EFFECTS OF EARTHQUAKES. 



former are incomparably greater than of the latter ; but it may be 

 imagined that at earlier epochs, when the solid crust of the earth 

 was much less thick, the internal heat produced upon the sur- 

 face a much more powerful effect; so that the climates of all 

 parts of the globe must have been much more elevated than at 

 present. Numerous effects compatible with this reasoning have 

 been discovered by the researches of geologists. Thus, the 

 organic remains of animals and plants found in the sedimentary 

 strata deposited at earlier epochs in the growth of the globe, are 

 such only as could have lived in climates of a much more elevated 

 temperature, than those which now characterise the latitudes in 

 which they are found. Thus, the fauna and the flora (terms 

 adopted by naturalists to express the entire collection of animals 

 and plants existing in any place) prevailing in high latitudes at 

 remote epochs, were such as could 'exist at present only within 

 the tropics. 



110. The alternate upheavings, depressions, disruptions, and 

 dislocations of the crust of the earth assumed by geologists in 

 their explanation of the phenomena are still exhibited, though 



on a much smaller scale, in the phenomena attending earth- 

 quakes. These effects have been so fully explained in our Tract 

 on " Earthquakes and Volcanoes,'* that little need be added to 

 what has been there stated. As these phenomena are mani- 

 fested at present, they are most frequently more or less local, 

 though sometimes their effects are spread over little less than 

 an entire hemisphere. The earthquake which took place in the 

 island of Ischia, on the 2nd of February, 1828, was not felt 

 in the slightest degree either in the neighbouring isles or upon 

 the Continent ; while that of New Grenada, which took place on 

 the 17th of June, 1826, exercised its influence over many thou- 

 sand square miles. The earthquake which commenced in Lisbon 

 in 1755, and which has been fully described in a former Tract, 

 -extended in one direction to Lapland, and in the other to Mar- 



87 



