ART. IV.-1. Reports of the Board of Agriculture. London,

1796-1815.

2. Transactions-Proceedings-and Quarterly Journal of the Geological Society of London. London, 1808-1851.

3. Transactions of the Highland and Agricultural Society of Scotland. Edinburgh, 1850, 1851.

4. Report on the Geology of Cornwall, Devon, and West Somerset. By SIR HENRY DE LA BECHE, F.R.S., &c. &c., Director of the Ordnance Geological Survey. London, 1839. 5. The Nature and Property of Soils, and their Connexion with the Geological Formations on which they rest. By JOHN MORTON, F.G.S. London, 1842. Third Edition.

6. Journal of the Royal Agricultural Society of England. Vols. i-xii. London, 1840-1852.

7. Lectures on Agricultural Chemistry and Geology. By JAMES F. W. JOHNSTON, M.A., F.R.S.S. L. & E., &c. &c. Edinburgh and London, 1844.

8. Memoirs of the Geological Survey of the United Kingdom, and Museum of Economic Geology. Vol. i., Vol. ii., Parts I. & II. Published by order of the Lords Commissioners of Her Majesty's Treasury. London, 1846-1848.

9. Proposals for a Geological Survey, specially directed to Agricultural Objects. By JOSHUA TRIMMER, F.G.S. London,

1850..

10. Report on the Agricultural Capabilities of New Brunswick. By JAMES F. W. JOHNSTON, M.A., F.R.S.S. L. & E., F.G.S., and C.S. Frederickton, 1850. Second Edition.

11. Notes on North America-Agricultural, Economical, and Social. By the Same. London, 1851.

12. An Address on the Recent Progress of Geological Research in the United States, delivered at the Sixth Annual Meeting of the Association of American Naturalists, held at Washington, May 1844. By HENRY ROGERS, Professor of Geology in the University of Pennsylvania. Philadelphia, 1844.

THAT fascinating writer, the Author of the "Old Red Sandstone," has, in a recent work, compared the search of geologists for fossil fishes in the lower Silurian strata, to the labours of the patient angler, who, having cast his line day by day, into some large inland water, can scarcely detect a nibble after the lapse of months, and at the end of years cannot boast of captures exceeding a score. This analogy may even be carried further. is notorious, that among the brethren of the gentle craft, no fish are so large as those which are not brought to land, and that of

It

Recent and Remote Strata.

391

none is the weight so accurately determined. So it is in geology. We are better acquainted with the history of the strata most remote from our own times, than with the history of the period which immediately preceded the epoch of our race. We know more of what has happened in the depths of the ocean, than of events which have taken place upon the surface of the land. We have traced a long series of organic life through the many thousands of feet which constitute the mass of the Silurian strata; we can follow its migrations, and point out the direction of the currents which transported its germs; we even undertake to trace the shore of the Silurian ocean, and to indicate the position of subaerial volcanoes which scattered their ashes into the sea to form the peperinos of Snowdon. We know the feeding grounds of every shoal of fish which swam through the seas of the Old Red; we can describe the process by which the coral reefs of the carboniferous and Silurian limestones were formed; and can follow them through all their risings and sinkings. But the Geological Society has held its meetings for nearly half a century in buildings whose foundations are laid in a bed of gravel teeming with the remains of the elephant, rhinoceros, hippopotamus, and other extinct mammals. With them are associated land and fresh water molluscs, all of species now living, and with one or two exceptions, identical with species now inhabiting the banks and waters of the existing Thames; and yet it is still an open question, in the discussions of that affectionate but rather pugnacious brotherhood, whether those deposits were formed before or after the emergence of Britain from beneath the glacial sea; whether the extinct pachyderms were, during any part of their range in time, coeval with man; whether they died out, one by one, or were cut off by a series of local catastrophes, which mark a particular epoch in the history of the world. Nay more, it is not even settled as yet whether there was a glacial epoch or not; whether, after the temperate latitudes of Europe and America had been occupied by a fauna and flora, indicating a high temperature, a refrigeration took place down to that of the arctic circle; whether our present climates are tending towards their zero, or whether they have passed it, and indicate a rising of the cosmical thermometer. Even among those geologists who admit the extensive agency of ice at the close of the tertiary era, there is the utmost diversity of opinion, whether the deposits once called diluvium, and now known to many geologists by the indefinite name of "drifts," were formed by terrestrial glaciers or by shore ice, or by ice drifted from arctic lands, under climates not very different from the present; just as icebergs from Greenland and Labrador now float occasionally to the latitude of the Azores. On the other hand, there are those who abjure ice

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altogether, and with whom the transporting power is made to consist of waves of translation, travelling with the speed of a railway train, at the rate of thirty miles an hour, and set in motion by the sudden upheaval of parts of the bed of the sea, which spread over other parts of it streams of moist detritus, by which the rocks over which they passed were grooved and polished and scratched.

It is not with respect to speculative questions alone that the neglect of the geology of the surface constitutes the opprobrium of the science, and shakes the confidence of the uninitiated in the soundness of geological inductions respecting the other extreme of the series. It has operated detrimentally on its very important practical applications to the theory and practice of Agriculture. A more accurate knowledge of the superficial deposits is essential to an accurate knowledge of the nature and distribution of soils and subsoils, which, in the majority of cases, are dependent on those neglected deposits; and it would furnish an answer to the objection with which landowners often upbraid geologists, when they are sceptical as to the value of geological investigations.

It is now rather more than half a century since the cultivators of geology, abandoning mere arm-chair speculations as to the manner in which planets have been formed, applied themselves to the task of observing the structure of the earth as it exists, the materials of which its crust is composed, and the order in which these are arranged. Those who have marked the progress of the science during that period, cannot fail to have observed the numerous successful results which attended its practical application in the outset of its career, and the small number which have been achieved since it advanced beyond its robust childhood. In an Article in this Journal on the Memoirs of William Smith,* we enumerated some of these triumphs of applied geology. We are unable to call to mind more than two subsequent attempts to direct the study to similar objects of practical utility. One of these was the inquiry by the Commission with Sir Henry De la Beche at its head, respecting the best building stone to be used for the New Palace at Westminsterand even with that Smith was associated; the other was the discovery of the black-band ironstone by Mr. Mushet, to the great benefit of some landowners and iron masters in Scotland. What has been the cause of the exuberant harvest yielded by applied geology at one period and its poverty at another? Is the soil exhausted, or has its cultivation been abandoned? An answer may be found to these questions in the fact, that the early vota

* See North British Review, No. VII.

History of Agricultural Geology.

393 ries of geology were practical men, and gave their researches an economic application-Werner to mining-Smith to mining, general engineering, and agriculture. Their successors have been philosophers and naturalists, whose favourite lines of research have been questions in geological dynamics, and in the ancient natural history of the earth. When practical men shall again become geologists, we may hope to see geology once more applied to practical purposes, as well as advanced in a more comprehensive point of view. The Government School of Mines promises to rear a race of future superintendents of mining operations who will make this use of the science which they acquire. For the instruction of the still more important agricultural class, no such public provision has yet been made, though the annual value of the agricultural produce of Great Britain is ten times that of its mines; and till the agricultural class shall have somewhat more largely imbibed the streams of science, we cannot expect much progress to be made in agricultural geology.

With Agriculture were connected the first efforts of Geology as a science of observation. In treating of the agriculture of any district, it is necessary to describe the areas which are occupied by different kinds of soil, rendering necessary the adoption of different systems of husbandry. In districts (of which Britain contains several) where the superficial deposits are either generally absent or only slightly developed, the variations of soil correspond more or less with the outcrops of the strata. The areas which these occupy were known long before it had been ascertained that they were the results of stratification and denudation. Hence we find, that so early as 1734, the outcrops of the strata of Kent-one of the districts least covered with the superficial deposits had been described by Parke, in a treatise on the agriculture of that county, in such a manner as to render easy the subsequent construction of a geological county map. Hence we find Marshall, in describing the practice of agriculture in Norfolk in 1782, entering into disquisitions essentially geological; and hence it is that to the Board of Agriculture belongs the honour of having produced the first geological map of any part of England. Its first series of reports contains, on the testimony of Conybeare, very adequate geological maps of the North Riding of Yorkshire, of Derbyshire, and Nottinghamshire, with a less accurate map of Devonshire. The report on Kent in 1796, and Maton's tour through the south-western counties, both contain geological maps of the districts described; and between that date and 1813, the same Board had given useful maps of Surrey, Berks, Bedford, Gloucester, Wilts, Lincoln, Durham, and Cheshire, besides publishing a second report on Derbyshire, by Farey, exclusively devoted to its mineralogy. Farey was a pupil of Smith; and several of the second series of the Board's

reports were drawn up by those to whom Smith's discoveries had been orally communicated. In 1790, he had commenced his investigations of the succession of strata. Ten years later he published a work on the same subject; and in the meantime manuscript copies of his Tabular View of the Strata and their Organic Contents were in circulation both in Britain and on the ContiIt was not till 1815, after many delays, that his map of England and Wales made its appearance; but the manuscript had been, in great part, prepared before those local maps of the Board of Agriculture, which are certainly the earliest published geological maps of any part of these islands.

The progress made in the science of geology by Smith's discoveries of the laws of stratification, and of the distribution of their organic remains, has perhaps tended to retard, for a time, its application to agriculture, by giving an undue importance to the theory of the substratal origin of soils, and by leading geologists away from practical investigations.

It was natural, too, that "Strata Smith" should be led, in his agricultural investigations, to take an exaggerated view of the connexion between the soil and the strata to which he owed his celebrity; and that having devoted a large portion of his attention to the study of oolitic districts, in which soils prevail which have been derived exclusively from the subjacent rock, he should have been led to draw conclusions too general from local phenomena. The construction, moreover, of geological maps, even of those on the largest scale yet constructed, renders necessary the adoption of a geological fiction. In order to represent the outcrops of the strata, it is necessary that all the superficial deposits should be supposed to be removed; and that the rock below them, which is nearest to the surface, should be assumed as the surface. It becomes necessary also to sink the mineral distinctions of the strata, and to include under one colour, a group of strata connected by the presence of a common group of fossils, however numerous may be the alternating silicious, argillaceous, and calcareous strata of which the group consists. To an assumption that soils are exclusively derived, not only from the strata immediately below them, but from those strata as represented on geological maps, the transition is so easy, that it would have been marvellous if it had not been made. From ignoring the geology of the surface on geological maps, we proceeded to ignore it in nature, and to treat of agricultural geology in the spirit of the strolling players who performed the tragedy of Hamlet with the part of Hamlet unavoidably omitted. The cultivated soil rarely exceeds a foot in depth, and is frequently much shallower. There are few operations of agriculture in which the subsoil is of much importance at a greater depth than seven feet. The instances are rare in which mineral manures are