786 Transactions of the American Institute. 



little doubt that they have a common origin, and, as has already been 

 observed, it is their function to counteract the leveling effect of water, 

 partly by heaping up new matter in certain localities, and partly by 

 deepening one portion, and forcing out another, of the earth's 

 envelope. It remains to see in what manner this is done. 



In a paper as profound in its views as it is luminous in its state- 

 ment. Sir John Herschel has indicated the philosophy of these 

 divulsions and upheavals, and we cannot do better here than epitomize 

 his statement. The land, as has been seen, is perpetually wearing 

 down, and the materials are being carried out to sea, thinning toward 

 the land, and thickening over all the bed of the sea. What must 

 happen ? If the continents be lightened, they will rise ; if the bed 

 of the sea receive additional weight it will sink. It is impossible but 

 that this increase of pressure in some places, and relief in others, 

 must be very unequal in their bearings ; so that at some place or other 

 this solid floating crust must be brought into a state of strain, and if 

 there be a weak or a soft place, a crack will at last take place. When 

 this happens, down goes the land on the heavy side, and up on the 

 light side. This is exactly what happens in earthquakes. We should 

 naturally expect that such cracks and outbreaks would occur along 

 those lines where the relief of pressure is the greatest, and also its 

 increase on the sea-side ; that is to say, along or in the neighborhood 

 •of the sea-coast, where the destruction of the land is going on 

 with most activity. Now, it is a remarkable fact in the history of 

 volcanoes that there is hardly an instance of any active volcano at 

 any considerable distance from the sea-coast, while it is to be 

 observed that the favorite sporting places of earthquakes are the 

 regions covered by the great chains of volcanic cones. 



That earthquakes operate to raise the land-masses is not a mei'e 

 matter of speculation, but a fatjt of repeated observation. In 1822, 

 in a single night (Nov. 19), tlie whole coast line of Chili for a hundred 

 miles about Valparaiso, with the mighty chain of the Andes, was 

 hoisted at one shock from two to seven feet above its former level, 

 leaving the beach lelow the old low-water mark high and dry. In 

 1819, in an earthquake in India, in the district of Cutch, bordering 

 on the Indus, a tract of country more than lifty miles long and sixteen 

 broad was suddenly raised ten feet above its former level. And again, 

 in 1538, in the convulsion which threw up the Monte Nuovo, the 

 whole coast of Pozzuoli, near Naples, was raised twenty feet above its 

 former level, and remains so permanently upheaved to this day. 



