250 PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. [March 20, 



before this Society, I had not seen these beds in situ, and was ready- 

 enough to accept the suggestions then put forward in regard to their 

 position. Since that time, however, I have most carefully examined 

 the Punfield strata, and find it impossible to agree to the position 

 assigned to them by the author of that paper. 



It is not my purpose at this time to go closely into the details of 

 the section, as I hope to do so on another occasion ; but, with per- 

 mission, I will here state broadly the points of difference between us. 



Taken broadly, the Wealden beds, no less than the succeeding 

 representatives of the Neocomian strata of Swanage Bay, put on a 

 shore- or littoral appearance as compared with their recognized equi- 

 valents in the Isle of Wight; and aU, even on Mr. Judd's own 

 showing, thin out rapidly to the westward. Yet one is asked to 

 believe that the shallow-water, almost purely marine Punfield beds 

 of Punfield are equal in position to the deeper and almost purely 

 freshwater strata of Atherfield and Compton Bay. This seeming 

 contradiction is so far, however, merely a question of probability, 

 and might, but for other reasons, be even as stated. But a far more 

 important point in the Punfield section has been hitherto apparently 

 either overlooked or disregarded ; I refer to the condition of the 

 beds beneath the " marine band," and between that and the so-called 

 *' variegated beds " of the "Wealden. 



The cliff-section, fig. 1, given in Mr. Judd's paper on the Punfield 

 Formation*, illustrates very fairly the position of these intervening 

 strata. The beds are of no great thickness, possibly not more than 

 from thirty to forty feet in all, of which the upper part alone is visible. 

 The whole group, I suspect, is argillaceous. 



My attention was called to this portion of the section by observing 

 the resemblance of the beds beneath the " marine band " to the well- 

 known " Lobster-clay " of Atherfield and Surrey. These beds were 

 but slightly exposed at the time of my visit ; but with some trouble 

 I contrived to trace them from the " Marine band " downwards to a 

 depth of from fifteen to twenty feet, where they rested on a hard seam 

 or stratum of gritty ironstone from one to three inches in thickness. 

 Below this hard stratum the beds were covered for some distance by 

 vegetation ; and the next strata visible were coloured sands and clays 

 of the Wealden. 



The clay between the " Marine band " and the band of gritty 

 ironstone is stiff and nearly uniform in character, and appeared at 

 first sight to be whoUy unfossiliferous. After a long search, however, 

 and by breaking up the dryer masses of the clay, I obtained first 

 traces, and finally crushed but otherwise nearlj^ entire specimens of 

 a truly marine fossil, a species of Aira. Imperfect as were these 

 specimens, I had no doubt that they represented the Area Baulini 

 of D'Orbigny — a species with which I was well acquainted, and 

 which is one of the commonest fossils of the Atherfield clay. 



Beyond this evidence as to the marine origin of the clay-bed my 

 search was unrewarded ; but the suspicion aroused in my mind by 

 the similarity of these clay-beds to the Lobster-clay of Atherfield 

 * Qiiai-t. Journ. Geol. Soe. vol. xxrii. p, 212, fig. 1. 



