﻿1851.] AUSTEN ON THE PLEISTOCENE PERIOD. 121 



changes of level which can with any fitness be referred to what may 

 be considered as a "recent period." When we bear in mind the 

 great extent of the area of the English Channel which is comprised 

 within lines connecting the several places which have been here 

 noticed, we may safely infer that this last change has been a uniform 

 one throughout. Without entering into unnecessary details with re- 

 spect to areas beyond the English Channel, it may be stated generally 

 that there is abundant evidence of a like change of relative level of 

 small amount, over that of the German Ocean. 



§ 2. The next level, in chronological order, at which we meet with 

 evidence of a former reach of the sea-margin, is in position (d) on 

 sections No. 4. PL VI. and fig. 1 : we there constantly find sea-sands, 

 thin seams of pebbles, and shingle, with the common shells of the coast. 

 The thickness of these beds is never very great, and at elevations of 

 30 feet they show clear indications of belonging to the upper marginal 

 sea-zone. They become distinct only when they rest on the summit 

 of the accumulations to be next described ; where they come in con- 

 tact with older sea-beds, the line of separation is not usually clear. 

 The older sea-beds are more consolidated, and their upper surfaces 

 are worn smooth in places. Instances of this level are to be seen 

 in the coast-sections west of Falmouth, and in those of the Prawle 

 and Start district, to which the foregoing observations more parti- 

 cularly apply ; here the upper portion is often included in the band of 

 dark vegetable mould, unless where local circumstances have favoured 

 the subsequent accumulation of earthy materials. Marine beds of 

 this age occur in the Channel Islands' sections (fig. 2, d). 



The estuarine deposits which would be the equivalents of the 

 sea-beds of this level are those seen in the Pentuan section (No. 1 . 

 PL VI.), with which those of the other valleys of the West accord. 



These beds are clear indications of another sea-level perfectly di- 

 stinct from, and show a depression of the land of somewhat greater 

 amount than, that of the lower level previously noticed. If some of 

 the high level accumulations of shingle of the Lizard district are 

 rightly referable to this period, as I am disposed to consider them 

 for reasons which will be assigned when considering the beds next in 

 descending order, the levels at which the beds of this age occur are 

 not so uniform as those of the period last described. The subsequent 

 rise of the land appears to increase as we proceed westwards. 



§ 3. The accumulation of materials next in order on the typical 

 section No. 4. PL VI. (2. Subaerial beds) occurs in a vast number of 

 sections to be observed along the coasts of Devon and Cornwall ; it 

 has not entirely escaped observation, but as far as I can find, has 

 only been incidentally noticed, and generally under the vague term of 

 "head." 



These beds, wherever found, are remarkably uniform in their gene- 

 ral appearance and composition : they consist of fine earthy matter, 

 such as would result from the decomposition of the rocks of the place ; 

 mixed with this are fragments of rocks of all sizes, ranging up to 

 blocks of considerable dimensions : the fragments are obviously 

 smaller in the upper portion of these accumulations than in the lower. 



VOL. VII. — PART I. K 



