The inferences derived from these and similar observations made on the phenomena of peat bogs and their buried forests in many other parts of Scotland, are somewhat conflicting. There can be no doubt that the climatal conditions that permitted oaks to grow on the higher slopes of the hills in the north of Scotland, as well as trees of considerable size in the Orkney and Shetland Islands, where scarcely a stunted shrub is now to be seen growing in a wild state, were more favourable to the growth of forest trees than those which now prevail. On the other hand, the large pines found in some of the Lowland mosses would seem to indicate a colder climate. The probable explanation of this is, that the pines and oaks belong to different periods of time, that the former preceded the latter and flourished when Scotland stood higher above the level of the sea, and, being thus more extensive, was under a colder climate, somewhat analogous to that which now prevails in Norway. These conditions gradually gave place to a more genial climate, which also induced a corresponding change in its flora. This apparently more temperate climate appears to have been succeeded by another change in the climatal conditions, this time of a less genial character, and not so favourable to the growth of the oaks, and to which they, in their turn, gradually yielded in point of luxuriance, and ultimately succumbed to the encroachment of the bogs and peat-mosses. To discuss at greater length the climatal changes which may have occurred since the great oaks and pines of our moss-covered forests flourished, would be a digression from the main object of this work. In geological and astronomical causes some scientists believe they have a sufficient explanation of the strange, and sometimes severe, oscillations that are known to have taken place in post-Tertiary times, so that the disappearance of the ancient forests from the country, and the subsequent increase of the peat bogs, may be looked upon as the effect rather than the cause of our altered climate. There can hardly be any doubt, however, that during prehistoric times, and towards the dawn of European history, North Britain was extensively covered with forests which were characterised by a luxuriance of growth which is not now attained in the same latitudes. Hence the statements made by Roman historians to the effect that the natives painted their bodies and roamed about in a semi-nude condition must not necessarily be stigmatised as fables. That the inhabitants themselves greatly contributed to the clearance of the woods and jungles, as they became practically acquainted with the advantages of systematic tillage of the ground, is also probable. But this change was not produced all at once, as it is proved by such numerous place-names as Woodlands, Woodend, Woodside, Linwood, Fulwood, Oakshaw-side, Oakshaw-head, Walkingshaw, Lainshaw, etc. etc., that the south-west of Scotland was well wooded