AGASSIZ: THE GREAT BARRIER REEF OF AUSTRALIA. 97 



separating the islands vary from eighteen to thirty fathoms. Lady 

 Elliot Islet rises from water a few fathoms deeper, while the islands of 

 the Capricorn group which run in a southerly direction come up from a 

 depth of ten to twenty fathoms. To the north of Keppel Bay, the 

 Keppel Islands are less than seven miles from the coast, and are 

 connected with it by extensive shoal patches. 



Shoalwater Bay (Plate XXVI.) is flanked on the east by the Penin- 

 sula Range Point, the summits of which rise to over 1,700 feet, and by 

 Townshend and Leicester Islands and the Cannibal group. The extension 

 of the Normandy range (over 2,500 feet in height), separating Shoalwater 

 Bay and Broad Sound, forms an extensive peninsula to the east of Broad 

 Sound, the extremity of which is formed by numerous islands and flats, 

 while on the west side of the main channel leading to Broad Sound the 

 Flat Islands, with their shallows and flats, project from the mainland 

 across a part of its northern opening. 



North of Broad Sound Channel, over an area nearly sixty miles wide 

 by a somewhat greater length in a northerly direction extend irregularly 

 scattered islands, some of theuuof considerable size and height (Plate 

 XXIX.), the Guard Fish cluster, the Northumberland Islands (over 700 

 feet), the Percy Islands (over 800 feet). The southern islands rise from 

 an extreme depth of thirty fathoms, while the northern ones are within 

 the ten fathom line ; they are all rocky and of the same geological 

 structure as the adjoining mainland. 



Separated from the outermost of these islands by a wide channel, with 

 a depth of from thirty to forty-five fathoms, we come, at a distance of 

 about forty miles, upon the inner edge of the Great Barrier Beef, the 

 northern extension of Swain Reefs, the southernmost outlines and the 

 inner and outer edges of which alone have been sketched on the hydro- 

 graphic charts. The depth off the eastern face varies from twenty fathoms 

 close to the reef to thirty-five at a distance of from one and a half to two 

 miles seaward. 



The greatest width of the disconnected patches known as Swain Reefs 

 is nearly seventy miles, and they extend in a northwesterly direction 

 nearly unbroken for more than 150 miles. Swain Reefs are known from 

 the description which Jukes gives of sailing through their labyrinth of 

 broad and deep channels. Whitsunday Passage is a comparatively 

 deep channel from fourteen to twenty-four fathoms, separating the 

 mainland and the small islands close to it from the northern extremity 

 of an extensive chain of islands, the Cumberland Islands (Plate XXX.), 

 reaching from Hayman Island on the north to Penrith and the adjoin- 



