374 Mr. Lyell on the Boulder FoTination, 



site of parts of Norfolk and Suffolk, including the eastern 

 coast of Norfolk. Into this estuary or bay one or many 

 rivers entered, and in the strata then formed were imbed- 

 ded the remains of animals and shells of the land, river, 

 and sea. Certain parts of this area seem at length to have 

 been changed from sea into low marshy land, either be- 

 cause the sea was filled up with sediment, or because its 

 bottom was upheaved, or by the influence of both these 

 causes. Two consequences followed : first, trees grew on 

 some spaces gained from the sea ; secondl}^, in other spots 

 freshwater deposits were formed in ponds or lakes, and in 

 the channels of sluggish rivers, or grounds occasionally 

 overflowed by streams. Next succeeded a period of gra- 

 dual subsidence, by which some of the lands supporting 

 the forests were submergetl, the trees broken down, and 

 their roots and stumps buried under new strata. At the 

 same time, the freshwater beds, whether resting on crag or 

 immediately on chalk, became covered with drift, except in 

 certain places, such as Mundesley, where for a small space 

 the accumulation of drift seems to have been entirely pre- 

 vented, perhaps by the continued flow of a small body of 

 freshwater. 



1 have met with no fossils so imbedded in the drift as to 

 entitle me to form any positive opinion whether it be of fresh- 

 water or marine origin. The regularly stratified arrangement 

 of a large part of it, and the different materials of the alter- 

 nating strata, clearly demonstrate that it was formed gradually, 

 and not by any single or sudden flood. The boulders which 

 it contains, some of large size, seem to imply, that while a 

 great proportion of the mass may have been derived from 

 neighbouring regions, part at least has come from a great 

 distance. Mr. R. C. Taylor observes, that the shore to the 

 west of Cromer exhibits a singular accumulation of travelled 

 fragments of rocks, whence it would not be difficult to collect 

 a tolerably illustrative series. They consist chiefly of rounded 

 blocks of granite, basalt, porphyry, trap, micaceous schist, 

 sandstones of various kinds, chert, breccia, besides limestone 

 and claystone ; also fragments derived from the chalk, plastic 

 clay, London clay, green sand, Kelloway's rock, the oolites, 

 lias, and marlstone; in fact almost every formation above the 

 coal-measures. These, he says, are of all intermediate mag- 

 nitudes up to four tons weight, lai'ge bouldered masses ap- 

 pearing in the sea at low water, lying mixed with flints upon 

 the chalk. One block of granite is stated to be near six feet 

 in diameter, and another mass, standing six or eight feet high, 

 has for some years been known to the fishermen under the 



