BY G. H. HALLIGAN. 637 



round Stephens Point at an increased velocity and does not resume 

 its normal direction, parallel to the coast, until within a few 

 miles of Nobby's Head, the entrance to the Hunter River. 

 Nobby's Headland is not sufficiently prominent to cause a deflec- 

 tion of the current to the north, and the movement of the beach- 

 material at the entrance to Port Hunter is to the south. This 

 is abundantly evident from an examination of the sand heaped 

 against the northern breakwater now under construction, and 

 this sand will continue to pile up till the northern breakwater 

 extends far enough to the east to form the base of the Zeta curve 

 before referred to. The southern breakwater is, of course, valu- 

 able as a shelter from the south and south-east sea, but it is the 

 northern breakwater alone that will keep the entrance free from 

 drifting sand. 



Lake Macquarie and Tuggerah Lake* both have rocky head- 

 lands on the southern side of their entrances, and the moving 

 sand spit, with the characteristic Zeta curve on the north, shows 

 without doubt the direction of the alongshore current. 



The prominent headland Avith the descriptive name of Long 

 Point, with its dangerous reef running still further to the east, 

 deflects the current, and causes a strong northerly return current 

 along the beach. The effect is to force the entrance to Narrabeen 

 Lagoon to the northward till a rocky projection is met with; and 

 as the fresh water from Narrabeen Creek is inconsiderable, a sand 

 bar is formed, which completely blocks the entrance to the lagoon. 

 After heavy rains the water rises sufficiently high to burst this 

 sandy dam, and for several weeks the tide ebbs and flows in the 

 lagoon. The northerly movement of the beach-material, however, 

 soon prevails, and the entrance is once more blocked and remains 

 so until the next flood. 



The Hawkesbury, Port Jackson, Botany Bay.— The entrances 

 to the Hawkesbury River, Port Jackson and Botany Bay 



* The term Lake is here used in deference to popular nomenclature. The 

 so-called Lakes Macquarie, Tuggerah, Illawarra and several others are not 

 lakes at all, but arms of the sea. 



