On the Beds at Headon Hill and Colwell Bay in the Isle of Wight

Abstract

I. I ntroduction . In a recent; communication laid before the Society the opinion was expressed that a serious error had been made by almost all previous writers in regarding the marine beds at Colwell Bay and Headon Hill as on the same geological horizon ; we read:—“We shall now demonstrate that the Colwell-Bay marine beds are not, as has been hitherto supposed, the equivalent of those of Headon Hill and Hordwell Cliff, but that they occupy a distinct and much higher horizon.” Upon the correction of this supposed error a new classification and nomenclature for the Upper Eocene formation of Britain was proposed. The author further, after a review of the palæontological evidence, arrived at the conclusion that, on the one hand, the fossils in the Headon Hill and Hordwell Cliffs were identical, while, in the second place, those of Colwell Bay, White Cliff, and Brockenburst presented the closest agreement among themselves. Then, comparing the former two localities, taken together, with the latter three, taken together, he considered (1) that the fauna of the first group was largely estuarine, and that of the second group marine; (2) that less than half the forms found in the former occur in the latter; (3) that the fauna of the former approximated more to that of the Barton beds, having about one third in common with them, while not more than one fifth of those from the latter three localities occur at Barton; (4) that the fauna of the former two agreed with that