[ 4^1 ] 
Other balaltic groups, are the moft common. The natu- 
ral pofition of thefe columns, whether facing the rock, 
or about the bottom of it, is moflly perpendicular. Ano-* 
ther adjacent portion of this rock is alfo charadterized by 
angular and, as it w^ere, winding fomew^hat re- 
fembling the bending pillars of Staffa, as may be obferved 
in the drawing. The rock itfeif is alfo compofed of an- 
gular maiies, as are indeed moft granites; and thefe 
malles are alfo ranged perpendicularly. Several emerge, 
as it wxre, from the tops and lides of the neighbour- 
ing rocks and hills, like fo many {lately and artificial pil- 
lars. The winding Jirata before mentioned are ahb pa- • 
rallel with each other, as 1 have frequently obferved in 
other granites, as well as common vulcanic Jirata in ge- 
neral, particularly of the harder fort, desmarest calls 
the latter Bafaltes en tables (o ; w^hich is a kind of vulcanic 
Hate, formed in parallel Jirata of different thicknefs, from 
two or three to five and fix inches. This is very common 
in the provinces of Velay and Auvergne, in France, where 
it is alfo ufed for coverings of houfes. The fame fort of 
Hate is likewdfe common to the mountains of Genoa, many 
of which feem to be of vulcanic origin, as I recoiled: to 
have remarked in pafling the chain of the bochetta^ be- 
tween Genoa and the plain of Lombardy. I m.ention this 
circumftance, as the vulcanic pheenomena of that part of 
Italv have not hitherto been attended to. In fad, it is 
lately only that fuchobfervations begin to be made in other 
countries; the charaders of extind volcanos or vulcanic 
(c) Encycloprdie, Art. Pave des Giants. 
trads, 
