CHAPTER XIV. THE STORY OF A BOULDER. "As a huge stone is sometimes seen to lie, By what means it could thither come, and whence- WORDSWORTH. EW of my fellow story-tellers can boast of adventures equal to mine. My life has been a restless one, and to see me quietly reposing in some bed of clay, the non-geologist would little suspect what strange romances I could tell him. I will do my best to recount them. Not many years ago this would have been totally impossible. At that time geology was chiefly made up of guesses, many of which, however, proved to be shrewdly true. The great sheets of sand, gravel, and clay which extend, more or less, over the northern, midland, and eastern counties of England-as well as over the Continent and in the United States of America, were supposed to have been the débris left by Noah's Flood, and were therefore called "Diluvium." But facts (stubborn things!) have accumulated in such numbers that it is now totally impossible to hold such an idea-much as many people may wish it. It is seen that the period of time when such beds were formed was as peculiar as those of other formations, and that the physical circumstances, if not the peculiar life-forms, marked it off distinctly from the rest. Hence the name now given to it of "Northern Drift," or that other of the "Glacial period," which latter I hold to be the most appropriate. The chief interest of the "Glacial epoch" is the way with which its facts connect older tertiary life-forms and geography with existing species and circumstances. The geologist is able to perceive there was no break, such was originally supposed, but that the present epoch is intimately related to all that have gone before, and is, in fact, a continuation of many of their circumstances. It therefore links the present with the past, in a way for which knowledge-seekers cannot be too thankful. Who would imagine the scattered, disunited beds of clay, or gravel, or sand, could have been so fruitful in geological and even general interest? Some of my companions may boast of an origin. quite the opposite to my own. Theirs deals with intense heat, mine with almost as extreme cold. Of course I am speaking of my present existence as a "boulder; " for before I entered that state I formed an insignificant part of a great and continuous rocky stratum. What this rock was composed of, matters little or nothing, for we "Glacial Boulders" have no such clannish feeling as other geological storytellers. We are composed of all kinds—and the bed of clay in which we have been deposited may be regarded as a sort of lithological Parliament, in which the representatives of every formation are assembled. But allow me, if you please, rapidly to sketch the outlines of the events which transpired before I was ruthlessly wrenched from my original rocky home, and transposed into a boulder. As many of my hearers are aware, the earlier part of the Tertiary period was, in England and elsewhere, marked by an almost tropical climate. During the Eocene epoch, the seas of our latitude were inhabited by shells and fish of tropical types. The dry land was clothed with tree-ferns, palms, &c., and these gorgeous forests were frequented by huge serpents, strange-looking, tapir-like quadrupeds, and monkeys. The rivers, also, had their alligators and crocodiles. In short, all the types of land, freshwater, and marine fauna and flora, which now distinguish equatorial regions, existed in England. The rocks of this period are full of proofs of the truth of what I say. Then gradually succeeded the Miocene epoch, during which the climature was less torrid. Even then, the great Arctic ice-cap had not been formed at the pole; for we have abundant evidence that countries situated far north, such as Greenland and Spitzbergen, were covered with vegetable forms nearly allied to those now living in South Carolina, Japan, the Cape of Good Hope, and Australia. Then succeeded the Pliocene age, whose climate is abundantly indicated by its fine "Crags," as the beds of shells are termed. The oldest of these is called the "Coralline," and there may be found in it no fewer than twenty-seven species of shells, nearly allied to or identical with those now existing in southern latitudes. The "Red Crag" comes next in age, and this tells you by similar evidence that the climate was gradually getting colder, for the number of southern shells had dwindled to thirteen, whilst there has appeared in English latitudes species allied to those now living in northern seas. Finally, the third, or "Norwich Crag," supplements the teachings of its relatives by its total absence of southern shells, and its much greater proportion of Arctic species. Another bed of Crag, situated some height above this, still further corroborates the remarkable fact I have been narrating, for its greater abundance of northern forms is as remarkable as that of the older Norwich Crag over the red. About the same age as the latter bed is a phenomenon, known as the "Forest bed," which crops out from beneath the steep cliffs along the Norfolk and Suffolk coasts. It is the site of an old forest, now forming the floor of the German Ocean, and the imbedded stools of trees, as well as those of land and fresh-water plants, indicate a temperate mildness of climate, similar to that now marking the British islands—or, if anything, a trifle colder, as the pre R sence of the Scotch fir and Norway spruce pine clearly shows. My hearers cannot but be struck with the gradual refrigeration of climate, from a tropical or subtropical condition, to a temperate one. Meantime, the slow but sure change from warmer to colder physical circumstances clearly prophesied that the next period would probably be marked by the same law. Such proved to be the case. The change of climate indicated by the several periods I have mentioned, culminated in that "Glacial period" during which my birth as a boulder took place. After the epoch of the "Crags," a gradual subsidence of England, at least as far south as what is now the Thames, slowly took place. Little by little the whole country sunk beneath the sea, in which, with increasing depth, there came increased Arctic cold. The greater part of Scotland-certainly the whole of the Highlands-was covered with land-ice, or sheets of accumulated snow, frozen into ice. The snow-line-which in England is now some thousands of feet above the ocean-level-then was gradually lowered by the greater cold until it was met with as low as it could possibly creep. The hills of North Wales, Cumberland, Lancashire, and other places also had their ice-sheets and glaciers. To what thickness this great ice-mass accumulated, or from what cause, I can form no idea; but if it was anything like what now takes place in Greenland—and I have every reason for asserting that England at the time of which |