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8 Principles of Geology. 
oolite, calcareous grit, Oxford clay, Kelloways rock, cornbrash, the 
Bath oolite rocks, lias, red marl and sandstone, magnesian limestone, 
coal series, mountain limestone, and slate rocks. The series in the 
south of England is precisely accordant, except that the magnesian 
limestone is there deficient, and that the Kimmeridge clay is covered 
by some strata which do not reach into Yorkshire. Besides, we find 
the Yorkshire strata actually united with those of the same name in 
other parts of England, so thati there can be no doubt of the gen- 
eral continuity of the strata, and of constancy in their order of suc- 
cession. ‘The same conclusion is upheld by independent research in 
foreign countries. There, as in England, it is demonstrated, that, to 
as great a depth as can be accurately examined, various rocks are 
laid on one another, in a certain consecutive series, by which it is not 
difficult to assign to each its unvarying place in the scale; and that 
these rocks are not formed in semlasen patches, but in swidely-ex- 
tended strata, which hold their 1kingdoms. : 
This encourages us to inquire whether there be not some general 
analogy of the rocks, not only across islands and kingdoms, but even 
across whole continents ; for if this should prove to be the case, we: 
shall be enabled to propose general laws of structure, applying equally 
to every part of the globe. For the purpose of this comparison, we 
must not think to employ the characters of individual rocks, however 
remarkable they may appear, but we must group together analogous 
formations, and look only on the greater features of nature. We 
must consider the physiognomy of the earth, and, amidst many local 
variations, trace lines of general agreement. 
Reviewing the series of British rocks, we shall observe three ere 
perhaps, quite as definite characters, but they are not manifested 
without more research. € mountainous regions of Britain are 
composed of hard, often crystallized rocks, variously associated and 
related to one another, commonly stratified at high angles of declina- 
tion, and for the most part destitute of organic remains. Such are 
granite, gneiss, mica slate, quartz rock, primitive limestone, serpen- 
tine, and slate. From the Shetland Isles to Cornwall, a general con- 
formity in character unites the mountain groups. From these eleva- 
tions, the rocks above-named dip or decline on all sides into the earth, 
sink deep under the more level regions, and are there covered up 
and buried beneath various deposits of limestone, sandstone, coal, 
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divisions, of which two are extremely obvious; the rocks of the — 
mountains and the strata of the plains: the third division possesses, 
