Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/341

 and delight recognized in them the fauna of the coal-bearing beds of Utrillas, in eastern Spain, which has of late years been made known to us by the works of Vilanova, de Verneuil, Coquand, Collomb, and de Loriere. I should, perhaps, mention that in 1850 no description of these Spanish beds had, so far as I know, appeared.

Believing the subject one worthy of careful study, I have devoted my attention to it for some time past, and embody the results in the present memoir. In the execution of my task I have been furnished with much valuable information and advice by Sir C. Lyell, Mr. Godwin-Austen, Mr. Hulke (who in 1866 examined the beds and made a collection from them), Mr. Wilcox, of Wareham, and my colleagues Messrs. Etheridge, Bristow, and Whitaker.

At the late Meeting of the British Association, I gave a general resume of the subject; and in the recently published work, 'Student's Elements of Geology,' Sir C. Lyell has referred to the beds and figured one of their most characteristic fossils.

III. Sections in the Isle of Purbeck.

At the northern part of Swanage Bay, and immediately below the great chalk ridge of Ballard Down, is a little recess in the cliffs called Punfield Cove (fig 1)*. It is at this point that we find the most interesting exposure of the strata which I propose to describe. Regarding this, therefore, as a typical section, and deriving the name of the formation from the locality, I proceed in the first instance to give a detailed account of the succession of beds at this point.

1. Punfield Cove. The strata seen here, in descending order (the whole being nearly vertical), are : — (1) Upper Chalk with Flints. (2) Lower Chalk without Flints. (3) Chalk Marl. (4) Upper Greensand, with a poor representative of the Gault Clay towards its lower part, the whole being about 100 feet thick. (5) A representative of the " Lower Greensand," consisting of grey clays alternating with ferruginous sandy beds, generally destitute of fossils, but yielding Exogyra sinuata, Sow., and Panopoea neocomiensis, d'Orb. The formation is not more than 60 feet thick, and thus exhibits a great diminution from its equivalent in the Isle of Wight. This result is partly due to thinning out, and partly to overlap.

Immediately below we find the series of fluvio-marine beds, which I propose to include in the Punfield formation (see vertical sections, fig. 2) : — A. Dark blue, finely laminated shales, in part cypridiferous, with thin bands of limestone made up of Cyrena, Ostrea, &c, and fibrous carbonate of lime ( " beef" or " bacon " ), like that of the Purbecks. According to Mr. Godwin-Austen these beds are only a few feet thick. At the present time they are completely hidden by the debris from the beds above, and I have never yet had an opportunity of seeing them in situ. They appear, however, to resemble in


 * See also Sir Henry Englefield's 'Isle of Wight ' (1816), plate 29, no. 1.