92 Geological Results of the Earth? s Contraction. 



d. Distribution of the heat attending submarine action, causing meta- 

 morphic changes.* 



V. Earthquakes, or a vibration of the earth's crust, consequent 

 on a rupture, internal or external, and causing vibrations of the 

 sea besides other effects, (hi, 181.) 



VI. Epochs in geological history, (iii, 187.) 



VII. Courses of mountains and coast lines, and general form of 

 continents, determined to a great extent by the general direction 

 of the earth's cleavage structure, and the position of the large 

 areas of greatest contraction. 



Continents (or areas of comparatively slight contraction) often 

 therefore present ranges of mountains near their borders, and 

 these mountains are highest and abound most in volcanoes around 

 the largest ocean, (the Pacific, iii, 398.) Thus the existence of 

 such continental areas determined the existence of the mountains 

 they contain ; and also the mountains in their turn, determined to 

 some extent the position and nature of subsequent deposits form- 

 ed around them, effecting this either directly, or by influencing 

 the courses of ocean currents during partial or entire submergen- 

 ces, or by determining the outlines of ancient seas of different 

 epochs. According to this view, the general forms of continents, 

 and those of the seas, however modified afterward, were to a 

 great extent fixed in the earliest periods by the condition and 

 nature of the earth's crust. They have had their laws of growth, 

 involving consequent features, as much as organic structures. In 

 this remark, we refer not, under the term continent, to the sur- 

 faces of land bounded by the water line ; for these, by slight sub- 

 sidences, are greatly varied in form and size : — but to those ex- 

 tended areas, which, were there no water, would stand raised far 

 above the intermediate oceanic demissions. 



* In Una Journal, Vol. xlv, p. Ill, (1843,) the writer has supported the principle 

 that metamorphie changes require no other cause but what attends submarine ig- 

 neous action, and that the word hypogene applied to such rocks is inadmissible. 

 Thu views there presented properly include not only the heat from submarine vol' 

 canic action and fissure ejections, but that escape of heat, going on for ages, throng" 

 the fractures attending the gradual folding and uplifting of strata while beneath 

 the sea. Similar views, of earlier date, are offered by De la Beche, in his very 

 able Report on Cornwall, Devon and W. Somerset, 8vo, 1839. The de-bitumim- 

 zation of the anthracite coal of the Appalachians appears to be attributed by 

 Prof. Rogers essentially to this cause. (Trans. Assoc. Amer. Geol. and K**f 



1840-lri42, p. 473.) 





