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 them of 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 Reef, 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- 
