PART I.

OUT-OF-DOOR WORK.

CHAPTER II.

FIRST ESSAYS IN FIELD-WORK.

THE direction in which the first essays of the observer in the field should be made, must depend mainly upon the nature of the district in which he finds himself situated. Under the most unfavourable circumstances, as for instance in a wide cultivated plain, with not a single quarry or natural opening to show even the nature of the formations underneath, he may nevertheless discover something to engage his attention. Thus, he may find useful employment in watching the operations of the streams which flow sluggishly through his neighbourhood, their meanderings and the efforts they make to straighten their courses, their varying quantity of mud, the effects of floods, the evidence of successive deposits, and heightening of the flood-plain. But it will seldom happen that he cannot in some way gain access to the geological formations below the surface, and even in a flat and featureless region obtain a series of facts which will

enable him to reason as to the history of the region, and to decide whether the plain has been formed by the stream, or on the floor of some ancient lake, or perchance on the bed of the sea.

Where, however, numerous openings, either natural or artificial, expose the strata underneath, the observer need be at no loss for abundant material for profitable field work. Should some of these strata be eminently fossiliferous, that is, crowded with the remains of once living plants or animals, they will almost certainly attract his earliest attention. Probably in the majority of cases men have been led to the study of geology by first becoming interested in the organic remains which they could collect for themselves, carry home as "specimens," and afterwards thoughtfully question as to their structure and history. No doubt the mere gathering of the fossils is the first and final achievement of a very large proportion of enthusiastic beginners. Even, however, if the pursuit has had no other advantage than that of affording ample exercise in the open air, it is perhaps not less beneficial than many of the time honoured forms of out-of-door recreation.

But a man may gain much more than healthful amusement from fossil-hunting. He begins, let us suppose, by trying to get hold of as many varieties, and as perfect specimens as he can find by the most patient search. But the mere pleasure of the pursuit soon begets a desire to know more about the fossils. If they are plants, the collector strives to ascertain their names, and may be content perhaps if he can write upon them their proper Latin or Greek appellations. Possessed, however, of a real desire for knowledge, he seeks to ascertain what are their

affinities with the living vegetation of to-day. By reading, by visiting museums, and by careful observation along the hedgerows or in botanic gardens, he endeavours to realize what the leaves and stems, which he finds in the solid stone, really were when they waved bright and green in the air long ages ago. The information he can glean

as to their probable botanical grade and habit, leads him to re-examine, with greater care, the circumstances under which they lie in the rock. He finds, perhaps, that they occur more particularly in one stratum, which we shall suppose consists of thin leaves or laminæ of a kind of hardened clay. It is on splitting up these laminæ that he unfolds the fossil plants. Each layer seems entirely covered with impressions of leaves, stems, fruits, or other parts of the ancient vegetation; but the fossils are all fragmentary, though well preserved. They remind him of the sheddings of trees after some early autumnal frost; the fine layers of hardened silt, on which they lie, recall the laminæ of mud which he has observed in the bottom of a pond or dried-up pool; and in the end, he concludes with some confidence that his fossil-bearing stratum was once the floor of some inland sheet of water, into which the leaves of the neighbouring woodlands were periodically shed. If he has ascertained that the plants are more nearly allied to those of a warmer region than the vegetation now flourishing in the locality, he allows himself to speculate on the probability that a warmer climate once prevailed in his own country.

The remains of animals, however, are immensely more abundant among the rocks than those of plants. The observer is much more likely, therefore, to begin by lighting upon some stratum full of shells, crinoids, corals,

or even with bones of fishes, and perhaps of reptiles. If he is not satisfied merely with forming a collection of these remains and having them rightly named, but wishes to learn what they have to tell him about ancient types of life and old conditions of physical geography, he addresses himself to the task by endeavouring to find the nearest analogies in the living world to the fossil forms which he has disinterred from the rocks. Patiently he tries to reconstruct the skeleton of which he has found the scattered bones. He learns to recognize the fragment of a shell or other fossil, and can assign it to its place in the complete organism. While the structure and zoological relations of the fossils afford him inexhaustible stores of employment, he cannot shut his eyes to the circumstances in which these fossils occur, and to the light which they cast on the history of the rocks. Corals, crinoids, and marine types of molluscan life bring before him an old sea-floor, and though the locality where his leisure hours are thus sedulously spent may now lie far in the heart of a country, with venerable trees and hedgerows, old farmsteads and roads, all bearing witness to the peaceful cultivation of centuries, the sight of that rock with its crowded fossils is as sure evidence of the former presence of the sea over the whole landscape, as if he heard there even now the murmur of the waves.

But the observer's lot may be cast in a district where no fossils are to be found. There may be nothing in the rocks themselves to attract notice, nothing likely to inspire a taste for geology or to furnish nutriment for a taste already existent. It is remarkable, however, in what apparently unfavourable circumstances an appetite for

scientific pursuits can not only exist but flourish. Let us suppose that the district in question consists of stratified rocks, like sandstones and shales, and that these strata are exposed to view in numerous quarries and natural sections. The varying composition of the beds, their order of succession, their changes in character as they are traced over the country, their influence upon the contour of the ground, the glimpses they afford of an ancient geography very different from that of the district to-day, and the manner in which they have been tilted up, curved, and broken since the time of their original formation-these, and a thousand other particulars, will eventually give even barren and seemingly repulsive rocks a charm which the richly fossiliferous deposits of the observer's later experience may never possess. If, on the other hand, the rocks are crystalline -granites, schists, and other similar masses, or basalts, tuffs, and other volcanic accumulations, the geologist, who begins work among them will almost of necessity devote himself to the mineralogical and structural side of the science. He may be first attracted by pretty minerals, -sparkling felspars, well crystallized and variously coloured quartzes, glittering micas, and many more. And doubtless the temptation to collect them, if it once arises within him, will not be likely to diminish, so long as his taste for geological pursuits lasts, and as he finds himself face to face with the minerals in the field. Pursued not as the hobby of a collector, but as an important branch of the sciences which deal with the architecture of the globe, mineralogy becomes a singularly fascinating study. I shall have occasion in later chapters to allude to some of its attractions. Should the observer be led from the