regardmg the Rocks of ‘the Red Sandstone For^mation. 79 
that can hinder us to infer the igneous origin of the former of 
these rocks, unless the obscure position of the St Wendel pitch- 
stone. Now, were it even proved that this mass forms a short 
bed, it would only appear as a kind of stream, or a bed-like 
vein, among sandstones, in the same manner as the basalts are 
seen in streams or in bed-like veins among calcareous or argilla- 
ceous formations, in the Vicentin, Sicily, Auvergne, Scotland, 
and elsewhere. This observation is equally applicable to the 
difficulties which M. Beudant finds in the alternations of secon- 
dary basalts and sandstones. 
It is a matter of fact, that, in Silesia, in Scotland, in France, 
Germany, &c. such alternations exist; but I have already 
shown in my Essay, that these alternations are only included in 
a short space of ground, and that they cannot be observed be- 
yond certain limits. After this, one cannot but be astonished to 
find M. Beudant asserting that they pervade the whole extent 
of a formation ; whereas the fact is, that they only appear in a 
formation in the form of more or less extended and unconnected 
patches. If it be admitted by all geologists, that the face of a 
hill or a short space has often given rise to the idea of alterna- 
tions of true basaltic beds with sandstone, what geologist has 
ever been able to trace a single basaltic bed through a whole 
local sandstone formation ; and where, in the whole annals of 
science, do we find recorded a single instance of the kind ? 
Besides, on examining these very alternations, one finds that 
the number of short beds forming streams or vein-like beds di- 
minishes much, for most of them, after a scrupulous examina- 
tion, turn out to be only various kinds of veins ; for instance, 
Salisbury Craigs, Lichtenberg district, &c. ; and often the short 
beds have the appearances of those masses elevated at once from 
below, as at Stirling Castle, Perth, North Berwick Law, Edin- 
burgh &c., or the matters have extended themselves to a short 
distance from the orifice through which they were elevated. 
These appearances only present great difficulties of explana- 
tion. If we comprehend among these alternations the beds of 
wacke and of trap-tufia, we then naturally find it difficult to 
explain the igneous origin of so many beds of only a few feet in 
See Professor Jameson in Wernerian Memoirs. 
