ox THE EROSION OF THE SEA-COASTS OF ENGLAND AND WALES. 371 



7. — Second and Concluding Rejmrt on the Erosion of Dover Cliffs, from Si. 

 Margaret's Bay to Folkestone, a distance of about eleven miles, addressed 

 to the Committee, Mag 1893. Bg Captain S. Gordon McDakin. 



The cliffs, composed of chalk, reach an elevation of 5'25 feet on tlie 

 west at Folkestone, and 400 feet to the east of Dover, to about 200 on 

 the south side of St. Margaret's Bay ; the High Light, South Foreland,, 

 374 feet ; and 88 to the north of St. Margaret's Bay. 



The coast has been compared with the 6-inch Ordnance map of 

 1876, and marked at twenty-four principal stations and eleven inter- 

 mediate ones with marks at about 2 feet above the shingle on plane of 

 marine erosion : these marks are bore holes 3 inches deep by ^ inch wide. 

 This form was chosen as not so likely to be tampered with as other 

 marks, and because they would be difficult to imitate without a specitul 

 tool. Each year has a different mark. 



1890 1891 1892 1893 



O • • O • O • 



. . . . ■ 



The hole with the circle drawn round it is the test-hole, the others are 

 only indicating marks. 



As in the former reports for 1890-1891,. the changes are rather those 

 of the undercliff than the cliffs themselves ; this applies especially to the 

 Folkestone Cliffs and West Cliffs, Dover. 



In last year's report the foretold likelihood of a slip has been con- 

 firmed by a tremendous fall from the Abbot's Cliff, which is here 450 feet 

 in height, amounting to many thousands of tons. 



To the east of Dover (Cornhill) stations iSTos. 5 and 6 in soft 

 white chalk have lost half an inch in twelve months. Stations 1, 2, 3, 

 and 4, in hai'der beds, particularly that of No. 4, in very hard nodular 

 chalk, e.Khibit little or no erosion. 



West Cliffs, Dover. — The sea has here attacked the undercliff and 

 talus. The marks 1, 2, 3, 4, on large detached block, have disappeared 

 by the block having been overturned, displaced, or buried, the actual 

 erosion of the surface not amounting, on an average, to more than about 

 half an inch in twelve months in exposed situations, and washed by every 

 tide. At No. 6, a large detached mass, the marks of last year (1S92) 

 are intact on two faces. 



Folkestone Cliffs. — Great inroads have been made on the undercliff 

 of the Warren in three years. The mark at Station No. 1, lost sight 

 of last year, was found again, even the mark .". of 1890 being intact, 

 although 2 and 3 have disappeared. At No. 4 last year's mark 

 (. . . 1892) also was intact, but 5 and 6 are lost or covered by falls of 

 the cliff. 



St. Margaret's Bay, four miles east of Dover. — South side of bay, 

 mark at Station No. 1 disappeared. Stations 2 and 3 intact, but a 

 soft band of chalk close to beach is here very much undercut by the sea, 

 so that large masses may be expected to fall. North side of bay, mark 

 at Station 1 of last year (. . . 1892) had been tampered with, an attempt 

 having been made to cut it out ; but taking the general surface and depth 

 of hole, the marine erosion was imperceptible. Stations 2 and 3, only 

 reached by storm-waves, were intact. The cliffs are here quite perpen- 



B B 2 



