112 THE GREAT BARRIER REEF. 



Tlie precipitous land of the Palm Islands group is ot granitic formation, and includes some 

 peaks of considerable height. The Great Palm Island is over i,8oo feet high; Orpheus Island, 

 568 feet; and Pelorns Island, 924 feet. The coastal island of Hinchinbrook, within clear view, and 

 lying some ten miles only to the north-west of the Palm Islands, attains, in accordance with 

 the Admiralty charts, to an elevation of no less than 3,650 feet. As originally defined by Mr. 

 Jukes, it is made up of broken masses of hills, covered with rugged knolls and sharp, inacessible 

 pinnacles, and furrowed by deep and precipitous gullies and ravines. There are two minor 

 navigable entrances (Palm and Magnetic Passages) through the Great Barrier, opposite the Palm 

 Island and the Hinchinbrook groups. Although fifty miles from the mainland, they are 

 significantly parallel with the estuary of the Herbert River, which drains the watershed next in 

 order, northwards, to that of the conjoint Mackenzie, Dawson, and Fitzroy basin. 



No feature of special interest is associated with the reefs intersected by the navigable 

 course for the next seventy miles, northwards, from Hinchinbrook, all the reefs and shoals being 

 of the uniform coral lormation as those previously referred to. At about the point indicated, 

 three openings occur in relatively close proximity; and the edge of the Barrier, at the same point, 

 approaches to within thirty miles of the mainland coast. The reef passages referred to are, in 

 their consecutive order from the south, the Flora Pass, the Grafton Passage, and the. Trinity 

 Opening. All three are contained within the narrow limits of less than forty miles, and probably 

 represent the delta-like subdivision ot a primarily single channel. The soundings immediately 

 outside the Trinity Opening, more particularly, are deeper than those at any point so far 

 passed. From Break-.sea Spit up to the gaps now under notice, soundings taken off the 

 immediate edge of the Barrier, as recorded in the Admiralty charts, fluctuate between one 

 hundred and two hundred fathoms, with the exception of a single one of 365 fathoms, a little to 

 the south of the Flora Pass, and opposite the estuary of the Johnstone River. Close against the 

 outer edge of the Barrier at the Trinity Opening, as great a depth as 650 fathoms is recorded, 

 with several in the near vicinity of over 250. On referring to the land chart, to ascertain whether 

 in this case also any river estuary, by coincidence or otherwise, harmonises in its bearings 

 with this Barrier gap, it will be found that the Barron River discharges its waters in such 

 position, a little to the north of Cairns. This river is remarkable for its rugged, precipitous 

 course and mighty waterfalls in the back country, one of which is seven hundred feet high. 

 During the tropical flood seasons, the Barron River brings down a deluge of water that would 

 materially affect the coral life of a reef lying across its track at a less distance than the 

 present Barrier opening. 



The reefs northwards of the Trinity Opening are much more continuous, or wall-like, along 

 the Barrier's outer periphery than to the south of that passage. The interior reefs also are much 

 more extensive, and constitute, in this respect, favourable collecting grounds for prosecutors 

 of the Beche-de-mer fishing industry. Green Island, some ten or twelve miles only out to sea 



