60 BEITISH MOSSES. 



the way in which the villages lie and the moor is appor- 

 tioned between them suggests that the Pouldon Hills and 

 some other spots which slightly rise above the level of the 

 Moss were the original seats of population. Originally 

 this whole area appears to have been open to the Bristol 

 Channel, of which it formed a bay or recess. The Burtle 

 beds are a marine deposit well seen at the slight elevation 

 on which the village of Burtle stands, which have been 

 traced in various places along the borders of the moor and 

 indicate the old line of beach. A curious confirmation of 

 this geological fact is afforded by the presence the one on 

 Shapwick Heath , and the other near Glastonbury of two 

 plants (the Rumex maritimus and the Vicia lutea) which 

 are shore plants, but which have until recently maintained 

 their places as remains of the ancient marine flora, show- 

 ing the retreat of the sea. The Vicia lutea has, I believe, 

 recently succumbed in this interesting locality to the 

 British collector. The description of Glastonbury as the 

 Isle of Avalon, and the account of the bringing of the 

 body of King Arthur from Tintagel to its resting-place 

 at Glastonbury, are confirmations from tradition of the 

 same fact. 



Then a change came over the district, apparently by the 

 formation of barriers of sand or mud along what is now 

 the shore of the Bristol Channel, and along the sides of 

 the overflowing rivers, and in that way the sea-water was 

 shut out, and a depressed region left with a mud surface ; 

 on this there arose a forest of oak, ash, and yew, then the 

 water stagnated, and in it the Sphagnum grew, and 

 gradually filled it up, killing the growth of trees on the 



