Day — Ancient Beach and Submerged Forest. Ill 



yet their connection witK tlie raised beach, is so clearly suggested by 

 their relative position, that I was altogether bewildered when I 

 found, on reference, that D'Archiac' assigned them to the older 

 Tertiary. The third component of the group is, in character, an 

 excellent example of what De la Beche,^ in his description of raised 

 beaches, termed a "head;" in position, however, it is far removed 

 from any cliff or steep elevation whence the angular fragments could 

 have fallen, whilst they also seem too large to be a "rain- wash ;" so 

 that, in spite of its appearance, the observer is forced to the conclu- 

 sion that the materials of which it is composed have been transported 

 from a distance ; but, by what agency ? 



Whilst the appearance of this raised beach and its accompaniments 

 was still fresh in my mind, I chanced to be examining the coast 

 between Wissant and Cap Blanc-nez, when I was much struck by 

 the peculiar appearance of a recent formation, which forms part of a 

 low cliff between the former place and the little hamlet of St. Pol. 

 North of a stream that descends from Sombre-Haute and finds its 

 way through the Sand-dunes to the sea, at about half a mile from 

 Wissant, large blocks of grit, resting upon dark-green sands, and 

 some underlying dark clays, indicate the presence of the Lower 

 G-reensand Formation beneath the shore. The higher part of the 

 " between -tide-marks " is here covered by flint-shingle, and at high- 

 water level a bed of shingle, of ancient origin, begins to crop up 

 into sight, from which evidently the flints of the present beach are 

 derived. At first the characters of the old beach are not distinctly 

 seen ; but as the observer proceeds in a north-easterly direction, 

 and the Greensand and the Gault form a gradually-rising, low cliff, 

 he will perceive the recent accumulation well exposed, capping the 

 Secondary strata and interposed between them and the Sand-dunes. 

 At the time of my visit it could be clearly traced for 500 paces, and 

 beyond that distance I do not think that it exists ; though it may do 

 so, and be concealed by the fall of sand and debris from above. At 

 the point where it ceases to be visible, its base is at least 15 feet over 

 the highest shingle of the shore ; so that it rests upon a gradual 

 slope, having a regular inclination of about 1 in 64, in a south- 

 westerly direction. Where it is best exposed, the formation presents 

 the following sequence of characters, and displays the section given 

 in the accompanying figure (Plate VII. Fig. I.). 



A bed six feet in thickness of chalk pebbles and rolled flints 

 (Fig. I. 6) rests dii-ectly upon the Cretaceous strata; towards the 

 northern end the chalky element rather predominates, the flints 

 being here most thickly packed in the middle of the bed, and more 

 scattered above and below ; where, however, it comes down towards 

 the present beach, there is less of the Chalk, and the bed is more 

 exclusively composed of flints. As far as I noticed, the materials 

 are not cemented together ; and this, at first sight, led me to think 

 that the accumulation was an equivalent of the Chalk-rubble or 



^ D'Archiac Histoire des Progres de la Geologie, T. 4, p. 200. 

 2 Eeport on Geology of Cornwall, etc., p. 432. 



