292 THE STRUCTURE AND SUCCESSION AT 



Here, then, was formerly a lake, surrounded by gently 

 sloping glacial debris, which itself lies for the most part as a 

 thin mantle upon the bedrock. It was of irregular outline, 

 with at least three coves on three of its sides. These now reach 

 to the shore line, and the sea occupies what was once their ends. 

 The three coves are represented by (1) the sections exposed 

 on the shore between Black point and Cranberry Head; (2) 

 the shore of Big pond; and (3), the deepest, at Lloyd's cove, 

 to which the sea at times has access. 



An additional ten or fifteen feet would have admitted the 

 sea to the whole of this lake basin. In that event, Cranberry 

 Head and Black point would stand out as islands. 



kihoreline phenomena. — According to the classitication of 

 Dr. F. P. Gulliver, the shore as a whole is in an adolescent 

 stage of development, following depression. Proof of this 

 depression hardly need be stated in detail — the presence of 

 estuaries like Sydney harbor itself may be accepted as sufficient 

 evidence. It may be said, parenthetically, that no positive data 

 have been gathered showing- recent elevation here. 



The adolescence is shown by the forelands of Allen point 

 and Jackson point, by South bar on the S^^dney side of the 

 harbor, by bay bars at Llo^^d's cove and Big pond, and by shore 

 swamps near Limestone creek. Finally, the rapid wearing away 

 of the cliffs shows that maturity has not been reached. Indeed, 

 the mouth of the harbor is still in a somewhat earlier stage in 

 its cycle than the shore nearer the head of the estuary. 



Glaciation. — The whole of the field has been glaciated, and 

 the topography reflects in a general way a pre-glacial relief, 

 subdued by fillimig up hollows and planing down eminences. 

 The general evenness of resistance is shown by the scarcity of 

 inland outcrops. 



Striations are rare, because of the post-glacial weathering 

 of the surface wherever unprotected by soil. At upper ^orth 



