The Geological Story of the Isle of Wight Part 7

When the Solent and Southampton Water were wooded valleys with rivers flowing down the middle, the Isle of Wight rivers were tributaries to the Solent river, and the forest, as might be expected, extended up their valleys, and covered the low ground of the Island. Under the alluvial flats are remains of buried forests. In digging a well at Sandford in 1906 large trunks of hard oak were found blocking the sinking of the well. When the land sank the sea flowed up the river valleys, converting them into strait and estuary, and largely filling up the channels with the silt, which now covers the peat. In the silt of Newtown river are found bones of _Bos primigenius_, which was found with the Neolithic remains in the peat of Southampton docks.

The remains of Neolithic man are not only found in submerged forests, but over the present surface of the land, or buried in recent deposits. He has left us the tombs of his chiefs, known as long barrows--great mounds of earth covering a row of chambers made of flat stones, such as the mounds of New Grange in Ireland, and the cromlechs or dolmens still standing in Wales and Cornwall. These consist of a large flat or curved stone--it may be 14 feet in length,--supported on three or four others. Originally a great mound of earth or stones was piled on top. These have generally been removed since by the hand of later man. The stones have been taken for road metal, the earth to lay on the land. The great cromlech at Lanyon in Cornwall was uncovered by a farmer, who had removed 100 cart loads of earth to lay on his stony land before he had any idea that it was not a natural mound. Then he came on the great cromlech underneath.

Another form of monument was the great standing stone or menhir, one of which, the Longstone on the Down above Mottistone still stands to mark the tomb of some chieftain of, it may be, 4,000 years ago.

The implements of Neolithic man are found all over England, the smooth polished axe head, commonly called a celt (Lat. _celtis_, a chisel), the chipped arrow head, the flaked flint worked by secondary chipping on the edge into a knife, or a sc.r.a.per for skins; and much more common than the implement, even of the simplest description, are the waste flakes struck off in the making. Very few stone celts have been found in the Isle of Wight. The flakes are extremely numerous, and a sc.r.a.per or knife may often be found. They are turned up by the plough on the surface of the fields, in the earth of which they have been preserved from rubbing and weathering. They have however, acquired a remarkable polish, or "patina"--how is not clearly explained--which distinguishes their surface from the waxy appearance of newly-broken flint. In places the ground is so covered with flakes that we can have no doubt that these are the sites of settlements. The implements were made from the black flints fresh out of the chalk, and we can locate the Neolithic flint workings. In our northern range of downs where the strata are vertical the layers of flint in the Upper Chalk run out on the top of the downs, only covered with a thin surface soil. In places where this soil has been removed--as in digging a quarry--the chalk is seen to be covered with flakes similar to those found on the lower ground, save that they are weathered white from lying exposed on the hard chalk, instead of on soft soil into which they would gradually sink by the burrowing of worms. It is probable that these flakes would be found more or less along the range of downs under the surface soil.

In places on the Undercliff have been found what are known as Kitchen Middens--heaps of sh.e.l.ls which have acc.u.mulated near the huts of tribes of coast dwellers, who lived on sh.e.l.lfish. One such was formerly exposed in the stream below the old church at Bonchurch, and is believed to extend below the foundations of the Church.

After a long duration of neolithic times a great step in civilisation took place with the introduction of bronze. Bronze implements were introduced into this country probably some time about B.C. 1800-1500; and bronze continued to be the best material of manufacture till the introduction of iron some two or three centuries before the visit of Julius Caesar to these Islands. To the early bronze age belong the graves of ancient chieftains known as round barrows, of which many are to be seen on the Island downs. Funeral urns and other remains have been found in these, some of which are now in the museum at Carisbrooke Castle. Belonging to later times are the remains of the Roman villa at Brading and smaller remains of villas in other places; and cemeteries of Anglo-Saxon date, rich in weapons and ornaments, which have been excavated on Chessil and Bowcombe Downs. But the study of the remains of ancient man forms a science in itself--Archaeology.

In studying the periods of Palaeolithic and Neolithic man we have stood on the borderland where Geology and Archaeology meet. We have seen that vast geological changes have taken place since man appeared on earth.

We must remember that the geological record is still in process of being written. It is not the record of a time sundered from the present day, but continuous with our own times; and it is by the study of processes still in operation that we are able to read the story of the past.

[Footnote 17: Mr. W. Dale, F.S.A.]

[Footnote 18: See figure 9, p. 79.]

[Footnote 19: See account by R. W. Poulton in F. Morey's "Guide to the Natural History of the Isle of Wight."]

[Footnote 20: Surv. Mem., I.W., 1921, p. 174.]

Chapter XIII.

THE SCENERY OF THE ISLAND--Conclusion.

After studying the various geological formations that enter into the composition of the Isle of Wight, and learning how the Island was made, it will be interesting to take a general view of the scenery, and see how its varied character is due to the nature of its geology.

It would hardly be possible to find anywhere an area so small as this little Island with such a variety of geological formations. The result is a remarkable variety in the scenery.

The main feature of the Island is the range of chalk downs running east and west, and terminating in the bold cliffs of white chalk at Freshwater and the Culvers. Here we have vertical cliffs of great height, their white softened to grey by weathering and the soft haze through which they are often seen. In striking contrast of colour are the Red Cliff of Lower Greensand adjoining the Culvers, and the many-coloured sands of Alum Bay joining on to the chalk of Freshwater.

The summits of the chalk downs have a characteristic softly rounded form, and the chalk is covered with close short herbage suited to the sheep which frequently dot the green surface. Where sheets of flint gravel cap the downs, as on St. Boniface, they are covered by furze and heather, producing a charming variation from the smooth turf where the surface is chalk. The Lower Greensand forms most of the undulating country between the two ranges of downs; while the Upper Greensand, though occupying a smaller area, produces one of the most conspicuous features of the scenery--the walls of escarpment that form the inland cliffs between Shanklin and Wroxall, Gat Cliff above Appuldurcombe, the fine wall of Gore Cliff above Rocken End, and the line of cliffs above the Undercliff. To the Gault Clay is due the formation of the Undercliff--the terrace of tumbled strata running for miles well above the sea, but sheltered by an upper cliff on the north, and in parts overgrown with picturesque woods. The impervious Gault clay throws out springs around the downs, which form the headwaters of the various Island streams. The upper division of the Lower Greensand, the Sandrock, forms picturesque undulating foothills, often wooded, as at Apsecastle, and at Appuldurcombe and G.o.ds.h.i.+ll Park. On a spur of the Sandrock stands G.o.ds.h.i.+ll Church, a landmark visible for miles around.

At Atherfield we have a fine line of cliffs of Lower Greensand, while the Wealden Strata on to Brook form lower and softer cliffs.

To the north of the central downs the Tertiary sands and clays, often covered by Plateau gravel, form an extended slope towards the Solent sh.o.r.e, much of it well wooded, and presenting a charming landscape seen from the tops of the downs. This slope of Tertiary strata is deeply cut into by streams, which form ravines and picturesque creeks, as Wootton Creek, 200 feet below the level of the surrounding country.

While much of the Island coast is a line of vertical cliff, the northern sh.o.r.es are of gentler aspect, wooded slopes reaching to the water's edge, or meadow land sloping gradually to the sea level.

Opposite the mouths of streams are banks of s.h.i.+ngle and sand dunes, forming the spits locally known as "dovers." Some of these, in particular, St. Helen's Spit, afford interesting hunting grounds for the botanist.

The great variety of soil and situation renders the Isle of Wight a place of interest to the botanist. We have the plants of chalk downs, of the sea cliff and sh.o.r.e, of the woods and meadows, of lane and hedgerow, and of the marshes. The old villages of the Island, often occupying very picturesque situations--as G.o.ds.h.i.+ll on a spur of the southern downs, Newchurch on a bluff overlooking the Yar valley, Shorwell nestling among trees in a south-looking hollow of the downs, Brighstone with its old church cottages and farmhouses among trees and meadows between down and sea--the old and interesting churches, the thatched cottages, the old manor houses of Elizabethan or Jacobean date, now mostly farm houses, for which the Island is famous, add to the varied natural beauty.

One of the most characteristic features of the southern coasts of the Island, should be mentioned, the Chines,--narrow ravines which cut inland from the coast through the sandstone and clays of the Greensand and Wealden strata, and along the beds of which small streams flow to the sea. Narrow and steep-sided,--the name by which they are called is akin to _c.h.i.n.k_--they are in striking contrast to the more open valleys of the streams which flow into the Solent on the north sh.o.r.e of the Island. The most beautiful is Shanklin Chine. The cliff at the mouth of the chine, just inside which stands a picturesque fisherman's cottage with thatched roof, is 100 ft. high; and the chasm runs inland for 350 yds., to where a very reduced cascade (for the water thrown out of the Upper Greensand by the Gault clay is tapped at its source for the town supply) falls vertically over a ledge produced by hard ferruginous beds of the Greensand. Above the cascade the ravine runs on, but much shallower, for some 900 yards. The lower ravine has much beauty, tall trees rising up the sides, and overshadowing the chasm, the banks thickly clothed with large ferns and other verdure. Much wilder are the chines on the south-west of the Island. The cascade at Blackgang falls over hard ferruginous beds (to which the beds over which Shanklin cascade falls--though on a smaller scale--probably correspond). The chine above these beds, being hollowed out in the soft clays and sands of the Sandrock series, is much more open. Whale Chine is a long winding ravine between steep walls, the stream at the bottom making its way through blocks of fallen strata.

The cause of these chines seems to be the same in all cases. It may be noticed that Shanklin and Luccombe chines are cut in the floors of open combes,--wide valleys with gently sloping floors; and at each side of these chines is to be seen the gravel spread over the floor of the old valley. It can scarcely be doubted that these combes are the heads of the valleys of the old streams, which flowed down a gradual slope till they joined the old branch (or, rather the old main river)[21] of the Yar, flowing over land extending far over what is now Sandown Bay. When the sea encroached, and cut into the course of this old river, and on till it made a section of what had been the left slope of the valley, the old tributaries of the Yar now fell over a line of cliff into the sea. They thus gained new erosive power, and cut back at a much greater rate new and deeper channels; with the result that narrow trenches were cut in the floors of the old gently sloping valleys. The chines on the S.W. coast are to be explained in a similar way. They have been cut back with vertical sides, because the encroachment of the sea caused the streams to flow over cliffs, and so gave then power to cut back ravines at so fast a rate that the weathering down of the sides could not keep pace with it. The remarkable wind-erosion of these bare south-westerly cliffs by a sort of sand-blast driven before the gales to which that stretch of coast is exposed has already been referred to.

A few words in conclusion to the reader. I have tried to show you something of the interest and wonder of the story written in the rocks. We have seen something of the world's making, and of the many and varied forms of life which have succeeded each other on its surface. We have had a glimpse of great and deep problems suggested, which are gradually receiving an answer. Geology has the advantage that it can be studied by all who take walks in the country, and especially by those who visit any part of the sea coast, without the need of elaborate and costly scientific instruments and apparatus. Any country walk will suggest problems for solution. I have tried to lead you to observe nature accurately, to think for yourselves, to draw your own conclusions. I have shown you how to try to solve the questions of geology by looking around you at what is taking place to-day, and by applying this knowledge to explain the records which have reached us of what has happened in the past. You are not asked to accept the facts of the geological story on the word of the writer, or on the authority of others, but to think for yourselves, to learn to weigh evidence, to seek only to find out the truth, whether it be geology you are studying or any other subject, and to follow the truth whithersoever it leads.

[Footnote 21: See p. 91.]

FOR FURTHER STUDY.

Memoirs of the Geological Survey. General Memoir of the Isle of Wight, date 1889. New edition, ent.i.tled "A short account of the Geology of the Isle of Wight," by H. J. Osborne White, F.G.S., 1921, price 10s.

The Memoirs are the great authority for the Geology of the Island: technical; books for Geologists. The New Edition is more condensed than the original, but contains much later research. Mantell's "Geological Excursions round the Isle of Wight," 1847. By one of the great early geologists. Long out of print, but worth getting, if it can be picked up second-hand.

Norman's "Guide to the Geology of the Isle of Wight," 1887, still to be obtained of Booksellers in the Island. Gives details of strata, and lists of fossils, with pencil drawings of fossils.

Other books bearing on the subject have been mentioned in the text and foot-notes.

An excellent geological map of the Island, printed in colour, scale 1 in. to the mile, full of geological information, is published by the Survey at 3s.

A good collection of fossils and specimens of rocks from the various strata of the Isle of Wight has recently been arranged at the Sandown Free Library, and should be visited by all interested in the Geology of the Island. It should prove a most valuable aid to all who take up the study, and a great a.s.sistance in identifying any specimens they may themselves find.