37G

THE FOSSILIFEROUS DEPOSITS

of England ; and tlie group, however fragmentary and incom-plete, must be regarded as possessing a certain interest of itsown, in its character as a portion of the fossil records of acountry whose later geologic history, like her civil one bothlate and early, is meagre in its authentic materials, and, inconsequence, unsatisfactory in its details.

With but one baiting place,—that furnished by his Gracethe Duke of Argyle’s discovery of Miocene leaf-beds in theIsland of Mull, —we have to stride, in Scotland , whollyacross the Tertiary divisions, and find our first footing on thedeposits of the Pleistocene . I have not yet seen the leaf-bedsrepresented in any collection, save the great British one inJermyn Street. They must, however, be regarded as pos-sessing peculiarly a Scotch interest, not merely from theglimpse which they yield us of those old dicotyledonous forestsof our country which succeeded, after the lapse of unreckon-ed ages, the coniferous forests of the Oolite, but also from thecircumstance of their irrefragably demonstrating that, up tilla comparatively late period, Scotland had its great outburstsof Trap. A thick bed of rudely columnar basalt overliesthe most modern of these beds; and deposits of trap tuff,in which his Grace detected rolled chalk flints, overlie theolder ones } thus showing, that long after the times of theChalk, and when trees allied to the yew, the plane, and thebuckthorn, grew in our forests, those deluges of molten mat-ter from the abyss which had obtained throughout the earliergeologic ages, had not yet ceased, but were, on the contrary,potent enough to overspread wide areas to the depth of fromtwenty to forty feet. From these times of fire we at oncepass, in this northern part of the island, to a period of ice,—to the ages represented by grooved and polished surfaces, tra-velled rocks, boreal shells, and the boulder clay. Thoughgeologically the period was one, it yields, I am disposed tothink, evidence of three distill successive stages.