594 VOLCANIC ROCKS. 



Where volcanoes have been long extinct and 

 some of their most characteristic marks have dis- 

 appeared, similar doubts have prevailed on this 

 subject, even in a greater degree. But it will be 

 found that the chief confusion has arisen from 

 prejudices respecting the trap rocks, which some 

 of these observers have thought fit to attribute to 

 an aqueous origin. Many of the unquestionably 

 volcanic rocks, so much resemble these in cha- 

 racter, that it became necessary to deny them 

 an igneous origin also ; since that was supposed 

 to be decided by circumstances which are not 

 always present in the volcanic rocks. Hence, 

 chiefly, that incurable confusion which reigns 

 in the descriptions of writers on this subject, 

 and which the author's want of experience in 

 volcanic countries, does not permit him to elu- 

 cidate, or remove. 



That more correct theory of the trap rocks, 

 which now begins so generally to prevail, will 

 hereafter remove many of these obscurities ; when 

 unprejudiced observers, habituated to the various 

 appearances displayed by these, shall turn their 

 serious attention to the study of volcanoes. It is 



