The Antiquity of Man Part 21

The insects, so far as they are known, including several species of Donacia, are, like the plants and freshwater sh.e.l.ls, of living species.

It may be remarked, however, that the Scotch fir has been confined in historical times to the northern parts of the British Isles, and the spruce fir is nowhere indigenous in Great Britain. The other plants are such as might now be found in Norfolk, and many of them indicate fenny or marshy ground.*

(* Mr. King discovered in 1863, in the forest bed, several rhizomes of the large British fern Osmunda regalis, of such dimensions as they are known to attain in marshy places.

They are distinguishable from those of other British ferns by the peculiar arrangement of the vessels, as seen under the microscope in a cross section.)

When we consider the familiar aspect of the flora, the accompanying mammalia are certainly most extraordinary. There are no less than three elephants, a rhinoceros and hippopotamus, a large extinct beaver, and several large estuarine and marine mammalia, such as the walrus, the narwhal, and the whale.

The following is a list of some of the species of which the bones have been collected by Messrs. Gunn and King.

Those marked (asterisk) have been recorded by Professor Owen in his British Fossil Mammalia. Those marked (dagger) have been recognised by the same authority in the cabinets of Messrs. Gunn and King, or in the Norwich Museum; the other three are given on the authority of Dr.

Falconer.

MAMMALIA OF THE FOREST AND LIGNITE BEDS BELOW THE GLACIAL DRIFT OF THE NORFOLK CLIFFS.

Elephas meridionalis.

(asterisk) Elephas primigenius.

Elephas antiquus.

Rhinoceros etruscus.

(asterisk) Hippopotamus (major?).

(asterisk) Sus scrofa.

(asterisk) Equus (fossilis?).

(asterisk) Ursus (sp.?).

(dagger) Canis lupus.

(dagger) Bison priscus.

(dagger) Megaceros hibernicus.

(asterisk) Cervus capreolus.

(dagger) Cervus tarandus.

(dagger) Cervus Sedgwickii.

(asterisk) Arvicola amphibia.

(asterisk) Castor (Trogontherium) Cuvieri.

(asterisk) Castor europaeus.

(asterisk) Palaeospalax magnus.

(dagger) Trichecus rosmarus, Walrus.

(dagger) Monodon monoceros, Narwhal.

(dagger) Balaenoptera.

Mr. Gunn informs me that the vertebrae of two distinct whales were found in the fluvio-marine beds at Bacton, and that one of them, shown to Professor Owen, is said by him to imply that the animal was 60 feet long. A narwhal's tusk was discovered by Mr. King near Cromer, and the remains of a walrus. No less than three species of elephant, as determined by Dr. Falconer, have been obtained from the strata 3 and 3 prime, of which, according to Mr. King, E. meridionalis is the most common, the mammoth next in abundance, and the third, E. antiquus, comparatively rare.

The freshwater sh.e.l.ls accompanying the fossil quadrupeds, above enumerated, are such as now inhabit rivers and ponds in England; but among them, as at Runton, between the "forest bed" and the glacial deposits, a remarkable variety of the Cyclas amnica occurs (Figure 28), identical with that which accompanies the Elephas antiquus at Ilford and Grays in the valley of the Thames.

All the freshwater sh.e.l.ls of the beds intervening between the Forest-bed Number 3, and the glacial formation 4, Figure 27, are of Recent species. As to the small number of marine sh.e.l.ls occurring in the same fluvio-marine series, I have seen none which belonged to extinct species, although one or two have been cited by authors. I am in doubt, therefore, whether to cla.s.s the forest bed and overlying strata as Pleistocene, or to consider them as beds of pa.s.sage between the Pliocene and Pleistocene periods. The fluvio-marine series usually terminates upwards in finely laminated sands and clays without fossils, on which reposes the boulder clay.

[Ill.u.s.tration: Figure 28. Cyclas]

(FIGURE 28. Cyclas (Pisidium) amnica var.?

The two middle figures are of the natural size.)

This formation, Number 4, is of very varying thickness. Its glacial character is shown, not only by the absence of stratification, and the great size and angularity of some of the included blocks of distant origin, but also by the polished and scratched surfaces of such of them as are hard enough to retain any markings.

Near Cromer, blocks of granite from 6 to 8 feet in diameter have been met with, and smaller ones of syenite, porphyry, and trap, besides the wreck of the London Clay, Chalk, Oolite, and Lias, mixed with more ancient fossiliferous rocks. Erratics of Scandinavian origin occur chiefly in the lower portions of the till. I came to the conclusion in 1834, that they had really come from Norway and Sweden, after having in that year traced the course of a continuous stream of such blocks from those countries to Denmark, and across the Elbe, through Westphalia, to the borders of Holland. It is not surprising that they should then reappear on our eastern coast between the Tweed and the Thames, regions not half so remote from parts of Norway as are many Russian erratics from the sources whence they came. [22]

[Ill.u.s.tration: Figure 29. Cliff]

(FIGURE 29. CLIFF 50 FEET HIGH BETWEEN BACTON GAP AND MUNDESLEY.

Section through Gravel (top), Sand, Loam and Till (bottom).)

According to the observations of the Reverend J. Gunn and the late Mr.

Trimmer, the glacial drift in the cliffs at Lowestoft consists of two divisions, the lower of which abounds in the Scandinavian blocks, supposed to have come from the north-east; while the upper, probably brought by a current from the north-west, contains chiefly fragments of Oolitic rocks, more rolled than those of the lower deposit. The united thickness of the two divisions, without reckoning some interposed laminated beds, is 80 feet, but it probably exceeds 100 feet near Happisburgh.*

(* "Quarterly Journal of the Geological Society" volume 7 1851 page 21.)

Although these subdivisions of the drift may be only of local importance, they help to show the changes of currents and other conditions, and the great lapse of time which the acc.u.mulation of so varied a series of deposits must have required.

The lowest part of the glacial till, resting on the laminated clays before mentioned, is very even and regular, while its upper surface is remarkable for the unevenness of its outline, owing partly, in all likelihood, to denudation, but still more to other causes presently to be discussed.

The overlying strata of sand and gravel, Number 5, Figure 27, often display a most singular derangement in their stratification, which in many places seems to have a very intimate relation to the irregularities of outline in the subjacent till. There are some cases, however, where the upper strata are much bent, while the lower beds of the same series have continued horizontal. Thus the annexed section (Figure 29) represents a cliff about 50 feet high, at the bottom of which is till, or unstratified clay, containing boulders, having an even horizontal surface, on which repose conformably beds of laminated clay and sand about 5 feet thick, which, in their turn, are succeeded by vertical, bent, and contorted layers of sand and loam 20 feet thick, the whole being covered by flint gravel. The curves of the variously coloured beds of loose sand, loam, and pebbles, are so complicated that not only may we sometimes find portions of them which maintain their verticality to a height of 10 or 15 feet, but they have also been folded upon themselves in such a manner that continuous layers might be thrice pierced in one perpendicular boring.

[Ill.u.s.tration: Figures 30 and 31. Strata]

(FIGURE 30. FOLDING OF THE STRATA BETWEEN EAST AND WEST RUNTON.)

(FIGURE 31. SECTION OF CONCENTRIC BEDS WEST OF CROMER.

1. Blue clay.

2. White sand.

3. Yellow Sand.

4. Striped loam and clay.

5. Laminated blue clay.)

At some points there is an apparent folding of the beds round a central nucleus, as at a, Figure 30, where the strata seem bent round a small ma.s.s of Chalk, or, as in Figure 31, where the blue clay Number 1 is in the centre; and where the other strata 2, 3, 4, 5 are coiled round it; the entire ma.s.s being 20 feet in perpendicular height. This appearance of concentric arrangement around a nucleus is, nevertheless, delusive, being produced by the intersection of beds bent into a convex shape; and that which seems the nucleus being, in fact, the innermost bed of the series, which has become partially visible by the removal of the protuberant portions of the outer layers.

To the north of Cromer are other fine ill.u.s.trations of contorted drift reposing on a floor of Chalk horizontally stratified and having a level surface. These phenomena, in themselves sufficiently difficult of explanation, are rendered still more anomalous by the occasional enclosure in the drift of huge fragments of Chalk many yards in diameter. One striking instance occurs west of Sheringham, where an enormous pinnacle of Chalk, between 70 and 80 feet in height, is flanked on both sides by vertical layers of loam, clay, and gravel (Figure 32).

[Ill.u.s.tration: Figure 32. Pinnacle of Chalk]

(FIGURE 32. INCLUDED PINNACLE OF CHALK AT OLD HYTHE POINT, WEST OF SHERINGHAM.

d. Chalk with regular layers of flints.

c. Layer called "the pan," of Chalk, flints, and marine sh.e.l.ls of Recent species, cemented by oxide of iron.)

This chalky fragment is only one of many detached ma.s.ses which have been included in the drift, and forced along with it into their present position. The level surface of the Chalk in situ (d) may be traced for miles along the coast, where it has escaped the violent movements to which the inc.u.mbent drift has been exposed.*

(* For a full account of the drift of East Norfolk, see a paper by the author, "Philosophical Magazine" Number 104 May 1840.)

We are called upon, then, to explain how any force can have been exerted against the upper ma.s.ses, so as to produce movements in which the subjacent strata have not partic.i.p.ated. It may be answered that, if we conceive the till and its boulders to have been drifted to their present place by ice, the lateral pressure may have been supplied by the stranding of ice-islands. We learn, from the observations of Messrs.

Dease and Simpson in the polar regions, that such islands, when they run aground, push before them large mounds of shingle and sand. It is therefore probable that they often cause great alterations in the arrangement of pliant and incoherent strata forming the upper part of shoals or submerged banks, the inferior portions of the same remaining unmoved. Or many of the complicated curvatures of these layers of loose sand and gravel may have been due to another cause, the melting on the spot of ice-bergs and coast ice in which successive deposits of pebbles, sand, ice, snow, and mud, together with huge ma.s.ses of rock fallen from cliffs, may have become interstratified. Ice-islands so const.i.tuted often capsize when afloat, and gravel once horizontal may have a.s.sumed, before the a.s.sociated ice was melted, an inclined or vertical position. The packing of ice forced up on a coast may lead to a similar derangement in a frozen conglomerate of sand or shingle, and, as Mr.

Trimmer has suggested,* alternate layers of earthy matter may have sunk down slowly during the liquefaction of the intercalated ice so as to a.s.sume the most fantastic and anomalous positions, while the strata below, and those afterwards thrown down above, may be perfectly horizontal (see above).