1849.] AUSTEN ON THE VALLEY OF THE ENGLISH CHANNEL. Il 



Island coast fauna, and which lives just below ordinary low-water, 

 has its fragments carried out fifty miles from the nearest coast ; with 

 it, and abundantly, is Patella vulgata. 



The general character of the sea-bed of the Channel is, that its 

 component materials become finer as the distance from the coast-line 

 and the depth of water increase. This relation of sea-bed to depth 

 was long since noticed. In Lord Anson's 'Voyage' (1740-47) he 

 states that he has tried soundings more frequently, and in greater 

 depths, and with more attention than had been done before, and from 

 the remarks occasionally made on their value, and the occasions on 

 which they were taken, he seems to have relied on them when navi- 

 gating unknown seas, as a sure indication of his distance from some 

 land. His observations give 



80 — 60 fathoms fine sands, mud and ooze, 

 60 — 40 „ sands with broken shells, 

 40 — 12 „ coarse sands, pebbles and small stones, 

 and appear generally to have been taken along lines of open coast. 



These numbers are not here produced as the rule or scale of depths 

 regulating the distribution of materials by the sea. But if we take 

 lines of soundings seaward, we shall invariably find a progressive 

 change as we advance from deep water and open sea, from mud to mud 

 with sand, next sands which increase in coarseness ; small subangular 

 pebbles ; and across beds of water-worn materials, described as of 

 the sizes of peas, coffee-berries, beans, almonds, pigeons' eggs, &c., 

 till we finally reach the marginal banks of gravel and shingle ; so that 

 the term soundings is well made to designate both the depth of water 

 and the nature of the sea-bed — the condition of the one being the 

 result of the action of the other. The bearing of this relation of sea- 

 bed to depth, to what forms the greater part of the detail of pure 

 geology, is obvious : the vast series of sedimentary deposits, nearly 

 the whole of our areas of dry land, are the aggregates of the soundings 

 of ancient seas, presented to us in their progress through long periods 

 of time*. 



Among the more interesting points connected with the subject of 

 the older sedimentary deposits, are those known in descriptive geology 

 as — § 1. Mineral character; § 2. Stratification; and § 3. Sequence 

 of deposits. 



§ 1 . Mineral character is simply the result of the process of distri- 

 bution by a body of water in constant motion — an operation, the pre- 

 cise counterpart of what is employed in various economical processes 

 whereby mixed materials are separated, arranged and carried forward 

 according to size and specific gravity. The divisions on the Map of 



* I had long since entertained the notion that geological speculations might be 

 greatly assisted by a careful study of any given area of sea-bed (Geol. Trans, vi. 

 p. 454), and the notes from which this paper has been drawn up date back many 

 years ; but I am ashamed to confess that at the time it was communicated to the 

 Society I had not read Mr. Darwin's Observations on South America : the whole 

 work is a rich store of facts and correct inferences, and as bearing on the ob- 

 servations contained in this part of my paper, I would refer to Mr. Darwin's 

 first three chapters, and more especially to the first. — December 1849. 



