HYDROGRAPHY OF THE MARINE WATERS 49 



northeast and southwest. Upon the change of the wind to the northward, 

 however, an immediate and comparatively violent movement of the water 

 will take place in the direction of the inlets where the level has already been 

 reduced, and though this movement is rapid, amounting sometimes to two 

 knots per hour, yet considerable time is necessary to displace the salt water 

 by the fresh, and consequently high densities may easily be found with north- 

 westerly winds and southerly currents, and, vice versa, low densities with 

 easterly and southerly winds and northerly currents. In the southern part of 

 the Sound the rule will be modified somewhat owing to the trend of the land 

 and lay of the shoals, the greater densities being found, as before, after 

 easterly winds, but a southerly wind immediately effecting a diminution of 

 gravity. 



'Trom a careful inspection of the determinations of specific gravity and 

 observations of winds and currents, the following are deduced: 



"Easterly winds will cause high water and high densities. 



"Westerly winds will cause low water and low densities. 



"Southerly winds will cause low water and low densities in the southern 

 part of Pamplico Sound and high densities in the northern part. 



"Northerly winds will have an exactly opposite effect in each locality. 



"The greatest density and the highest water will be coincident. 



"The greatest density and the highest water will be found, after continued 

 easterly weather — 



"In the northern part of the Sound immediately before the shift of wind 

 to theN. W.; 



"In the southern part of the Sound immediately before the shift of the 

 wind to the S. W. 



"The strongest currents will be found immediately after a shift of wind. 



"The weakest currents will be found immediately before a shift of wind." 



Generalizations on the remaining sounds are difficult because they are so 

 numerous, small, and varied. All generally extend with their long axes par- 

 alleling the coastline and in general they are well supplied with inlets; so 

 salinities are usually high. Figure 2 1 for Beaufort is representative of condi- 

 tions near an inlet. With respect to Core Sound, Winslow (1889) offers the 

 following interpretation from his accumulated records: "Anomalous as it 

 may seem, in Core Sound, its general direction being N. E. and S. W., a 

 northeast gale will cause high water and high densities and a southwest gale 

 the reverse — showing that the real outlet of that Sound is into Pamlico and 

 not Beaufort Inlet as would be supposed." Inlet changes are such that this 

 situation may have been altered since that time. 



High productivity characteristic of coastal waters such as these North 

 Carolina sounds is commonly attributed to the extra nutrients added by 

 river discharge. Theoretically this discharge, operative since the seas first 



