Dr Boue on the Volcanic Rocics of France and Scotland. 327 
of that country, I now send you a few notes of my observa- 
tions, expecting at some future period to extend and illustrate 
them more fully and accurately than I can spare leisure for at 
present. In making you acquainted with some of the geo- 
gnostical phenomena I met with, probably a sufficiently intelli- 
gible mode will be to institute a comparison between the rocks 
of the districts in question, and those that occur in Scotland, 
particularly in the .vicinity of Edinburgh. 
1. Between Edinburgh and Glasgow, near Calder, there is a 
quarry of a black compact basalt, which contains grains of oli- 
vine and crystals of augite. This rock cannot be distinguished 
from the basalt of Montaudoux, near Clermont, in Auvergne * *. 
This small hill is considered by Montlosier, Raymond, Lacoste, 
&c. as part of a very ancient stream of lava, (coulee,) and is 
intimately connected with other masses of ancient volcanic for- 
mation. 
2. At Apchon there is an alternation of basalts, tuffas, and 
lithomarges : These various substancfes and their arrangements 
are much the same as what occur at the Giant’s Causeway in 
Ireland, and yet here, according to geologists, the whole series 
is of volcanic formation. 
8. The porphyry-slate on the north-west borders of the Mont 
d’Or, which is of a volcanic nature, bears a striking resemblance 
to that of the Island of Lamlash, in the Frith of Clyde. The 
same is the case with the porphyry-slate of the Mezen, and of 
other parts ; and it is worthy of remark, that these rocks in France 
pass into trachyte or volcanic porphyry, and sometimes contain 
fragments of undoubted scoriae. The rock of the Dalmahoy 
Hills near Edinburgh, has the same basis as the volcanic por- 
5'ocks of Mont d’Or, and like them contains acicular 
and large crystals of felspar and crystals of augite. The por- 
phyry-slate of North Berwick Law, and of Traprain Law, re- 
sembles the porphyries of Mezen and Mont d’Or, but the re- 
cur trap-rocks. Another of my pupils Dr Daubeny, also distinguished for hfs 
aotivity and intelligence, and who has examined much of Scotland, has lately 
spent some time in Auvergne, and will, I trust, soon favour us with an account of 
his observations. Dr Ogilby, one of my early pupils, now in France, will also visit 
Auvergne. r. j. 
* Buch’s Geognostische Beobachtungen, &c. T. p. 235. 
