iz Scientific Reviews. 
formations from their oryctognostic differences, and would induce 
error into the science. 
'. We will continue with the county we have got into, as we be- 
lieve it was there where Professor Buckland obtained his data for 
some part of his geological equivalents, (On the Structure of the 
Alps, and their Relation with the Rocks of England, 1621,) and 
which have been transferred into the ‘“ System” of Dr. Ure, and 
form the basis of his classification. 
The members of the greywacke formation, constitute some barren 
tracts in North Wales, ranges of hills south of the Malverns, and 
some isolated hills, as May Hill, Gloucestershire. The conglome- 
rates which form the remarkable scenery of the banks of the Wye, 
of Tintern, and Chepstow, have been considered as belonging to the 
old red sandstone, on which reposes the mountain or carboniferous 
limestone, supporting the coal basin of Coleford and the Forest, in 
which the measures all dip towards the centre. Beyond, to the 
north-west, associated with the greywacke of Mitchell Dean, lies a 
band of transition limestone, of different character, and with diffe- 
rent organic remains. Whence comes it, then, that the Professor, 
in p. 104, opens his chapter on limestone, by stating that the tran- 
sition limestone of the Wernerian school, appears to be the same 
with that usually called mountain limestone by English geologists ? 
The idea given of old red sandstone is not correct. It does not 
“* accompany,” but lies under the coal depesits ; and its situation 
is not “ upon the lowest secondary rocks,’ being itself the oldest 
and lowest of that order. On what authority, also, does Mr. Brande 
state the sandstone of Hawthornden to be red marl ? 
Between the new red sandstone with saliferous deposits, and the 
Jura limestone, we have two formations a-wanting in England,— 
the muschelkalk and the quadersandstein,—and they are conse- 
quently unnoticed in the two elementary works before us. 
A distinction may be immediately perceived between the practi- 
‘eal geologist and the historian of the science, by the manner in 
-which the latter details the succession of formations, where he inva- 
‘riably omits the description of those beds apparently incongruous in 
structure with the mass of the formation, but whose occurrence be- - 
tween beds of the same nature, serve to mark the different dates 
of their deposition ; and thus in the long series of rocks, assemblages 
of monuments ef different epechas, from the first dawn of organic 
life on the globe, to the appearance of fragmentary rocks, and to 
‘the catastrophes which buried ancient vegetation and the first forms 
of animal life, we pretty constantly have sandy, calcareous, or 
-argillaceous beds, mostly formed by mechanical sediment, separat- 
‘ing the members of the same series, which would otherwise lie in 
opposition. Thus it is that in the complicated deposits of the 
‘oolites, or Jura limestone, the different beds could scarcely ever 
‘be recognized without a minute study of the fossil remains, and 
the oryctognostic characters of the intervening sands and clays. 
~ From the description given of the tertiary formations, a series of 
