8i 



It is certain that the conditions depicted in my figures are not now 

 being produced here, and that the cause which formed them has 

 ceased to act. In the endeavour to explain these appearances, I 

 find that the marks left by the movement of true landslips are 

 of no assistance. The settlement of sea cliffs or those of 

 artificial cuttings are not comparable with them, nor have the 

 sections I have made, or been able to examine, in the slipping 

 material, presented the peculiarities under consideration. The 

 contortions of the neighbouring Boulder clay, of Glaciers, and 

 of those so famous in the Cromer Cliffs, are altogether different. 

 I do not think that the sliding of bogs or sheets of " vegetable 

 spongy matter," full of water (Dr. Coppinger's soil cap) without 

 the aid of intense frost capable of producing the effect. There 

 is, however, in our neighbourhood, one situation in which the soil 

 creeps and slips now, viz., on the steep hill sides formed of stiff 

 clay, such as Shooter's Hill. 



The clay contracts in summer, shewing deep and long cracks. 

 When winter arrives these are filled with water and the whole 

 surface clay becomes saturated with it. A frost expands the 

 crack and the whole substance of the soil, thus pushing the clay 

 a little down hill and forming a roll or fold. A thaw fills the 

 widened crack with water and the process is repeated. Then a 

 little pond is formed behind the ridge and its greater volume 

 increases the leverage of the expanding mass of ice and adds 

 its extra weight of water in the fissure when thawed. We can 

 see that these alternate acts of freezing and thawing may produce 

 resemblances to my figures, but it must be remembered that the 

 modern action is different to the ancient, and that it is confined 

 to clays and steep hill sides. Moreover, in the sections I have ' 

 cut through the modern folds, the pleatings of the parent rock 

 are absent. 



Therefore I suppose, Firstly, that the folds or Underplight, with 

 the puddled sludge or Trail, may have resjilted from the heavy 

 pressure of a superincumbent mass of s?iow on a soil in a 

 condition capable of yielding, and frequently repeated. 



It is a familiar fact that the ground softens beneath the winter 

 snows, and that plants grow beneath them. Long before the 

 heavy sheets of Arctic snow are melted, and even when they do 

 not disappear, the ground beneath is softened. 



opinion held by many who should know better, but the disentanglement 

 of the stones by the rain is too slow a process for some minds to perceive, 

 they see more stones but they don't see less clay. 



