 

 almost unnoticed by geologists, seem to me to furnish a simple and compre- 

 hensive explanation of several of the most difficult problems of chemical 

 and dynamical geology. 



To sum up in a few words the views here advanced. "We conceive that 

 the earth's solid crust of anhydrous and primitive igneous rock is every- 

 where deeply concealed beneath its own ruins, which form a great mass of 

 sedimentary strata permeated by water. As heat from beneath invades 

 these sediments, it produces in them that change which constitutes normal 

 metamorphism. These rocks at a sufficient depth arc necessarily in a state 

 of igneo-aqueous fusion, and then in the event of fracture of the overlaying 

 strata, may rise among them, taking the form of eruptive rocks. "Where 

 the nature of the sediments is such as to generate great amounts of elastic 

 fluids by their fusion, earthquakes and volcanic eruptions may result, and 

 these, other things being equal, will be most likely to occur under the more 

 recent formations. Proc. Canadian Institute. 



OX SOME POINTS IN CHEMICAL GEOLOGY. 



The following paper " On the Theory of the Transformation of Sedi- 

 mentary Deposits into Crystalline Rocks," has been communicated to the 

 London Geological Society, by Mr. T. Sterry Hunt, F. R. S., of the Canadian 

 Geological Commission, and is reprinted from the .Journal of the Geological 

 Society, November, 18-39, pp. 488 496. As elucidating many obscure points 

 in chemical geology, it will be read with interest. Editor. 



In considering this process, we must commence by distinguishing be- 

 tween the local metamorphism which sometimes appears in the vicinity of 

 traps and granites, and that normal metamorphism which extends over 

 wide areas, and is apparently unconnected with the presence of intrusive 

 rocks. In the former case, however, we find that the metamorphosing 

 influence of intrusive rocks is by no means constant, showing that their 

 heat is not the sole agent in alteration, while in the latter case different 

 strata arc often found affected in very different degrees ; so that fossiliferous 

 beds but little altered are sometimes found beneath crystalline schists, or 

 even intercalated with them. 



We cannot admit that the alteration of the sedimentary rocks has been 

 effected by a great elevation of temperature, approaching, as many have 

 imagined, to that of igneous fusion; for we find unoxidized carbon, in the 



