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ascertain the exact disposition of-the mineral materials theyafford; but a circumstance cannot fail to have struck him duringthe course of his researches which opens to his view a far moreextensive and interesting field of enquiry with regard to therelations of these rocks to the general revolutions of nature; forhe will have found in many of these beds spoils of the vegetableand animal kingdom imbedded, particularly the remains ofmarine zoophytes and shells, and often in such abundance asto constitute nearly the entire mass of particular strata. Ifhe is led by the interest thus excited to examine more closelythe phoenomena attending the distribution of these remains, hewill find them as remarkable in the detail as they are strikingin a general point of view. In some countries he will perceivethat none of these remains occur (for instance in Cornwall andthe Scotch highlands), in others (as in the south-eastern coun-ties of Cnglaud) not a well can be sunk, or pit opened, withoutpresenting them in abundance ; and pursuing the enquiry, hewill arrive at the conclusion that the lowest series of rocks,which have therefore been considered as primitive, are entirelydestitute of those remains.* That the next contains themsparingly, while they abound in the three succeeding series,although not without the occasional interposition of beds in

tions, form what the Wernerians call formation suites. We may mention1st, the limestone suite ; this exhibits, in the inferior or primitive order,crystalline marbles; in the two next, or transition and carboniferous orders,compact and subcrystalline limestones (Derbyshire limestone); in the su-permedia! or floetz order, less compact limestone (lias), calcareou^reestone(Portland and Bath stone), and chalk; in the superior or newest floetz order,loose earthy limestones

2d. The argillaceous suite presents the following gradations; clay-slate,shale of the coal-measures, shale of the lias, clays alternating in the ooliteseries, and that of the sand beneath the chalk; and lastly, clays above thechalk.

3. The siliceous suite may (since many of the sandstones of which it con-sists present evident traces of felspar and abundance of mica, as well asgrains of quartz, and since mica is more or less present in every bed of sand)perhaps deserve to have granite placed at its head, as its several membersmay possibly have been derived from the detritus of that rock; it may becontinued thus; quartz rock and transition sandstone, old red sandstone,millstone-grit and coal-grits, new red sandstone, sand and sandstone beneaththe chalk, sand above the chalk. In all these instances a regular diminutionin the degree of consolidation may be perceived in ascending the series.

* Some appearances of organic remains have indeed been said to havebeen observed among primitive rocks, but they may very possibly havebeen deceptive; the only observation of this kind which requires notice isone of Dr. Mac Culloch's; that most accurate geologist describes a bed ofgryphite limestone as underlying gneiss in one of the Hebrides ; but whenthe extreme contortions of the strata of gneiss, as figured by himself, are