\ 
487. 
formation. The suggestion was adopted by Mr. Murchisen and Pro- 
fessor Sedgwick in 1839, and at once shed forth a new and brilliant 
light that has rapidly dispelled the darkness in which the slate rocks 
of this extensive formation had, until this discovery of Mr. Lons- 
dale, been involved. The first application that was made of this 
new instrument of identification to the continental rocks led to the 
immediate solution of the difficulties that had attended the attempts 
of preceding observers to ascertain the equivalents of the English 
series in the districts adjacent to the coal-fields of Liége and in the 
Bas Boulonnais; and we have already noticed the vast extent to which, 
during the past year, a similar identification has been carried in the 
Rhenish provinces and in Russia. 
We should, however, not forget, that, by the recent examination 
of Russia, the distribution of fossil animals has been found to be 
materially connected with mineral conditions; for Mr. Murchison 
and M. de Verneuil have shown us, that with the resumption of its 
red and green characters, the vast Old red system of that empire 
resumes the very same zoological types as in the North of Scotland. 
A short time will probably produce an abundant recognition of 
the same palzozoic classification in America, We have long been 
learning an instructive lesson as to the comparatively small value of 
mineral character in determining the age of strata, where there is 
no opportunity of appealing to the test of superposition ; and organic 
remains have been found to supply the surest and safest criterion 
whereby formations can in such cases be made out; thus, the evi- 
dence of fossil shells has recently enabled us to identify the Oolite 
formation in Cutch and the deserts adjacent to the Indus, and on the 
Tartar side of the Himalaya Mountains. Cases of this kind teach 
us to appreciate even still more highly than we have been wont to 
do, the paramount value of Paleontology in determining geological 
equivalents. 
} ORIGIN OF COAL. 
In the early part of last year some very interesting papers came 
before us tending to throw light on the obscure and difficult ques- 
tion of the formation of coal. 
Mr. J. Hawkshaw, having communicated to us in June 1839 a de- 
scription of several large fossil trees found in a cut on the Bolton Rail- 
way, near the Dixon-fold Station, five miles and a half N.W. of Man- 
chester, standing immediately upon a thin bed of coal perpendicularly 
to its surface, has added a statement of further facts, confirming his 
opinion that these trees grew in the place and position where they are 
now found. His reasons are grounded on observations he made near 
the shores of the Caribbean sea, on the rapid decomposition of the 
trunks of solid dicotyledonous trees in hot and moist climates. This 
decomposition in a few months entirely destroys the timber, leaving 
only the bark unbroken and hollow, like an empty mould in a foundry ; 
the form of this bark remains perfect after the interior is reduced 
to dust. He infers from this example, that it does not follow that 
fossil trees in the coal formation were originally hollow because we 
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