1916.] THE DEPOSITS. 373 



In judging of this we have to allow for the erosion (see 

 Photo No. 12) which has taken place since. 



This must he considerable, for the tides of the latest 

 recent times must have swept away a vast amount of material. 

 Even allowing for the higher sea-level, I still think that the 

 bergs and ground ice would have failed in passing over the 

 neck of land that joined Herm to Guernsey. It was not so 

 with Jethou, for deep water existed along the line of the 

 Ferriers from Pleistocene times. After some study of this 

 problem I have come to the opinion that before the 25 feet beach, 

 or any Pleistocene deposit was laid, a river, of small size it 

 is true, started from the high land of St. Martin's (very much 

 higher than now), took the drainage of the Hubits, Mount 

 Row, Mount Durand and Montville (the George Road side of 

 the divide being taken by a small tributary through Havelet, 

 reaching the main stream at about the position of the wet 

 dock opening), passed down a sharp V-shaped valley between 

 the hills on either side of the Charroterie around the base of 

 the hills out of which parts of the Market and Arcades have 

 been cut. An old water margin is marked by a patch of 25 

 feet beach under the High Street end of the Arcade. The 

 stream then ran over part of the site of the Church and 

 rambled through the rocks wdiich out-cropped in the then 

 roadstead, passing the end of the White Hock arm, then 

 stretching across to the tower and turning to the South 

 passed between the Ferriers and the Bank. The passage 

 between the Bank and the East cliffs was probably the result 

 of the movement of the ice along the coast, but w T as begun by 

 the water draining down the Fermain valleys. The river 

 (w 7 hich for the sake of clearness I shall name the St. Peter's 

 River) East of the Bank was joined by that of the inner 

 passage, and together they fell into a deeper one, passing 

 North of Jersey on a westerly course. This I have always 

 spoken of as " La Deroute " (Mr. Sinel also describes a river 

 following practically the same course, but he places its origin 

 in more recent times). These rivers w 7 ere carved out originally 

 in late Pliocene times, but the land drainage resulting 

 from the glacial conditions, being enormously greater than the 

 rainfalls of milder conditions, deepened the course, and these 

 holding the floating ice rendered the pressure greater on 

 Jethou than on Herm. 



Assuming then, that at the commencement of the pre- 

 Mousterian submergence the sea around the island was covered 

 with ice, and that ice was jammed and exerted pressure on our 

 cliffs, we can account for the forcible removal of the sea-worn 



