Figure 4.-Section exposed in Worborrow Bay.
2. Worborrow Bay. I have not been able to find any inland sections in the Isle of Purbeck which throw light on the Punfield formation. But at the western end of the peninsula, in the cliffs of Worborrow Bay, 11 miles distant from Swanage Bay, we find another exposure of these beds. At this place the Chalk, Chalk-marl, Upper Greensand, and Gault present the same characters as in Punfield Cove, and, as there, are inclined at a high angle (fig. 3) *.
The Upper Neocomian (" Lower Greensand") is represented by about 40 feet of clays, sands, and ironstones. From these beds I obtained a fine specimen of the highly characteristic Panopoea neocomiensis.
The Punfield formation is here about 65 feet thick. No trace of the blue clays with limestone bands oyster-beds and " beef" is found in its upper part; but its whole thickness is composed of interlaminated clays and sands, with lignite and bands of iron- stone containing a few apparently marine shells. At the base is a very distinctly marked bed of ironstone of a dark reddish-brown colour, containing casts of shells, which were recognized by Prof. Edward Forbes as marine. The presence of this bed is recorded in a note on the Map of the Geological Survey. The general succession of the Punfield-beds at Worborrow Bay is as follows : —
that he has examined the Punfield section and found a single specimen of the genus Area, the species being indeterminable, some feet below the Marine Band. This discovery is interesting as a fresh proof of the gradual nature of the change from freshwater to marine conditions.
- See also Sir Henry Englefield's ' Isle
of Wight,' Plate 37, No. 1.
