AGASSIZ: THE GKEAT BARRIER REEF OF AUSTRALIA. 101 



The outer edge of this portion of the reef is formed by a series of linear 

 or curved reefs of but little width, separated by deep and narrow chan- 

 nels, against which thunders the incessant Pacific swell. The inner edge 

 of this line of reef patches is separated from the irregularly shaped reef 

 patches which constitute the width of the reef by deep tongues of 

 water, forming a more or less irregular deep continuous navigable 

 channel of from ten to twenty fathoms, or even more, and of very vari- 

 able width. Off Cape Bedford to the north of Lark Reef the reef 

 patches become more distant and distinct, and as far north as Direction 

 Island they are often widely separated. The reef fiats of the inner part 

 of the reef between Lark Reef and Aitch (h) Reef especially are widely 

 separated, leaving an almost uninterrupted passage from Lark Reef to 

 Lark Passage on the south, and similar passages to the north leading to 

 the interior channel immediately to the eastward of the cluster of reef 

 patches lying east of Aitch Reef and the Lizards and the narrow outer 

 line of disconnected exterior reef patches extending from Lark Opening 

 to One-and-Half-Mile Opening. 



This outer interior channel north of Lark Opening varies in depth 

 from ten to fifteen fathoms. East of North Direction Island it opens 

 out into a broad bay from ten to twelve miles wide, reaching round the 

 Lizards to north of the Turtle Islands, the narrow line of linear reefs 

 forming its eastern boundary. North of One-and-Half-Mile Opening the 

 reef patches within the outer line of reefs again constitute a belt varying 

 from ten to twelve miles in width. We did not extend our examination 

 beyond the line of the Lizard Islands and Eagle and Em (m) Reefs. 

 Both these reefs are within the ten fathom line. 



South of Cape Flattery (Plates XXXIIL, XXXIV.) the Low-wooded 

 Isle, Three Isles, and Two Isles are the only remnants of the numerous 

 but somewhat widely separated islands which once existed between that 

 cape and the outer edge of the Barrier Reef, the others having been eroded 

 and changed to the reef flats and patches now existing to the eastward of 

 these islands. Going north we come upon the Rocky Islets, South and 

 North Direction Islands, and the Lizard group, the last of which occupies 

 a considerable area and rises to a height of nearly 1,200 feet. The 

 windward faces of all these islands and the flats surrounding them are 

 flanked by coral, growing on their slopes and rising from a depth of from 

 seven to ten fathoms. 



To the north of the Lizards the outer edge of the Barrier Reef trends 

 more to the westward, running parallel to the coast of the mainland to 

 off Cape Melville, where it is not more than twelve miles from the coast, 



