272 JOSEPH PEESTWlCHj F.ll.S., ¥.Q.S., ON A POSSIBLE 



at Sangatte, near Calais, Avhich is identical ^-ith the section 

 at Brigliton, the old Beach in the estuary of the Somme, and 

 the traces of " HeacV on the coasts of Normandy, we come 

 to the novel and very illustrative case furnished by the Channel 

 Islands. Both Guernsey and Jersey consist in greater part 

 of a table-land of granitic and metamorphic rocks 300 to 

 400 feet high, more or less covered by a deposit, 5 to 20 feet 

 thick, of loam or Loess, and terminating in high cliffs. At the 

 foot of these are occasional remnants of an old Raised Beach. 

 (5 to 20 feet above the present beach, surmounted by a slop- 

 hig "//i"rt(Z " composed of rock fragments and loam carried 

 down from the hills inland. It is certain that it is not a mere 

 talus, for the rubble has a base of loam identical with that on 

 the central plateau, and the delnns has often been propelled 

 to considerable distance outwards from the foot of the cliffs. 



The plateau loam or Loess deserves special attention, for, 

 as there are no rivers to have originated flood waters, this 

 Loess cannot have had a fluviatile origin ; nor, as there is no 

 higher ground, could it be the result of rain-wash ; neither 

 can it be the result of the disintegration of the surface rocks.* 

 It must therefore have had an origin different from that 

 usually ascribed to the Loess, and this I would attribute to 

 the deposition of sediment from the turbid sea- waters during 

 submergence, whilst the ^' head" results from the surface 

 debris, together with portions of this loamy sediment, swept 

 off by divergent currents in quaquaversal directions during 

 upheaval. Considering the then isolation of these islands, no 

 other explanation seems to me possible to account for the 

 presence of Loess in such a position. The cause must have 

 been continental, not insular. 



The High-level Loess of France and Central Europe. — A 

 great portion of the Loess of Europe is no doubt of fluviatile 

 origin, and is confined to river valleys. But there is a still 

 larger portion, to which such an origin cannot be ascribed, 

 for this latter is not confined to the river valleys, but is 

 found on the dividing watersheds and on the high plains 

 separating the river basins. In the North of France it at- 

 tains a height of 400 to (300 feet, and in the neighbourhood 



* No land shells have been found in this Joam in either Jersey or 

 Guernsey, but they have been found in a similar deposit in the island of 

 Brehat on tlie coast of Brittanv. 



