A HISTORY OF SUSSEX but it was only during the later researches of the Geological Survey, when the superficial deposits were mapped, that the relation of these to each other was clearly made out. A series of storms in the autumn and winter of 1892 combined to cut back, the cliff, scour away the beach and lay bare sections unlike any that had previously been noted. Nearly opposite Medmerry farm in Bracklesham Bay the foreshore thus bared exhibited the junction of the Glacial deposits with the Bracklesham Beds over a considerable area. The surface of the Bracklesham strata was neither smooth nor channelled, as in an ordinary shore ; but showed clear evidence of the action of floating ice, probably of ' ice-foot ' such as forms every winter in the arctic regions on the shore beneath the cliffs. The ancient foreshore, which lay only a few feet above the level of the present tidal flats, was full of basins or pits from 2 to 6 feet across. Most of these pits contained nothing but loose gravel, with a few valves of Balanus and rare fragments of marine mollusca ; the others each contained a far-transported, erratic block, which had not merely been dropped, but showed signs of having been forcibly squeezed or screwed into the clay, until its upper surface was flush with the general level. The pits filled with finer material probably mark the spots where large Fig. I. — Diagram-section to show the Relation of the Erratic Blocks to the Floor of Bracklesham Beds.' erratics were formerly deposited, though, becoming again frozen into the ice, they were lifted out and transported to fresh sites. Among the erratics found on this coast were blocks of Bembridge Limestone, large Chalk flints and Upper Greensand from the Isle of Wight ; many large masses of Bognor Rock from the ledge a few miles to the east ; and numerous more rounded blocks of harder rocks, such as peculiar granite, diorite, felsite, porphyry and hard sandstone. Most of these igneous and Palaeozoic rocks seem to have come from the Channel Islands and the Brittany coast ; one granite with large crystals of white orthoclase felspar is more probably of Cornish origin. A large block of fossiliferous Bog- nor Rock, measuring 5 feet by 4, was beautifully striated. This is 50 miles south of the nearest glacial deposits of the Thames valley, and is the only glacially striated rock yet observed south of the Thames. Large granitic boulders of character similar to those of Selsey are scat- tered over the plain as far as Worthing, where two or three are preserved in the park ; other smaller pieces occur in the raised beach of Brighton, in which deposit however they were not originally dropped. For the continuation of the Selsey record we must examine the coast nearly a mile to the south-east and nearer to the Bill, for there the series is more complete, though the glacial deposit just described has been 1 Figs. 1-4 have been reproduced, by kind permission of the Council, from the Quarterly Journal of the Geological Society. 20
