1872.] MEYER PUNFIELD SECTION. 71 



Purbeck was superior in position to the " Lobster-clay " of Ather- 

 field — or (to state the matter more clearly) that the Punfield beds, 

 from the " marine band " upwards, were Lower Greensand instead 

 of Wealden, representing, however, only so much of the Lower 

 Greensand of the Isle of Wight as would be included between the 

 " Lobster-clay " and the Gault. 



The assertion was a bold one, and should, I am well aware, 

 have been supported at the time by fuller evidence. It was not, 

 however, put forward thoughtlessly ; and I have now to offer such 

 further evidence as may tend towards a settlement of the points 

 in question. 



To test the truth or error of my impressions with respect to the 

 relation of the Isle-of- Wight Wealden and Neocomian strata to 

 those of Punfield, I revisited the coast-sections at Redcliff and 

 Atherfield, and spent several days in studying the corresponding 

 strata in Compton Bay. I sought carefully in either formation 

 for such change in its passage westward as might indicate the 

 relation of either to the marine, or semi-marine, Punfield beds of 

 the Isle of Purbeck. 



The Wealden beds showed no such change. But for slight variations 

 in thickness and disposition, these Upper Wealden shales of the Isle 

 of Wight are almost perfectly alike at Compton Bay, at Sandown, and 

 at Atherfield. The section of the Wealden strata of Compton Bay 

 has been already given with great accuracy in the Memoirs of the 

 Geological Survey*; and on this point it is therefore needless to enter 

 into detail. 



Unlike the Wealden, the condition of the Greensand strata of 

 Compton Bay is much altered in appearance from what may be seen 

 at Atherfield. Their upper and middle portions are extensively and 

 distinctly laminatedf , and put on already very much the appearance 

 of the more laminated portions of the Punfield strata. They contain 

 more lignite and apparently fewer fossils in comparison than the cor- 

 responding strata at Atherfield. The " Crackers rock " is scarcely 

 recognizable at Compton, its position being merely indicated by semi- 

 indurated nodules of shell-rock. The " Lobster- clay," however, is, 

 fairly represented ; and although the Perna-bed and underlying 

 grit, or passage-bed, are nowhere visible at their outcrop, on account 

 of the fallen masses of the low undercliff, their presence at this point 

 has been long since satisfactorily determined. Masses of the grit- 

 bed, with its characteristic Neocomian fossils, may be picked up 

 abundantly along the shore. 



So far, then, the evidence obtainable from the Wealden and Neo- 

 comian strata in their most westerly exposure in the Isle of Wight 

 tended mainly to strengthen my previous belief as to the real position 

 of the Punfield beds of Punfield. The next step to be taken was to 

 reexamine the Punfield Section, and to obtain fuller evidence, if 

 possible, as to the condition of the strata beneath the so-called 

 " marine band." 



With this intent I returned to Punfield towards the end of October, 



* Mem. Geol. Surv. (Geol. I. of Wight), chap. iii. p. 9, fig. 7. t Ibid, p. 9. 



