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CHAPTER XXIII. 



IGNEOUS CAUSES. 



CHANGES OF THE INORGANIC WORLD, CONTINUED — IGNEOUS CAUSES — DIVI- 

 SION OF THE SUBJECT —DISTINCT VOLCANIC REGIONS REGION OF THE ANDES 



— SYSTEM OF VOLCANOS EXTENDING FROM THE ALEUTIAN ISLES TO THE 

 MOLUCCA AND SUNDA ISLANDS — POLYNESIAN ARCHIPELAGO — VOLCANIC RE- 

 GION EXTENDING FROM CENTRAL ASIA TO THE AZORES TRADITION OF 



DELUGES ON THE SHORES OF THE BOSPHORUS. HELLESPONT, AND GRECIAN 

 ISLES — PERIODICAL ALTERNATION OF EARTHQUAKES IN SYRIA AND SOUTHERN 



ITALY WESTERN LIMITS OF THE EUROPEAN REGION EARTHQUAKES RARER 



AND MORE FEEBLE AS WE RECEDE FROM THE CENTRES OF VOLCANIC ACTION 

 — EXTINCT VOLCANOS NOT TO BE INCLUDED IN LINES OF ACTIVE VENTS. 



, 





We have hitherto considered the changes wrought, since the 

 times of history and tradition, by the continued action of 

 aqueous causes on the earth's surface ; and we have next to 

 examine those resulting from igneous agency. As the rivers 

 and springs on the land, and the tides and currents in the 

 •sea, have, with some slight modifications, been fixed and 

 constant to certain localities f 



om 



the earliest periods of 

 which we have any records, so the volcano and the earth- 

 quake have, with few exceptions, continued, during the same 



But as there are 



»Teat power 



lapse of time, to disturb the same regions. 



signs, on almost every part of our contineir 



having been exerted by running water on the surface of the 



land, and by waves, tides, and currents on cliffs bordering 



the sea, where, in modern times, no rivers have excavated, 



der mined 



so we find signs 



of volcanic vents and violent subterranean movements in 

 places where the action of fire or internal heat has long been 

 dormant. We can explain why the intensity of the force of 

 aqueous causes should be developed in succession in different 

 districts. Currents, for example, tides, and the waves of the 



