Mr. Lyell on the Boulder Formation^ 
iiorizontal beds, and apparently the till also, of which the sur- 
face is so even, have not participated in these movements even 
in the smallest degree, we are compelled to suppose that some 
lateral force has been exerted against the upper masses of 
drift which has not been applied to the lower ones. Yielding 
beds having a thickness of at least 15 or 20 feet must in some 
cases have been subjected to this sideway pressure and moved 
bodily ; and it is impossible to conceive that any original irre- 
gularity in the mode of deposition, nor any shrinking or set- 
tling of the materials, nor anything in short but mechanical 
violence, could have produced such complicated folds. Com- 
monly we are in the habit of attributing such movements to 
a subterranean force acting from below, but it is difficult to 
imagine how such agency could have disturbed the overlying 
beds without affecting the subjacent. I shall defer to the se- 
quel the consideration of the various hypotheses which may 
be suggested to account for such appearances, first describing 
other irregularities and apparent anomalies which present 
themselves in this same line of cliffs. 
At one spot between Bacton and Mundesley, where the 
cliff is 50 feet high, I observed at a depth of 30 feet from the 
top, a small pit or furrow as it were cut into strata of blue 
clay, and filled with fragmentary white chalk and chalk flint, 
regular strata of sand and loam being superimposed. This 
indentation was four feet deep and six wide, and precisely 
resembles those irregularities which we see in superficial 
gravel ; and they may all be explained if we suppose, that 
during the subsidence which is indicated by the buried forest, 
the drift of the mud cliffs was formed in very shallow water, 
so as to be exposed to the denudation of small streams or 
currents, by which narrow grooves and hollows were exca- 
vated, then filled with drift, and then, after the sinking of the 
whole, overspread with regular strata. 
Freshwater Strata at Mundesley . — Both to the north and 
south of Mundesley, the cliffs, varying in general from 40 to 
70 feet in height, consist in their lower part of blue clay or 
till, covered with stratified yellow sand and loam ; but at the 
town of Mundesley itself the cliff’ lowers to a height of be- 
tween 20 and 30 feet, and for several hundred yards is occu- 
pied by a freshwater deposit, covered with about 10 feet of 
flint gravel. 'Fhe freshwater beds consist of brown, black, 
and grey sand and loam, mixed with vegetable matter, some- 
times almost passing into a kind of peaty earth containing 
much pyrites. A few layers also of gravel occur composed 
of rounded flint pebbles. These beds are often irregular arui 
rarely continuous for great distances. The bottom of the de- 
