Section 290 Yards; Average Height, 125 Feet. (see Above Map of Moraine

between Speeton and Flamborough.)

Explanation.--4. Brownish boulder-clay, a band of pebbles; 4a, in places about seven feet from top. 3. Washed gravel, with thin sand-seams, well-bedded, pebbles chiefly erratics. 2. "Basement" boulder-clay, with many included patches of sand, gravel, and silt; 2a, at B, one of these 2b contain shells. 1b. Sand and silt, overlying and in places interbedded with 1. 1. Rubble of angular and subangular chalk-blocks and gravel, with occasional erratic, passes partly into chalky boulder-clay, 1a. x. White chalk, without flints, surface much shaken.]

"At Flamborough Head shelly drift attains an altitude of 400 feet, but half a mile from the coast the country is practically driftless even at lower levels. The Yorkshire Wolds were not submerged. On the western flanks of the wolds drift comes in at about 100 to 150 feet, and persists, probably, under the post-glacial warp, from which it again protrudes on the western side of the valley of the Ouse, and however the drift between there and the Pennine water-shed may be interpreted, it shows not a sign of marine origin; but, even granting that it did, we find that it does not reach within a thousand feet of the water-shed. When the water-shed is crossed, however, abundant glacial deposits are met with which are not to be differentiated from others at slightly lower levels which contain shells.

Explanation.--2. "Basement" boulder-clay. 2a. Pure compact blue and brown clay of aqueous origin, bedding contorted and nearly obliterated, but the mass is cut up by shearing planes. 2b. Irregular seam, and scattered streaks, of greenish-yellow sand with many marine shells. 2c. Patch of pale-yellow sand, different from 2b, without trace of fossils.]

"If we suppose that the line of our traverse crosses the Pennine Chain at Heald Moor, we shall find that on the eastern side no traces of drift occur above about 300 feet; while the very summit of the water-shed is occupied by boulder-clay, and thence downward the trace is practically continuous, and at about 1,000 feet and downward the drift contains marine shells. Across the great plain of Lancashire and Cheshire the 'marine' drift is fully developed--though it may be remarked in parentheses that it contains a shallow-water fauna, albeit ex hypothesi deposited, in part at least, in a depth of 200 fathoms of water--and to the Welsh border at Frondeg, where it again reaches a water-shed at an altitude of 1,450 feet; but at 100 yards to the westward of the summit all traces of subsidence disappear, and through the centre of Wales no sign is visible; then we emerge on the western slopes at Moel Tryfaen, and they assume their fullest dimensions, though only to finish abruptly on the hill-top, and put in no appearance in the lower grounds which extend from there to the sea.

"The conclusions pointed to by the evidence (and, as I have endeavoured to show, all the evidence which existed at the close of the Glacial period is there still) are, that a subsidence of the Yorkshire Wolds took place on the east, but not in the centre or west; that the Pennine Chain was submerged on the western side to a depth of 1,400 feet, and on the east to not more than 300 feet, even on opposite sides of the same individual hill; that all the lowlands between, say, Bacup and the Welsh border, were submerged, and that the hills near Frondeg partook of this movement, but only on their eastern sides; that the centre of Wales was exempt, but that the summit of Moel Tryfaen forms an isolated spot submerged, while the surrounding country escaped. These absurdities might be indefinitely multiplied, and they must follow unless it be admitted that the phenomena are the results of glacial ice, and that ice can move 'up-hill.'

"The south of England certainly has partaken of no movement of subsidence. A line drawn from Bristol to London will leave all the true glacial deposits to the northward, except a bed of very questionable boulder-clay at Watchet, and a peculiar deposit of clayey rubble which has been produced on the flanks of the Cornish hills probably, as the late S. V. Wood, Jr, suggested, by the slipping of material over a permanently frozen subsoil.

"For the remainder of the southern area the evidence is plain that there has been no considerable subsidence during glacial times. The presence over large areas of chalk country of the 'clay with flints'--a deposit produced by the gradual solution of the chalk and the accumulation in situ of its insoluble residue--is absolute demonstration that for immense periods of time the country has been exempt from any considerable aqueous action. The enormous accumulations of china clay upon the granite bosses of Cornwall and Devon tell the same tale. A few erratics have been found at low levels at various points on the southern coasts, usually not above the reach of the waves. These consist of rocks which may have been floated by shore-ice from the Channel Islands or the French coast.

"This imperfect survey of the evidence against the supposed submergence has been rendered the more difficult by the fact that it is not considered necessary to produce the evidence of marine shells in all cases. Indeed, it has been argued that post-Tertiary beds covering thousands of square miles might be absolutely destitute of shells without prejudice to the theory of their formation in the sea.

"But such a suggestion, one would think, could hardly come from anyone familiar with marine Tertiary deposits, or even with the appearance of modern sea-beaches. Admitting, however, for the purposes of argument, that the beaches along a great extent of coast might be devoid of shells, it cannot be argued that the deep waters were destitute of life; and hence the boulder-clays, if of marine origin, should contain a great abundance of shells and other remains, and, once entombed, it is beyond belief that they could all be removed from such a deposit in the short lapse of post-glacial time.

"Now, some of the boulder-clays--as, for example, those of Lancashire and Cheshire--are held to be of marine origin, and this is indeed a vital necessity to the submergence theory; for, if these are not marine deposits, neither are the other shelly deposits; but these boulder-clays are absolutely indistinguishable from those lying within the hill-centres, and, as it passes belief that such deposits could be of diverse origin and yet possess an identical structure and arrangement, then we should have a right to demand that these clays should have enclosed shells and should still contain them, but they do not.

"I may here mention that I am informed by Mr. W. Shone, F. G. S.--and he was good enough to permit me to quote the statement--that the boulder-clay of Cheshire and the shelly boulder-clay of Caithness are 'as like as two peas.' The importance of this comparison lies in the fact that, since Croll's classical description, all observers have agreed that it was the product of land-ice which moved in upon the land out of the Dornoch Firth. It was pointed out then, as since has been done for England, that it was only where the direction of ice-movement was from the seaward that any shells occur in the boulder-clay.

"The Dispersion of Erratics of Shap Granite.--So great a significance attaches to the peculiar distribution of this remarkable rock, that I may add a few details here which could not be conveniently introduced elsewhere.

"This granite occupies an area which lies just to the northward of the water-shed between the basins of the Lime and the Eden, and its extreme elevation is 1,656 feet. Boulders occur in large numbers as far to the northward as Cross Fells, while, as already described, they pass over Stainmoor and are dispersed in great numbers along the route taken by the great Stainmoor branch of the Solway Glacier. But a considerable number of the boulders also found their way to the southward, and a well-marked trail can be followed down into Morecambe Bay; and at Hest Bank, to the north of Lancaster, the boulder-clay contains many examples, together with the 'mica-trap' of the Kendal and Sedbergh dykes and other local rocks, but no shells or erratics from other sources than the country draining into Morecambe Bay. To the southward the ice which bore these rocks was deflected by the great Irish Sea Glacier, and, so far as present information enables me to state, the Shap granite blocks mark the course of the medial moraine between these two ice-streams. It has been found near Garstang, at Longridge, and at Whalley, this being the exact line of junction of the Irish Sea Glacier with the ice from Morecambe Bay and the Pennine Chain.

"It is a very remarkable and significant fact, that not a single authentic occurrence of the rock across the boundary indicated has yet been recorded."

Northern Europe.

On passing over the shallow German Sea from England to the Continent, the southern border of the Scandinavian ice-field is found south of the Zuyder Zee, between Utrecht and Arnhem--the moraine hills in the vicinity of Arnhem being quite marked, and a barren, sandy plain dotted with boulders and irregular moraine hills extending most of the way to the Zuyder Zee. From Arnhem the southern boundary of the great ice-field runs "eastward across the Rhine Valley, along the base of the Westphalian Hills, around the projecting promontory of the Hartz, and then southward through Saxony to the roots of the Erzgebirge. Passing next southeastward along the flanks of the Riesen and Sudeten chain, it sweeps across Poland into Russia, circling round by Kiev, and northward by Nijni-Novgorod towards the Urals." Thence the boundary passes northward to the Arctic Ocean, a little east of the White Sea.

The depth of this northern ice-sheet is proved to have been upwards of 1,400 feet where it met the Hartz Mountains, for it has deposited northern débris upon them to that height; while, as already shown, it must have been over 2,000 feet in the main valley of Switzerland. In Norway it is estimated that the ice was between 6,000 and 7,000 feet thick.

The amount of work done by the continental glaciers of Europe in the erosion, transportation, and deposition of rock and earthy material is immense. According to Helland, the average depth of the glacial deposits over North Germany and northwestern Russia is 150 German feet, i. e., about 135 English feet. As the deposition towards the margin of a glacier must be commensurate with its erosion near the centre of movement, this vast amount implies a still greater proportionate waste in the mountains of Scandinavia, where the area diminishes with every contraction of the circle. Two hundred and fifty feet is therefore not an extravagant calculation for the amount of glacial erosion in the Scandinavian Peninsula.

It is not difficult to see how the Scandinavian mountains were able to contribute so much soil to the plains of northern Germany and northwestern Russia. Previous to the Glacial period, a warm climate extended so far north as to permit the growth of semi-tropical vegetation in Spitsbergen, Greenland, and the northern shores of British America. Such a climate, with its abundant moisture and vegetation, afforded most favourable conditions for the superficial disintegration of the rocks. When, therefore, the cold of the Glacial period came on, the moving currents of ice would have a comparatively easy task in stripping the mantle of soil from the hills of Norway and Sweden, and transporting it towards the periphery of its movement. Of course, erosion in Scandinavia meant subglacial deposition beyond the Baltic. Doubtless, therefore, the plains of northern Germany, with their great depth of soil, are true glacial deposits, whose inequalities of surface have since been much obliterated, through the general influences of the lapse of time, and by the ceaseless activity of man.

An interesting series of moraines in the north of Germany, bordering the Baltic Sea, was discovered in 1888 by Professor Salisbury, of the United States Geological Survey. Its course lies through Schleswig-Holstein, Mecklenburg, Potsdam (about forty miles north of Berlin), thence swinging more to the north, and following nearly the line between Pomerania and West Prussia, crossing the Vistula about twenty miles south of Dantzic, thence easterly to the Spirding See, near the boundary of Poland.

Among the places where this moraine can be best seen are--"1. In Province Holstein, the region about (especially north of) Eutin; 2. Province Mecklenburg, north of Crivitz, and between Bütow and Kröpelin; 3. Province Brandenburg, south of Reckatel, between Strassen and Bärenbusch, south of Fürstenberg and north of Everswalde, and between Pyritz and Solden; 4. Province Posen, east of Locknitz, and at numerous points to the south, and especially about Falkenburg, and between Lompelburg and Bärwalde. This is one of the best localities. 5. Province West Preussen, east of Bütow; 6. Province Ost Preussen, between Horn and Widikin."

Comparing these with the moraines of America, Professor Salisbury remarks:

"In its composition from several members, in its variety of development, in its topographic relations, in its topography, in its constitution, in its associated deposits, and in its wide separation from the outermost drift limit, this morainic belt corresponds to the extensive morainic belt of America, which extends from Dakota to the Atlantic Ocean. That the one formation corresponds to the other does not admit of doubt. In all essential characteristics they are identical in character. What may be their relations in time remains to be determined."

The physical geography of Europe is so different from that of America, that there was a marked difference in the secondary or incidental effects of the Glacial period upon the two regions. In America the continental area over which the glaciers spread is comparatively simple in its outlines. East of the Rocky Mountains, as we have seen, the drainage of the Glacial period was, for a time, nearly all concentrated in the Mississippi basin, and the streams had a free course southward.

But in Europe there was no free drainage to the south, except over a small portion of the glaciated area in central Russia, about the head-waters of the Dnieper, the Don, and the Volga; though the Danube and the Rhône afforded free course for the waters of a portion of the great Alpine glaciers. But all the great rivers of northern Europe flow to the northward, and, with the exception of the Seine, they all for a time encountered the front of the continental ice-sheet. This circumstance makes it difficult to distinguish closely between the direct glacial deposits in Europe and those which are more or less modified by water-action. At first sight it would seem also somewhat hazardous to attempt to correlate with any portion of the Glacial period the deposition of the gravelly and loamy deposits in valleys, which, like those of the Seine and Somme, lie entirely outside of the glaciated area.

Upon close examination, however, the elements of doubt more and more disappear. The Glacial period was one of great precipitation, and it is natural to suppose that the area of excessive snow-fall extended considerably beyond the limit of the ice-front. During that period therefore, the rivers of central France must have been annually flooded to an extent far beyond anything which is known at the present time. Since these rivers flowed to the northward, at a period when, during the long and severe winters, the annual accumulation of ice near their mouths was excessive, ice-gorges of immense extent, such as now form about the mouths of the Siberian rivers, would regularly occur. We are not surprised, therefore, to find, even in these streams, abundant indications of the indirect influence of the great northern ice-sheet.

The indications referred to consist of high-level gravel terraces occasionally containing boulders, of from four to five tons weight, which have been transported for a considerable distance. The elevation of the terraces above the present flood-plains of the Seine and Somme reaches from 100 to 150 feet. We are not to suppose, however, that even in glacial times the floods of the river Seine could have filled its present valley to that height. The highest flood in this river known in historic times rose only to a height of twenty-nine feet. Mr. Prestwich estimates that, without taking into consideration the more rapid discharge, a flood of sixty times this magnitude would be required to fill the present valley to the level of the ancient gravels, while at Amiens the shape of the valley of the Somme is such that five hundred times the mean average of the stream would be required to reach the high-level gravels. The conclusion, therefore, is that the troughs of these streams have been largely formed by erosion since the deposition of the high-level gravels.

Connected with these terrace gravels in northern France is a loamy deposit, corresponding to the loess in other parts of Europe, and to a similar deposit to which we have referred in describing the southwestern part of the glaciated area in North America. In northern France this fine silt overlies the high-level gravel deposits, and, as Mr. Prestwich has pretty clearly shown, was deposited contemporaneously with them during the early inundations and before the stream had eroded its channel to its present level.

The distribution of loess in Europe was doubtless connected with the peculiar glacial conditions of the continent. Its typical development is in the valley of the Rhine, where it is described by Professor James Geikie "as a yellow or pale greyish-brown, fine-grained, and more or less homogeneous, consistent, non-plastic loam, consisting of an intimate admixture of clay and carbonate of lime. It is frequently minutely perforated by long, vertical, root-like tubes which are lined with carbonate of lime--a structure which imparts to the loess a strong tendency to cleave or divide in vertical planes. Thus it usually presents upright bluffs or cliffs upon the margins of streams and rivers which intersect it. Very often it contains concretions or nodules of irregular form.... Land-shells and the remains of land animals are the most common fossils of the loess, but occasionally fresh-water shells and the bones of fresh-water fish occur."

"From the margins of the modern alluvial flats which form the bottoms of the valleys it rises to a height of 200 or 300 feet above the streams--sweeping up the slopes of the valleys, and imparting a rich productiveness to many districts which would otherwise be comparatively unfruitful. From the Rhienthal itself it extends into all the tributary valleys--those of the Neckar, the Main, the Lahn, the Moselle, and the Meuse, being more or less abundantly charged with it. It spreads, in short, like a great winding-sheet over the country--lying thickly in the valleys and dying off upon the higher slopes and plateaux. Wide and deep accumulations appear likewise in the Rhône Valley, as also in several other river-valleys of France, as in those of the Seine, the Saône, and the Garonne, and the same is the case with many of the valleys of middle Germany, such as those of the Fulda, the Werra, the Weser, and the upper reaches of the great basin of the Elbe. It must not be supposed that the loess is restricted to valleys and depressions in the surface of the ground.

"It is true that it attains in these its greatest thickness, but extensive accumulations may often be followed far into the intermediate hilly districts and over the neighbouring plateaux. Thus the Odenwald, the Taunus, the Vogelgebirge, and other upland tracts, are cloaked with loess up to a considerable height. Crossing into the drainage system of the Danube, we find that this large river and many of its tributaries flow through vast tracts of loess. Lower Bavaria is thickly coated with it, and it attains a great development in Bohemia, Upper and Lower Austria, and Moravia--in the latter country rising to an elevation of 1,300 feet. It is equally abundant in Hungary, Galicia, Bukowina, and Transylvania. From the Danubian flat lands and the low grounds of Galicia it stretches into the valleys of the Carpathians, up to heights of 800 and 2,000 feet. In some cases it goes even higher--namely, to 3,000 feet, according to Zeuschner, and to 4,000 or 5,000 feet, according to Korzistka. These last great elevations, it will be understood, are in the upper valleys of the northern Carpathians. In Roumania loess is likewise plentiful, but it has not been observed south of the Balkans. East of the Carpathians--that is to say, in the regions watered by the Dniester, the Dnieper, and the Don--loess appears also to be wanting, and to be represented by those great steppe-deposits which are known as Tchernozen, or black earth."

The shells found in the loess indicate both a colder and a wetter climate during its deposition than that which now exists. The relics of land animals are infrequently found in the deposit, yet they do occur, but mostly in fragmentary condition--the principal animals represented being the mammoth, the rhinoceros, the reindeer, and the horse; which is about the same variety as is found in the gravel deposits of the Glacial period, both in western Europe and in America.

A species of loess--differing, however, somewhat in color from that on the Rhine--covers the plains of northeastern France up to an elevation of 700 feet above the the sea, where, as we have already said, it overlies the high-level gravels of the Seine and the Somme. Above this height the superficial soil in France is evidently merely the decomposed upper surface of the native rock.

The probable explanation of all these deposits, included under the term "loess," is the same as that already given by Prestwich of the loamy deposits of northern France. But in case of rivers, which, like the Rhine, encountered the ice-front in their northward flow, a flooded condition favouring the accumulation of loess was doubtless promoted by the continental ice-barrier. In the case of the Danube and the Rhône, however, where there was a free outlet away from the glaciated region, the loess in the upper part of the valleys must have accumulated in connection with glacial floods quite similar to those which we have described as spreading over the imperfectly formed water-courses of the Mississippi basin during the close of the Ice age. That the typical loess is of glacial origin is pretty certainly shown, both by its distribution in front of glaciers and by its evident mechanical origin when studied under the microscope. It is, in short, the fine sediment which gives the milky whiteness to glacial rivers.

In central Russia there is a considerable area in which the glacial conditions were, in one respect, similar to those in the northern part of the Mississippi Valley in the United States. In both regions the continental ice-sheet surmounted the river partings, and spread over the upper portion of an extensive plain whose drainage was to the south. The Dnieper, the Don, and the western branch of the Volga, like the Ohio and the Mississippi, have their head-waters in the glaciated region. In some other respects, also, there is a resemblance between the plains bordering the glaciated region in central Russia and those which in America border it in the Mississippi Valley. Mr. James Geikie is of the opinion that the extensive belt of black earth adjoining the glaciated area in Russia, and constituting the most productive agricultural portion of the country, derives its fertility, as does much of the Mississippi Valley, from the blanket of glacial silt spread pretty evenly over it. Thus it would appear that in Europe, as in America, the ice of the Glacial period was a most beneficent agent, preparing the face of the earth for the permanent occupation of man. On both continents the seat of empire is in the area once occupied by the advance of the great ice-movements of that desolate epoch.

Asia.

East of the Urals, in northern Asia, there is no evidence of moving ice upon the land during the Glacial period; but at Yakutsk, in latitude 62° north, the soil is frozen at the present time to an unknown depth, and many of the Siberian rivers, as they approach and empty into the Arctic Sea, flow between cliffs of perpetual ice or frozen ground. The changes that came over this region during the Glacial period are impressively indicated by the animal remains which have been preserved in these motionless icy cliffs. In the early part of the period herds of mammoth and woolly rhinoceros roamed over the plains of Siberia, and waged an unequal warfare with the slowly converging and destructive forces. The heads and tusks of these animals were so abundant in Siberia that they long supplied all Russia with ivory, besides contributing no small amount for export to other countries. "In 1872 and 1873 as many as 2,770 mammoth-tusks, weighing from 140 to 160 pounds each, were entered at the London clocks." So perfectly have the carcasses of these extinct animals been preserved in the frozen soil of northern Siberia that when, after the lapse of thousands of years, floods have washed them out from the frozen cliffs, dogs and wolves and bears have fed upon their flesh with avidity. In some instances even "portions of the food of these animals were found in the cavities of the teeth. Microscopic examination showed that they fed upon the leaves and shoots of the coniferous trees which then clothed the plains of Siberia." A skeleton and parts of the skin, and some of the softer portions of the body of a mammoth, discovered in 1799 in the frozen cliff near the mouth of the Lena, was carried to St. Petersburg in 1806, from which it was ascertained that this huge animal was "covered with alight-coloured, curly, very thick-set hair one to two inches in length, interspersed with darker-colored hair and bristles from four to eighteen inches long."

In the valleys of Sikkim and eastern Nepaul, in northern India, glaciers formerly extended 6,000 feet lower than now, or to about the 5,000-foot level, and in the western Himalayas to a still lower level. The higher ranges of mountains in other portions of Asia also show many signs of former glaciation. This is specially true of the Caucasus, where the ancient glaciers were of vast extent. According, also, to Sir Joseph Hooker, the cedars of Lebanon flourish upon an ancient moraine. Of the glacial phenomena in other portions of Asia little is known.

Africa.

Northern and even central Africa must likewise come in for their share of attention. The Atlas Mountains, rising to a height of 13,000 feet, though supporting none at the present time, formerly sustained glaciers of considerable size. Moraines are found in several places as low as the 4,000-foot level, and one at an altitude of 4,000 feet is from 800 to 900 feet high, and completely crosses and dams up the ravine down which the glacier formerly came.

Some have supposed that there are indubitable evidences of former glaciation in the mountain-ranges of southwestern Africa between latitude 30° and 33°, but the evidence is not as unequivocal as we could wish, and we will not pause upon it.

The mountains of Australia, also, some of which rise to a height of more than 7,000 feet, are supposed to have been once covered with glacial ice down to the level of 5,800 feet, but the evidence is at present too scanty to build upon. But in New Zealand the glaciers now clustering about the peaks in the middle of the South Island, culminating in Mount Cook, are but diminutive representatives of their predecessors. This is indicated by extensive moraines in the lower part of the valleys and by the existence of numerous lakes, attributable, like so many in Europe and North America, to the irregular deposition of morainic material by the ancient ice-sheet.