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preserved in its bed, we learn something of the atmospheric and physical conditions of the period in which the excavation of the valley proceeded. The vast accumulations of gravel and sediment that now stretch for miles on either side of the river, tell us of the wider and more vigorous stream from which they were deposited. They afford us, too, a vision of the Thames in the remotest ages of England's history. We see it as a terrible and devastating creature in the landscape, and not as now the captive and servant of man.

The Thames of to-day: an Artificial River reaching the Sea by an Aqueduct.

We shall the more easily read with the geologist some of these wonderful memoirs of the ancient Thames, if we realise to ourselves how artificial a river is the Thames of to-day. A steam-boat ride from London to Kew, or from London to Erith, suffices for our purpose. It enables us to see even in these modern days how slight are the barriers which withhold from our view one of the wildest aspects which the Thames Valley of primeval England presented. As we traverse the river we observe with a new significance the embankments which imprison the waters, and conduct them down to the sea. The dense and spreading forests and the gigantic mammalia of the early Thames-country are indeed missing, but how soon the wide waste of waters which once shared the landscape with them would return to its old familiar bed were the river released for a day from the restraints which man has imposed! It is these old embankments of the Thames that daily save the prosperous and populous valley from the wasteful spread of the river and the incursions of the sea- —from again becoming the wide enormous marsh or broad estuary. These early embankments of the Thames take us back to the latest stage in the history of the natural river, whose existence they may be said to have terminated. The magnitude and extent of these stupendous memorials of early civilisation in England is but little known or appreciated. Yet it is these which have converted the Thames into an aqueduct throughout the whole length of its tidal course. They extend from near Richmond to the mouth of the river. They stretch along the broad reaches and

follow the sinuosities of the river, winding up creeks and tributary streams, around islands, and about marshes. The entire distance they thus traverse is not less than 300 miles.* Thus vastly do these

function and in the

old earthwork embankments surpass in their prowess of their unknown builders the ornamental river wall which is the newest boast of London to-day. Were there no embankment at Kew the Thames must fail to reach London as a river.

Here

What the country below London would be without its river embankments may easily be seen at Dagenham. Dagenham is celebrated in the annals of the Thames engineers. It is here that the skill and persistence of man in conflict with nature have been tasked to the utmost in the endeavour to keep the river a captive. at Dagenham (on the north bank of the river, and a little to the south of the village), we may stand on an embankment which rises to a height of forty feet above the low-water level of the river, and prevents it from entirely changing its course. We might multiply instances to show how largely the Thames of to-day is the gift of civilisation rather than of Nature-the creature as well as the servant of man.

The Thames of the Mammoth Period.

But the old embankments of the Thames can take us no further in our upward route than the beginnings of civilisation in Britain. It is here, when we are almost in sight of the natural and primitive river, that we must cast ourselves adrift from the so-called historical period, and embark on the expanse of the wide geological ages. But the prospect, according to the geologist, need not dismay us. In comparing the chronicles of Nature with the chronicles of man, it is not seldom that terra firma is found outside and beyond the so-called historical periods rather than within it. In the history of rivers, seas, and continents, we arrive, as it were, at

*Lives of the Engineers, I., v.-" A good idea of the formidable character of the embankments extending along the Thames may be obtained by a visit to Dagenham. Here the banks are from seventeen to twenty five feet

high, and from twenty five to thirty feet at the base."-Ibid. Mr. Smiles gives two remarkable views of the river at high water at Dagenham, in which the character of the Thames as an aqueduct is well shown.

visible landmarks, signalising to us definite eras of geographical change, and indicating the processes and events which give sequence and history to phenomena.

Sir Charles Lyell, following an eminent geologist of the last generation,* refers us to an era in the history of the Thames when it was probably a tributary of the Rhine. "For England was then united to the Continent, and what is now the German Ocean was then land." Such was the current tradition in England even

before the spread of geological discovery.

The Gaul, 'tis said in antique story,

Saw Britain link'd to his now adverse strand,

No sea between, no cliff sublime and hoary,

He walked with unwet feet through all our land.

This former continuity of land which is now separated by the Straits of Dover, the existence of which would be an eventful phase in the history of the Thames, is credible upon evidence which is both stratigraphical and biological, and seems to make it certain, even to the ordinary observer, that the Thames has had its continental as well as its insular period of existence. The separation of England from the Continent is geologically recent. We still find on the shores of Kent the beds of old rivers which obviously were once continuous farther eastward, but which now end off suddenly at the top of the scarp, at a height far above the sea level.

The geographical conditions of primeval England which rendered it possible for the Thames to be a tributary of the Rhine are necessary in the eyes of the biologist to account for the presence in our land of huge, strange, and now extinct species of the brute creation, the remains of which are found to-day in the river-valley about London. These gigantic creatures, the mammoth and its fellowelephants of other species, the rhinoceros, the hippopotamus, and others, contribute a romantic yet sober chapter to the natural history of the Thames. Monstrous fleece-clad quadrupeds grazed and browsed on the banks of the Thames and drank its waters. The Siberian mammoth, with long black hair and an undercoat of reddish wool; elephants of other species, and two-horned

*Quarterly Geological Journal, vol. ix.

Antiquity of Man, chap. ix.

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rhinoceri, all clad in fleeces as if to protect them from the rigours of an Arctic climate, are found making their home in the basin of the Thames, where the forests afforded them suitable food.* Here, as in adjacent parts of England, they shared the land with the reindeer and the bear. Here around London roamed

The wild herds that own no master's stall.

The lion, the tiger and other carnivora followed in the track of the vegetable-feeding animals. The victims sometimes of sudden floods, they were engulfed in the deep waters, and in time embedded in the mud of the stream. The remains of these huge pre-Adamites and fierce carnivora thus survived great changes in the physical condition of the country in which they lived, and reveal to man in after ages the zoology and geography of their period.

A Visit to the Graves of the Thames Mammoths.

We may easily see for ourselves what kind of chronicles they are which tell of the continental ages of our country's history, when

Mighty pre-Adamites walked the earth

Of which ours is the wreck

when herds of mammoths and rhinoceri found a natural home in England and roamed at will from the banks of the Thames to the Seine. For this purpose let us make a visit to one of the graves of these old zoological races. We may choose the Erith sand-pits on the south shore of the river, or the Ilford and Gray's brick-fields on the north as the place of our visit. In either case we shall find that the river has been its own historian, and the historian of the surrounding country, under geographical circumstances greatly differing from those of to-day. The Ilford brick-fields should be preferred, as they are celebrated for their mammalian remains of the early Thames-country. The pit which has the greatest repute for containing bones of the mammoth and rhinoceros is about a quarter of a mile beyond Ilford, on the left hand side of the high road from London to Ipswich. A visit early in the year is the most likely to

*See British Fossil Mammals: Prof. OWEN.

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reward us for our trouble. In the early spring the pits are open for the purpose of removing the clay for the uses of the brick-field. As the earth is removed and the perpendicular sections are gradually exposed, we may look hopefully for some indications of animal remains. The workmen at length call our attention to a spot where the earth is denser, richer in colour, and more unctuous than that which surrounds it. But unless some skilled fossil-seeker is attached to the party, the embedded mammoth or hippopotamus may even now vanish before our eyes. The bones must be uncovered with the greatest ingenuity and care, if they are to be properly extricated from their earthy matrix and preserved in a permanent form. These mortal remains are generally as friable as the soil itself, and the evaporation which sets in as soon as they are exposed to the air causes them in many instances rapidly to crumble away.

But invention, in fossil-seeking as in other pursuits, is born of necessity, and we have seen at Ilford, as well as at other fossil localities, an ingenious method of extricating and preserving the imperilled and vanishing prize. With moist clay and plaster of Paris the upper side of the bone or skeleton is first coated. With skill, patience, and careful under-cutting, the prize is at length turned over, and its under-side similarly treated. After entire excavation the bones are immersed in liquid size, of which they are allowed to absorb sufficient to keep them from fracture and fit them for removal. The hardening process is completed by giving them a bath of hot sand, in which they remain for a day or two, By a treatment of which these are the chief processes, not a few valuable remains of the Thames pachyderms discovered at Ilford and Erith, which would otherwise have perished in extrication, or within a short time of exposure, have been preserved for the national museum or private collection.*

These remains of gigantic and now extinct species of quadrupeds

* A full description of this process is given in The Field, March 6, 1869, by J. H. L. Sir Antonio Brady, a great collector of the pre-historic remains of the Thames Valley,

intends to deposit his magnificent series of mammoth and other fossil specimens in the new East London Museum.-Ibid.

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