332 ON THE INFORMATION OF tiOCK?. ' ^ [August, 



tlie other detaclied masses of rocks of a similar origin. 

 Great care ought to be taken to fill up tlie chasm that 

 time has made in the continuity of the rocks^ before 

 we can decide with propriety. 



The fields of extinct volcanoes, that I have had an 

 opportunity of examining, were as similar as possible 

 in their component parts, and relative position : an 

 extensive field round Orlot — near Humila, and at the 

 Cape du Gat in Spain — round Rome — between Rome 

 and Florence, and in the Vincintin, in Italy — in Au- 

 vergne, in Fraace^ — round Andernack on the Rhine — 

 at Cassel in Germany — all of which leave no doubt 

 in my mind of their volcanic origin. In all of them I 

 found abundance of basalt ; in somo of them the great- 

 est part of the solid Lavas were in form of basalt. The 

 Austrian police prevented me twice from examining 

 Hungary, but I have seen repeated collections of the 

 rocks of that country, and could Scarce distinguish 

 them from those collected from around Naples. How 

 ilie origin of basalt could be doubtful with the Werne- 

 «'ians, can only be accounted for, by Werner having at 

 first ptit the detached masses of basalt, foimd in Saxo- 

 3iy, into the Neptunian origin, and that his disciples 

 have since persevered in the arrangement. 



In geological descriptions, it is probable that much 

 confusion has arisen from mistaking veins for beds. 

 A bed is a stratum in a stratified rock ; but rocks that 

 nre not stratified cannot be said to contain beds : they 

 fnay have some of their vertical fissures filled with dif^ 

 ferent substances, or a crack or split in the rock filled, 

 jjp by infiltration, but that I should suppose W9^)d be,. 



