Ivi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



nected with them. How far these great changes in various parts of 

 the earth's surface mayhaveheen sometimes very gradual, at othertimes 

 marked by great local disturbances, remains to be carefully ascertained. 

 We seem to possess good facts respecting some of them, but it will be 

 evident that we must wait for very careful examinations of many re- 

 gions, including some supposed to be fairly known in this part of the 

 world, before we can gather together sufficient data on which to rea- 

 son correctly even respecting the European area. 



From Mr. Prestwich we have had additional information respect- 

 ing the tertiary accumulations of Southern England, in a paper " On 

 the Position and General Characters of the Strata exhibited on the 

 Coast Section from Christchurch Harbour to Poole Harbour." In this 

 communication, after alluding to the change apparent in the lower 

 tertiary or eocene beds between the sections exposed at Alum Bay 

 and Whitecliff Bay, and to the descriptions of the coast he was about 

 to notice by Sir Charles Lyell, he proceeded to consider the relations 

 of the beds seen to the Barton clay, and to make some remarks on 

 their physical conditions. Reference was made to the interest af- 

 forded by the physical structure of the district, so much variation 

 in the deposits of the same age being observable. It is pointed out, 

 that while, on the east of the Isle of Wight, the series of accumula- 

 tions between the London and Barton clays consist of a thick repe- 

 tition of sands and clays, in which '' the absence of strong drifts is 

 denoted by the abundant fossils and by the beds of shells in their 

 normal position, uninjured as at the moment of their entombment," 

 and vegetable remains being scarce, at Alum Bay the case is diifer- 

 ent. There " the remains of drifted vegetables are common ; the 

 strata are strongly marked, — fresher, as it were, from their source ; 

 exhibit the action of stronger drifts, and do not contain a single fossil 

 to represent the 200 species abounding in the synchronous strata at 

 so short a distance eastv/ard." 



Following up this view, Mr. Prestwich points to still further 

 irregularities of accumulation towards Poole, indicating an approach 

 to the sources of the transport of detritus into the seas of the time, 

 and calls attention to the geological interest arising from a proper 

 study of the ancient physical conditions obtaining at the period of 

 these deposits, however barren and unattractive they might at first 

 sight appear. 



Researches of this kind are in the right direction. By them we 

 shall gradually approximate towards the causes of difference or re- 

 semblance observable in the accumulations of equal geological times, 

 — not only as respects such tertiary deposits as are here noticed, but 

 those of various ages, — which are so needful to consider when we 

 endeavour to account for the spread of varied mineral accumulations 

 over wide as well as minor areas. By carefully weighing the evi- 

 dences afforded of the physical conditions of given times with those 

 of the contemporary animal and vegetable life, by no means neglect- 

 ing the position as to latitude on the earth's surface of any deposits 

 examined, we may hope to attain a far greater knowledge of the re- 

 lative disposition of land and water, of climates, and of the spread 



