THE MOUNT DESERT REGION 37 



the extreme soiithwebtern shore of the Island in the vicinity 

 of Ship Harbor, and along a stretch of reef between South- 

 west Harbor and the southwestern shore of the Island. 



The character of the rocks plays a very large part in the 

 formation of the tide pools, for while the granite is formed 

 into them by wave action the sedimentary rock, flaggy slate 

 and shale, through the action of the waves and frost splits off 

 and prevents their formation. 



Unlike the region further south, the collecting along the 

 shore of the estuaries discloses some of them to be almost 

 barren of forms on account of the large amount of clay silt 

 that is washed down and the absence of sandy beaches. This 

 is also true of many of the fiats where the mud has covered the 

 original stones and sand that indications show must have 

 been what they were before they became covered with a thick 

 layer of mud. 



The shores of the Region, of course, are constantly chang- 

 ing, and this is particularly true of the flats and beaches in the 

 inner Bay and the upper part of the Western Bay. The 

 change is noticeable even in the 12 years that I have been 

 watching them, and as an example of this the taking of 

 Venus mercenaria is interesting. 



In looking over some old maps of Mount Desert Island in 

 1921 1 noticed the name Quahog Bay given to one of the places 

 on the west side of the Island and, thinking that it might 

 have acquired the name from the fact that quahogs were found 

 there, I searched but did not find any nor did I find them in 

 any of the coves up the west side of the Island until I reached 

 the most northwesterly one at a place called Clark's Cove, 

 where I took one in 1927. In the field work of the Survey 

 we took another in August, 1928, a very large one (125 mm.), 

 and later I took a pair of dead valves. The records show that 

 part of this Cove was at one time called Sand Beach and on 

 digging down one finds that there has been a sand beach which 

 has gradually become silted over wdth mud. This probably 

 accounts for the fact that only large individuals were found 

 and no indication of young. 



