INORGANIC GEOLOGICAL DYNAMICS. 605 



he says, his object is, to give an empirical repre- 

 sentation of these phenomena. In the same yeap 

 Mr. Poulett Scrope published a work in which he 

 described the known facts of volcanic action ; not, 

 however, confining himself to description ; his pur- 

 pose being, as his title states, to consider " the pro- 

 bable causes of their phenomena, the laws which 

 determine their march, the disposition of their pro- 

 ducts, and their connexion with the present state 

 and past history of the globe ; leading to the esta- 

 blishment of a new theory of the earth." And in 

 1826, Dr. Daubeny, of Oxford, produced A Descrip- 

 tion of Active and Extinct Volcanoes, including in 

 the latter phrase, the volcanic rocks of central 

 France, of the Rhine, of northern and central Italy, 

 and many other countries. Indeed, the near con- 

 nexion between the volcanic effects now going on, 

 and those by which the basaltic rocks of Auvergne 

 and many other places had been produced, was, by 

 this time, no longer doubted by any ; and therefore 

 the line which here separates the study of existing 

 causes from that of past effects may seem to melt 

 away. But yet it is manifest that the assumption of 

 an identity of scale and mechanism between vol- 

 canoes now active, and the igneous catastrophes of 

 which the products have survived great revolutions 

 on the earth's surface, is hypothetical ; and all 

 which depends on this assumption belongs to theo- 

 retical geology. 



Confining ourselves, then, to volcanic effects 



