THE OYSTER. 83 



once if it were to fall on such a bottom, and in order 

 to have the least chance of survival it must find some 

 solid substance upon which to fasten itself, to preserve 

 it from sinking in the soft mud, or from being buried 

 under it as it shifts with wind and tide. In the de- 

 posits which form the soft bottom of sounds and 

 estuaries solid bodies of any sort rarely occur, and the 

 so-called " rocks " of the Chesapeake are not ledges or 

 reefs, but accumulations of oyster shells. 



Examination of a Coast Survey chart of any part of 

 the Chesapeake Bay or of any of its tributaries will 

 show that there is usually a mid-channel, or line of 

 deep water, where the bottom is generally soft and 

 where no oysters are met with, and on each side of 

 this an area where the bottom is hard, running from 

 the edge of the channel to the shore. This hard strip 

 is the oyster area. It varies in width from a few yards 

 to several miles, and the depth of water varies upon it 

 from a few feet to five or six fathoms, or even more. 

 But there is usually a sudden fall at the edge of the 

 channel, where the oysters stop, and we pass to soft 

 bottom. The oyster bottom is pretty continuous, ex- 

 cept opposite the mouth of a tributary, where it is cut 

 across by a deep, muddy channel. The solid oyster- 

 rocks are usually situated along the outer edge of this 

 plateau, although in many cases they are found over 

 its whole width nearly up to low-tide mark, or beyond. 

 As we pass south along the bays and sounds of Vir- 

 ginia and North Carolina, we find that the hard 

 borders of the channel come nearer and nearer to the 



