THE OYSTER. 79 



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 

 surface, until in the lower part of North Carolina there 

 is on each side of the channel a wide strip of hard 

 bottom, which is bare at low^ tide and covered with 

 oysters up to high-water mark, although the oysters 

 are most abundant and largest at the edge of the deep 

 water, where they form a well-defined reef In our 

 own waters there is usually a strip along the shore 

 where no oysters are found, as the depth of water is 

 not great enough to protect them in wn'nter. The 

 whole of the hard belt is not uniformly covered with 

 oysters, but it is divided up into separate oyster rocks, 

 between which comparatively few can be found. 



The boundaries of a natural rock which has not been 

 changed by dredging are usually well defined, and 

 few oysters are to be found beyond its limits. The 

 oysters are crowded together so closely that they can- 

 not lie flat, but grow vertically upwards, side by side. 



