Strata of the Islands of Seeland and Moen. 257 



two formations may be explained by supposing the convulsions to have 

 happened at the bottom of the sea when the chalk was already overspread by 

 the boulder formation, which may sometimes have slid down bodily and in 

 stratified masses into rents which opened beneath them. The superior de- 

 posits seem to have been swallowed up in the same manner as houses and 

 villages have been suddenly engulphed by modern earthquakes, and the 

 upper parts of some chasms may occasionally have closed in again. These 

 movements have produced sharp curves in some places, and in others great 

 faults in the strata of chalk, which are beautifully marked by the lines of 

 black flint. Occasionally a mass of chalk divided by regular layers of inclined 

 flints abuts abruptly against another, in which no flints or scarcely any are 

 visible. Almost every other imaginable form of dislocation may sometimes 

 be met with. I did not see any flints shattered in situ, and I am told that 

 they have rarely been observed ; but I cannot agree with Dr. Forchhammer 

 in the inference which he draws from this fact, namely, that the flints were 

 not fully se|)arated from the calcareous matter when the convulsions hap- 

 pened*. 1 can however readily believe, that they were less brittle when be- 

 neath the sea, as they probably were more impregnated with water than now. 



It is well known, that in the English clifls near Trimmingham, in Norfolk, 

 large masses of chalk are surrounded and nearly enveloped in the sands and 

 clays associated with the crag. These appearances are strictly analogous to 

 the phenomena of Moen above described ; but in Norfolk they are on a much 

 smaller scale. In both cases, they compel us to assign a comparatively modern 

 date for an era of partial but violent convulsion, by which the chalk has been 

 deranged. 



The projecting mass of solid chalk generally seen at the base of the clilTs, 

 sometimes more than fifty feet high, and sloping like a talus, may perhaps in- 

 dicate a diff'erent rate of movement at which the land rose at different periods 

 from the sea. The elevation after proceeding rapidly for ages may have 

 ceased, so that the waves had time to encroach and shape out a vertical cliff, 

 after which the upheaving process may have been resumed, and what was 

 previously a submarine ledge of rock may then have emerged. What we now 

 see may be the remains of such a ledge, which the sea has not yet had time to 

 sweep away entirely, except in a fevv places. Or, on the other hand, the rate of 

 emergence of land may have been uniform, and the inferior mass of chalk 

 harder than the upper, in which case it would resist the action of the waves 

 for a longer period. Of this greater hardness however of the lower mass, 

 neither 1 nor Dr. Forchhammer obtained any proof. 



* See his paper published at Copenhagen, Nov. li, 1835. 

 VOL. V. SECOND SERIES. 2 L 



