1816.} during the Year 1815, 65 
he is aware of the coincidence, and I have no doubt that they ori- 
ginated with himself. 
Great Britain furnishes perhaps the finest illustration of the Wer- 
nerian theory of the position of rocks any where to be found. It 
even enables us to make some additions to his series which it pro- 
bably was out of his power to discover in Germany, because the 
rocks in that country are too much covered with soil, We are en- 
abled likewise to trace the series of formations farther than Werner 
could in Germany, where the most recent beds either never existed 
or have been washed away. 
The different beds of which Great Britain is composed, viewed 
on the great scale, dip to the east or south-east; so that by travel- 
ling west we come always to older and older formations, till at. last 
in the Scilly islands, Argyleshire, Inverness-shire, and Ross-shire, 
we come to the oldest rocks of all; those which are called primi- 
tive, aud contain no petrifactions. 
The Scilly islands are composed of granite which, according to 
Mr. Majendie’s observations, appears to be stratified, There is 
likewise a ridge of granite rocks that runs from the Land’s End to 
Dartmoor, in Devonshire. On both sides of this ridge. rests clay- 
slate in regular beds. This mineral in Cornwall is called killas, 
which has been preposterously applied by some to greywacke, a rock, 
to which it bears noresemblance. The position of the rocks in In- 
verness-shire, and Argyleshire, has not been fully made out. The 
task is Herculean, and would require the assiduity and enthusiasm 
of a Saussure. But the whole country, with a few exceptions, is 
primitive, and the principal rocks in those parts of it which I have 
visited are gneiss, mica-slate, clay-slate, and porphyry. Several 
rocks occur in this district which it is not easy to refer to any 
known species. Among others, that which constitutes the summit 
of Ben Nevis. The primitive country in this northern part of the 
island extends to the east coast in_the counties of Bamf and Aber- 
deen. Further north there occur newer formations. But with this 
remote part of the island we are but imperfectly acquainted. On 
the west coast the primitive country extends to the Frith of Clyde, 
but does not cross it, It appears again in Galloway, the structure 
of which is likewise imperfectly known. It stops short again at the 
Solway Frith; but seems to re-appear in Cumberland. But this 
interesting country has never been examined by any person suffici- 
ently acquainted with the science of rocks, to be able to determine 
its structure with accuracy. It does not appear that Wales con- 
tains any primitive rocks ; though this has not been made out in a 
satisfactory manner, 
Next to the primitive come a class of rocks, called ¢ransition. 
They contain petrifactions, and are very abundant in Great Britain 
I do not know that they have been observed further north than the 
Frith of Forth. But the basis of the Pentland Hills, at least in 
some places, is a transition formation. The Lamermuir Hills-con- 
sist chiefly of greywacke and other transition rocks, and they extend 
Vor. VII. N°J, E 
