370 



KNOWLEDGE & vSCIENTIFIC NEWS. 



[March, 1906. 



Coast Denudation in 

 E^ngland. 



V>\ 1U>\VARD A. Martix, I'.Ci.S. 



Part II. 

 As already pointed out, no part of the coast has suffered 

 more greatly than where the cliffs consist of deposits 

 of looselv-compacted sand and clav, and as scarc<_'ly any 

 i^eolotvical formations other than of tertiary and 

 quafernar}' ago arc found in ihis condition, hence it is 

 where fhc.se deposits arc <'xpost'd to the sea-;\clion th.it 

 the cr()sion is most felt. 



I'rohahly nowhere has denudation proceeded mori' 

 ra])idly Ihan on the Holderncss coast of \'ork-shirc. 

 N'arious estimates have been framed of the extent to 

 which the coast suffers in this part, and the encroach- 

 ment of the sea has been estimated at so high a figure 

 as 30 feet, and liy others at so low a one as 6J feet, per 

 annum. Probably an average rate would be found in 

 that estimated by Mr. T. Sheppard, F.G.S., for the 

 coast between Spurn Head and Bridlington, namely, 

 7 feet per annum. Between the.se two many ancient 

 villages have disappeared — Wilsthorpe, Auburn, Hart- 

 burn, Hyth, Cleton, Monkwell, &c. — and in some ca.ses 

 the nruncs remain only as applied to modern spots which 

 were formerly inland. Observations which have been 

 made at Dimlington show that during the last few years 

 the average yearly rate of erosion has been loi feet, 

 and at Out Newton some ruins of an old chapel may he 

 .seen which were, in 1833, 147 3'ards from the edge of 

 the clifl. .South of Kiln.sea, where the low boulder-clay 

 cliffs are about 10 feet in height, the cliff dies away 

 altogether, and were it not for the protecting groynes 

 which have been built by the Board of Trade, erosion 

 here would probably be considerably greater than it 

 now is. Mr. E. R. Matthews has made some interest- 

 ing calculations as to the weight and extent of the area 

 denuded. Many estimates have been made, and the.se 

 will always differ to a very great extent, depending in 

 the first place on the assumed rate of denudation, then 

 the average taken for the height of the cliffs, and the 

 average weight per cubic foot of the materials con- 

 stituting the glacial beds of which the cliffs are formed. 

 The estimated weight of the deposits removed has been 

 placed at three millions of tons per annum, whilst Mr. 

 Matthews places the area which has disappeared since 

 55 B.C., the date of the Roman invasion, at 115 square 

 miles, or nearly the equivalent to that on which London 

 and Greater London stands. Looking at it all from a 

 geological point of view, one must bear in mind that 

 the sea is only now encroaching upon what formerly 

 belonged to it. The deposits which are now suffering 

 are accumulations of boulder-clay and glacial moraines 

 which had no existence in tertiary times, and up till the 

 beginning of the glacial period the coast-line ran con- 

 siderably further inland than that to which the .sea has 

 even now attained. The .sea at that time approached 

 closely the line of the eastern boundary of the chalk, 

 which runs south-west from Flamborough Head in the 

 direction of Driffield and Beverlcv. 



An interesting question which has puzzled ob.servers 

 is. What has become of all the eroded material? The 

 silting-up of the Humber is, to a large extent, due to 

 its deposition, together with the growth of Spurn Head; 

 and as it is denied by some authorities that any of the 

 silt is carried forward to the Lincolnshire coast, it 



would .seem to follow that protective measures, if taken 

 effectively along the whole of the Holderness cotist, 

 would go a long way towards keeping a fair-way 

 alwa3's open in the Humber Channel. 



Another portion of our eastern coast-line which is 

 suffering at the present dav, and has, indeed, suffered 

 • IS long as history can record, is that which extends 

 Irom the northern coast of Norfolk along the .Suffolk 

 and I'^sscx coasts to the Thames estuary. These, again, 

 expose to the sea cliffs of but a partially-coherent 

 material, affording little or no protection to the batter- 

 ing-ram action of the waves. The deposits here formed 

 are partly of glacial age, chalky boulder-clay being the 

 principal material, and partly of Pliocene age (late 

 Terliary), the latter being known as the " crag " forma- 

 tion. In Essex the London Clay (Eocene Tertiary) has 

 cropped out from iM'neath the crag, and this, although 

 of a more coherent nature than the other deposits luen- 

 tioned, affords but little more resistance to the crfiding 

 power of the .sea. So when one leaves the chalk of the 

 north of Norfolk we see, going southward, a gradual 

 falling away in a south-westerly direction of the coast- 

 line, and this only comes to an end when we reach the 

 Thames, whilst on the south side of the estuary we find 

 rai.sed as a bulwark against similar denudation the up- 

 rise of the chalk. Tlie fault which occurs in the bed of 

 the river, and which has let down the strata on the 

 north side to a lower level than tho.se on the south, 

 besides probably deciding the position of the em- 

 bouchure of the river, has exposed the low-lying 

 northern coast to the immediate action of marine de- 

 nudation. Thus the whole East .-Xnglian coast is sub- 

 ject to continual erosion. 



A map is preserved in the Yarmouth Town Hall, 

 copied in the time of T'"lizabeth from an earlier one, 

 which purports to show the coast hereabouts as it was 

 in the year 1000. At that date the site of what is now 

 Yarmouth appears to have been but a sandbank across 

 the entrance to a wide estuary, extending up to Harles- 

 ton and Norwich. Considerable concern is now felt lest, 

 by the removal of the comparatively narrow line of 

 cliffs, a similar state of affairs may ag'ain come into 

 existence, and the low-lying land of East Anglia be- 

 come permanently flooded. 



We have seen that Holderness has probably come 

 into existence since the glacial period, and in these 

 eastern counties again we see wide stretches of low- 

 lands inter.sected by broads and sluggish streams, 

 which show to the practised eye that the period is not 

 far away back in geological time when the sea stretched 

 away inland, covering those parts where subsequently 

 the boulder-clay came to be deposited. The question 

 of erosion is a burning one, but it must be borne in 

 mind that a considerable area was wrested from the sea 

 in those pre-historic times, when Britain's natives wit- 

 nessed the passing away of the glacier mantle which 

 had covered so much of the country. 



Although the coast of Essex has no doubt suffered 

 much in the past, and the products of its denudation 

 have been spread o\cr the sea-bottom in such a way as 

 to shallow the sea for some considerable distance from 

 the land, modern erosion is not now so .serious a matter 

 as it must have formerly been, in view of the extensi\c 

 mud flats over which the incoming tide pursues its way. 

 But when one sees the evidences on all hands along the 

 coast of the former existence of a much greater popula- 

 tion than is now there to be found, there is good reason 

 to think that many a flourishing \illage has been lost in 

 the sea. The spreading out of the debris in the form 

 of mud flats leads in the course of time to a contrary 



