efficacious in the field than they are in daily intercourse of business and society.

Homeward, and laden with his fossil treasures, the student has still new phenomena to observe and new lessons to learn. The clear relief in which the lowering sun has thrown every knoll and crag, every glen and gorge of the distant hillside, explains to him more clearly than words the agencies of waste and denudation-of frost and ice, of rill and runnel—to which it has been successively subjected. The rounded knoll (roche montonnée) bespeaks the grinding of the ice-mass, the crag with its shingly talus, the action of frost and rain, the gorge the power of running water, and the broader glen, with its occasional crossmounds, the score and grind of the retreating glacier. The long ages of waste and denudation to which that hill-range has been subjected as it has alternately sunk beneath the sea and emerged again into the atmosphere, are unveiled by that sunlight in a way that leaves no room for doubt, and renders every feature of the easiest recognition. And thus, where others would "homeward plod their weary way," the field-geologist has his thoughts carried away from the present into the far-distant past-gleaning a new fact in world-history at every turn, and calling up vanished aspects of sea and land by the magic wand of scientific deduction. The scenery of nature which, to most observers, is a mere passive circumstance and nothing more, is to him a thing instinct with a thousand activities and producing causes; and what in them is a mere transient gleam of admiration, becomes in him an enduring glow of the clearest understanding.

Oh the delight of the young geologist as, seated on some craggy peak, he looks down on the hills and glens and valleys that surround him! It is not alone the presence of their beauty or wildness or grandeur that strikes him as it

must strike other observers, but the conscious knowledge of the agencies by which their aspects were produced, and the looking backwards in time through the long ages of change to which they have been subjected. That hillside smoothed and rounded by the ice-sheet, that glen, with its lateral and terminal moraines gouged out by the glacier, and that winding valley eroded by aqueous and meteoric action, is each graven with a history which speaks to the eye of science, and makes these mountain solitudes rife with the presence of nature's powers and activities. To others it may be given to admire, to the geologist it is given to comprehend, and in that comprehension to enjoy the purest pleasure which a survey of the phenomena of nature can convey. "To sit on rocks, to muse o'er flood and fell," may be a joy to the poet and painter; but to know how that rock was formed, to trace that flood through its previous workings, and to connect that fell with all its former associations, is a nobler and more soul-inspiring delight, and one which none save the earnest student of nature can ever hope to achieve.

It is thus in the field that the student of geology obtains his fullest and newest information, collects additional stores, and corrects former misconceptions. A day well spent in the field is worth a dozen of reading at the fireside, the while that its bracing exercise paints the cheek with a ruddier glow, and confers fresh strength on the worker. As geology is primarily a science of observation and description, the field is its proper arena, and no one will ever arrive at true conceptions of world-history unless through the immediate study of the leaves on which that history is recorded. Travel and observation are the prime essentials of the science, and he who forgoes these, to the extent of his opportunity, omits the main chance of understanding aright its

numerous and complicated problems. "To the field on every fitting occasion," should be the guiding maxim of the young geologist; and though new discoveries may not always reward his toil, though he should even fail to obtain what others have obtained before him, he is at least in the way of doing both, and in the excellent practice of training his powers of observation. And when his day's work is done, however little it may have added to his scientific stores, he has secured one luxury at least by his twenty miles' ramble in the pure country air—a blessing which comes to the poor unasked, and which the rich but too seldom enjoy the luxury of feeling tired.

SCOTTISH GEOLOGY-ITS PROOFS

AND PROBLEMS.

By the proofs of Scottish geology we mean what is known, or at least generally admitted, by competent observers; and by its problems, what is still doubtful, and requires further investigation. Our object in the present paper is not to sketch the history of Scottish geology, which about the beginning of this century was an inextricable labyrinth of theories and disputations between "Neptunists and Plutonists," and which at a later period was little else than a bald nomenclature of rocks and minerals;* but simply to try to distinguish between the established and the doubtful, that the student may better know what to accept, and where to direct his investigations. And yet, while alluding to the history of Scottish geology, one cannot avoid mentioning the names of such men as Hutton, Playfair, Ure, Hall, M'Culloch, and Jameson, as contributing largely, even

*This was the grand epoch of rock and mineral collections, the age of magnificent cabinets filled with rocks, minerals, and cut gems-the arranging of these into groups, and genera, and species (after the systems of botany and zoology), being the minute but futile labours of the collectors. A knowledge of Lithology and Mineralogy is no doubt indispensable to the study of Geology; but the idea of dealing with mixed rocks as with mineral, vegetable, and animal species, was a fancy that retarded rather than accelerated the progress of the science.

amidst these unproductive discussions, to the substantial progress of the science. Geology, such as we now understand it, can date back little more than forty years; and during this period its advancement in Scotland has been indebted in no small degree to the labours of M'Culloch, Jameson, Fleming, M'Laren, Cunningham, and Hugh Miller, and especially to those of Lyell, Murchison, Nicol, and others, who are still steadily endeavouring to unravel its many complicated physical as well as paleontological problems. Our present purpose, however, is not the history but the facts of the science; a brief indication, for the guidance of the young geologist, of what is already established, and of what remains doubtful, and to the elucidation of which he could with advantage direct his observation. In a field so vast, and where the labourers are so few, it is ever of importance that the new-comers, instead of treading in the old beaten tracks, should have their attention directed to the determination of the doubtful and the discovery of the unknown.

If the student will turn to any of the geological maps of Scotland-M'Culloch's, Nicol's, or Knipe's-he will find that the various rock-formations have all a south-west and north-east strike, with their dip to the south-east-thus placing the older rocks to the north-west, and the younger, in regular succession, to the south-east. The same holds good in England, so that a line drawn from London to North Wales would pass in succession through all the formations from the Tertiary to the Cambrian, just as a line drawn from the Firth of Forth to Cape Wrath would pass through the upper coals on through all the underlying for mations to the Lower Laurentian. This fact is of use as stratified systems-the

affording a sort of index to the traveller passing from younger to older if he begins at the south-east, and the reverse, or from older to younger, should