A GUIDE 



TO THE 



GEOLOGY OF THE ISLE OF PURBECK, 



&c. &c. 



As the following pages are intended chiefly as a guide to the 

 collector of the organic remains, and the amateur student of the geology 

 of the neighbourhood of Swanage, I propose commencing with the Tertiary 

 'lays of Barton Cliff and the lacustrine beds which lie immediately 

 t)ove them at Hordwell Cliff, as they are at no great distance from and 

 >\ ithin sight of the town. 



In a paper by Mr. Searles Wood, in the first number of the London 

 Geolocjical Journaly it is stated that the upper marine formation occurs on 

 the west side of a ravine, which is situated near the village of Milford, 

 ** at an elevation of ten or twelve feet above high water mark, but with a 

 thickness of only nine or ten inches, and only traceable for about forty 

 yards." He gives a list of Testacea from this stratum containing fifty- 

 six species. At Hordwell Cliff the strata are in the order of the follow- 

 ing list, which I have compiled partly Irom that published by Mr. Lyell 

 in the Geological Transactions, and partly from my own observations. 



1. Alluvial gravel, containing large teeth similar to those which are 

 abundant in the gravel of the neighbourhood of Cambridge, and 

 probably the teeth and other remains of elephant. 



2. Fine white sand with greenish marl. 



3. Green marls, with arenaceous clays, containing bituminous wood, and 

 seed-vessels, with shells of Helix, Planorbis, &c. Stratum of 

 laminated marl with Cyprides. 



4. Sands and clays, Mya gregaria, abundant ; a layer of bituminous clay 

 containing lignite. 



5. White calcareous marl, with freshwater shells, Planorbis abundant, 

 and a large Helix, and Gyrogonites. A layer of black carbonaceous 

 clay with lignite. 



6. Green unctious and arenaceous marls. A thick bed of extremely 

 fine white sand, containing an abundance of fiuviatile shells of genera 

 Mya, Lymnaea, Melania, Cyclas, Paludina, &c. It was from this bed 

 that nearly all the fossils were obtained which are enumerated in Mr. 

 Searles Wood's list, viz : — bones and teeth of Palaeotherium, Dichobune, 

 Microchaerus, Spalacodon, Seal, Alligator, Lepidosteus, &c. 



7. Light green calcareous and sandy marls, with layers of a carbonaceous 

 clay containing lignite, abundance of shells, and seed-vessels. Here, 

 I imagine, is the bed which Mr. Searles Wood designates " Lower 



I Marine." It rises from beneath the beach a short distance to the east 

 * of Mead End, and may be traced to the top of Beacon Bunny, and 

 J on to about half way from thence to Barton, where it ends abruptly in 

 the deep yellow coloured Bagshot sands. 



