400 THE NEOLITHIC PERIOD. 



destroyed. The sea rise continued and the present level was 

 passed and a subsidence, very moderate in extent, followed. 



Let me now dwell on the evidences of this subsidence, for 

 as it is an event near our own days it has an added interest. 



Years ago I detected and registered the fact that there 

 were deposits of a later date than those caused by the forest 

 subsidence. These consisted of marine sands chiefly, although 

 a few deposits of blue clay seemed to fall into line with them. 

 I followed them and found that the line of the margin 

 was one about 10 to 12 feet above anything that could be 

 attributed to the present sea level. But knowing that such a 

 thing as extraordinary high tides could occur, and that our 

 storm beaches were in fact some feet above the newly detected 

 sands, I felt that caution had to be exercised. Then the 

 dolmen at L' Islet was discovered. It rested on the 25 foot 

 beach. As soon as I saw that the dolmen had been emptied and 

 refilled with a washed-in and layered deposit of sand and clay 

 derived from the very mound on which it rested, I knew what 

 had happened. The Braye du Valle, I saw plainly, when 

 deeper than the present level made it by some 12 feet, would 

 have contained sufficient water depth to have given confused 

 waves under the action of storms to have reached the dol- 

 men and to have emptied it, and to have redistributed the 

 sands of the hougue and to have refilled it or permitted it to 

 be refilled by rain wash. 



The supposed rise fitted in with the marine sands on 

 the low lands. I nevertheless needed assurance that 

 I was right and took two or three of our members to 

 positions where these sands rested, but I doubt if these visits 

 were quite convincing, so I then sought for evidence of other 

 observers. I came on a paper by Godwin-Austen, which I 

 had used in reference to changes of level on the English side 

 of the channel when lecturing on the earlier submergences, 

 but owing no doubt to preoccupation when consulting the 

 paper I failed to attach importance to his statement of a 

 subsidence in late times. More than this, our author had 

 actually noted the very facts I had been so diffident about 

 when visiting the island. 



Godwin-Austin says : " In St. Sampson's parish, Guernsey, 

 the upper surface of the granite is covered by a considerable 

 thickness of granitic sand containing large angular fragments 

 of granite (our frost-riven detached blocks), above this is a 

 pure sea sand and pebbles." If I had read this with my mind 

 on the look out for other facts, I certainly missed its reference 

 to the problem presented by the marine elevated sands and the 



