INTRODUCTION. XV 
raised beaches are “ possibly of the same age as some of the 
valley gravels into which they may have merged.” 
The following species have been recorded from them : 
Mytilus edulis, Linné. 
Ostrea edulis, Linné. 
Macoma balthica, Linné (= Tellina balthica, Linné). 
Cardium edule, Linné. 
Littorina littorea, Linné. 
Buccinum undatum, Linné. 
Old beaches have been traced on the Lias and Red Marl in 
Diagram of a Raised Beach, etc., at Birnbeck Cove, 
Weston-super-Mare (after Day). 
1. ‘‘Head.” 2. Ancient Cliff. 3. Ancient Dunes. 4. Ancient Beach. 
5. Ancient Shore. 6. Present Beach. 
AA. Carboniferous Limestone. HWL. High-water Level. 
many parts of the moorlands, in places inland and about the 
present sea level. They are known as the Burtle Beds, being 
so named by De la Beche because they were at one time well 
shown at Burtle near Glastonbury. They may be traced 
along many parts of the border of King’s Sedgemoor, Sutton 
Mallet, Weston Zoyland, Chedzoy, and Middlezoy, in the 
last they are sometimes dug by the roadside. These beaches are 
composed of sand with occasional pebbles (sometimes cemented 
into hard bands) and recent marine shells. ‘ Whether these 
