420 Reports and Proceedings — 



The raised "beach Mr. Prestwich found to abut against an old cliflf 

 that had been swamped at a later geological period by a land -wash, 

 ■which had levelled it and the old sea-land with the adjacent land- 

 surface. The mass which had thus swamped the cliff and buried 

 the beach consisted of loam and angular debris, the latter being in 

 larger proportion a,t top. In the loam he found several species of 

 land and freshwater shells and fragments of bones. The angular 

 debris consisted of pieces of the local rocks, together with a number 

 of specimens, which by their organic remains were shown to belong 

 to the Middle Purbecks, a part of the series not now existing in 

 Portland. A similar bed, but much thicker, w'as then described at 

 Chesilton, in the north of the island. It is there 60 feet thick, and 

 contains large blocks of Portland stone and Portland chert, the 

 greater number of which are in the upper part of the deposit, which 

 is here on the sea-level, and 400 feet lower than the Portland 

 escarpment which rises above it. This loam and angular debris the 

 author was disposed to attribute to a temporary submergence of the 

 land to a depth exceeding the height of Portland, and by which the 

 land as it emerged was swept, and its debris carried down to the 

 lowest levels, with the remains of its land-animals and land and 

 freshwater shells, which latter, where protected by large masses of 

 loam and suddenly entombed, have been preserved uninjured. To 

 this deposit, which is common over the raised beaches on the south 

 coast, the author proposed to apply the term " Land-wash." 



The paper concluded wdth a short notice of the drift-beds formed 

 subsequently to the denudation of the Weymouth district, and there- 

 fore never on the high-level Portland drift. Amongst these was one 

 near Weymouth of singular character, consisting almost entirely of 

 subangular fragments of Oreensand chert, which could not have 

 been derived from beds nearer than Abbotsbury. The lower drift of 

 the district is the valley-gravel of Upway and Radipole, in which 

 the remains of Eleplias primigenius have been found. 



Discussion. — The Rev. O. Fisher remarked that the summit of the Isle of Port- 

 land was capped with polished pebbles. Bones of Elephant and of Bos longifrons, 

 with a slingstone, were found on a ledge in a fissure at the top of the talus, together 

 with materials from the surface and land-shells. The polished pebbles were pro- 

 duced by water containing mud filtering through them, and passing below into 

 fissures caused by the slipping of the stone on the clay. 



Mr. Topley considered that the date of the disturbance described was low 

 down in the Drift period. A part of the drift containing Lower Greensand 

 pebbles may have been caused by an unconformable overlap. 



Prof. Hughes thought that the whole question turned upon the original configu- 

 ration of the country, — what was the line of the old channel in the old river- valley 

 now forming the English Channel? 



Prof. Ramsay remarked that many questions were raised by this paper. In the 

 anticlinal of the Weald the Cretaceous strata are accidentally conformable, whilst 

 more to the west the Oolites are unconformable to the Cretaceous. The mass of 

 the Eocene passed over the anticlinals of the Portland district ; and what had 

 become of the overlying mass ? He thought that it had probably been removed 

 by subaerial influences. 



Mr. Koch referred to the polishing of stones in river-beds, which he had 

 noticed in the north of Spain, in Bohemia, and in the Jura, and stated that in the 

 river-beds carbonate of lime is deposited on the stones and preserves their polish. 



Mr. Godwin-Austen said that to whatever period the east and west disturbances 



