13 



this grass continues to grow and bonds the dike and prevents 

 its destruction by storms. 



The dikes shown so far in these illustrations have been con- 

 structed on meadows growing salt hay, and the sod has been of 

 great advantage in bonding the dike together. In the cat-tail 

 swamps the dikes are formed of mud, which does not permit the 

 sloping sides to be as steep as those formed of sod. This 

 necessitates a greater base and a larger volume of material for 

 a given height of dike. 



I have no definite figures on the cost of these mud dikes, but 

 it is probable that they would be more expensive to construct 

 and more difficult to maintain than the sod dikes. In Bergen 

 County, near Rutherford, a mud dike was built along the west 

 bank of Berry's Creek in 191 3; this is more than two miles 

 long. The material for the dike was taken from a ditch parallel 

 to the protected side of the dike, and it was handled with an 

 orange-peel bucket operated by a land dredging machine. 



This diagram (Fig. 9) shows the operation of a tide-gate. 

 To the left is the end of a wooden sluiceway which passes under- 

 neath the dike and connects the system of meadow ditches at 

 the left end with the tidewater ditch or stream at the right end. 

 When the tide is high, the hinged gate is closed and the water 

 does not flow through the sluiceway toward the meadows. When 

 the tide is low, the pressure of the water in the ditches swings 

 the gate open and the water flows out until the tide rises to the 

 level of the ditch water, and then the gate closes again auto- 

 matically. 



Two forms of tide-gates have been used, one consisting of a 

 long, closed sluice with a hinged gate on the down-stream end, 

 and the other type being a sluiceway open at the top with a hinged 

 gate,*approximately at the middle of the sluice. 



A tide-gate of the closed sluice type is shown in the next 

 illustration (Fig. 10). This is located where the dike on the 

 south side of Bound Creek in Union County crosses a 6-foot 

 wide drainage ditch a few feet from the point where it empties 

 into Woodruff's Creek. The protected meadow area is back of 

 the dike, and the photograph is taken from the foreshore. 



