GREAT BARRIER REEF: Matthew Flinders & the Coastal Landforms of SE Australia

Flying over the Great Barrier Reef, east of the Queensland coastline, numerous coral reefs, cays and islands can readily be seen (at least in daytime). Today, boats and ships make use of sophistocated navigational equipment to make their ways through the maze of channels. In spite of this, a ship can still run aground or be damaged by a reef if it strays from its designated course. It is not difficult to imagine the damage that a coral reef would inflict upon a timber sailing ship! Over time coral dies, but it can remain as huge masses, growing larger from the outside. It is possible for coral to eventually become consolidated, turning into rock. As it is primarily composed of lime (i.e. calcite), the rock is called limestone.	Photo 1: Coral reef features, Great Barrier Reef
Coral itself is a hard substance composed of countless skeletons of the small animal that produces these skeletons, the coral polyp. When coral polyps die, new ones colonise the available space. Thus coral formations can become larger, even eventually forming islands when sand builds up on top of shallow formations. The Great Barrier Reef as we know it is relatively recent in geological terms. During glacial events over much of the past million years the sea level was significantly lower. The areas presently under active coral cover were then dry; exposed as limestone hills with grass and tree cover. People lived in these areas during part of the most recent time of low sea level. After the Recent sea level rise, the flooded areas were re-colonised by a wide variety of corals and tropical reef animals. The reef area is now regarded as possessing a high level of biodiversity.	Photo 2: Underwater corals, Green Island, Great Barrier Reef
Reef Observations Matthew Flinders, while on expedition, was interested in observing and recording most of the new things encountered around him. He studied the corals of the reef, and offered a description that suggested a keen intellect, a high level of scientific curiosity, and a learned view of nature. Flinders named the Great Barrier Reef, after having charted a portion, concluding that reefs charted by himself and those reported by others (including Captain Cook) formed parts of the one vast coral formation. He described his visit to a coral reef: ' ... In the afternoon, I went upon the reef with a party of the gentlemen; and the water being very clear round the edges, a new creation, as it was to us, but imitative to the old, was there presented to our view. We had wheat sheaves, mushrooms, stag horns, cabbage leaves, and a variety of other forms, glowing under water with vivid tints of every shade betwixt green, purple, brown, and white; equalling in beauty and excelling in grandeur the most favourable parterre of the curious florist. These were different species of coral and fungus, growing, as it were, out of the solid rock, and each had its particular form and shade of colouring ... ' - Matthew Flinders' in Terra Australis (9 Oct 1802)
The beautiful, tiny spec of land, and its surrounding reefs, known of Green Island, are a great magnet to tourists, who come to experience a tropical 'paradise', a true coral cay. Green Island is a classical coral island, low, sand-covered, reef-fringed, colonised by plants that have migrated or been brought there by birds. It is protected through its national park status. People come to swim, stroll, snorkel and scuba dive, take photographs, ride in vessels set up for coral, fish and turtle viewing, and to relax. In summer, the island can be quite hot, and sunlight of great intensity. Unprotected skins burn quickly then.	Green Island National Park Photo 3: Green Island National Park, Great Barrier Reeft
The processes of island formation and plant colonisation are most interesting. Quote from signboard: From sand to rainforest As you enter the rainforest, imagine Green Island as it once was - a pile of bare sand on to of the reef. Over time, ocean currents and birds brought the seeds of pioneer plants to the cay. As the plants grew, their roots stabilised the shifting sands. Next, hardy shrubs and small trees appeared. As plants successively colonised the island, nutrients were added to the sandy soil. This allowed a diversity of plants to grow. The result? Today's rainforest!
How do plants cross water bodies? Quote from signboard: Across the water Pandanus, Beach almond and Cardwell cabbage can be found growing on any coast in the Indo-Pacific Ocean. How do they get around? The clue is found on the beach amongst the flotsam. Here you will find their buoyant seeds, designed for floating in the ocean currents. Casuarinas are also common throughout Indo-Pacific coasts and islands. Their seeds, small spiky balls, are dispersed by the wind, blown from shore to shore. In addition to these methods of transportation, seeds can be deposited by birds, or accidentally carried by humans.	Photo 4: Educational signboard, Green Island National Park Signboard enlargement - Seeds (on beach) from left to right (above): Pandanus, Beach almond, Cardwell cabbage, Casuarina
The seascape-landscape did not always look like this. During the most recent glacial event when sea level was about 100 metres lower, most present-day islands off the Queensland coast were part of the mainland. When the sea rose, they were cut off and their populations of plants and animals isolated. They are, therefore, much older than coral cays (such as Green Island), being colonised at the same time as the present mainland, and sharing similar geological origins with areas of the mainland.	Photo 5: Fitzroy Island, from Green Island
The nearby signboard reminds us of the following: The reefs, islands and coastal mainland are part of the sea country of the local Aboriginal traditional custodians.
FLINDERS THEME (Continued): Shipwreck! In August 1803, while returning to England from Australia, Matthew Flinders again sailed waters east of Queensland, becoming shipwrecked when the Porpoise (and another ship travelling with it) hit a reef, appropriately named Wreck Reef by Flinders. All but three of the sailors survived, but the crews of the two ships were stranded on the small reef. To save the crews, Flinders and thirteen others rowed back to Sydney in the ship's cutter; this boat was given the name Hope. On arrival in Sydney, with Governor King's assistance, they organised three ships, led by Flinders in the Cumberland, to carry out the rescue. This took place successfully six weeks later, and the 80 sailors who had remained behind were saved. Matthew Flinders' account follows, on his return to Wreck Reef: ' ... It was six weeks on this day that I had quitted the reef in the boat, for the purpose of seeking the means to relieve my officers and people ... The Porpoise had not yet gone to pieces; but was still lying on her beam ends, high up on the reef, a frail but impressive monument of our misfortune. In the afternoon I anchored under the lee of the bank, in 18 fathoms coral sand, and a salute of eleven guns from it was immediately fired, the carronades of the Porpoise having been transported from the wreck. On landing, I was greeted with three hearty cheers, and the utmost joy by my officers and people; and the pleasure of rejoining my companions so amply provided with the means of relieving their distress, made this one of the happiest moments of my life.' One of the marooned sailors, while testing a new boat that had been made while waiting for rescue, had noticed something on the horizon: 'The Rolla's top-gallant sail ... was taken for a bird; but regarding it more steadfastly, he started up and exclaimed, "D-n my bl-d what's that!" It was soon recognised to be a sail, and caused a general acclamation of joy.' Flinders was a hero to all, although his younger brother Samuel was initially able to contain his excitement at the sighting the rescue ships! 'Lieutenant [Samuel] Flinders, then commanding officer on the bank, was in his tent calculating some lunar distances, when one of the young gentlemen ran to him, calling, "Sir, Sir! A ship and two schooners in sight!" After a little consideration, Mr [Samuel] Flinders said he supposed it was his brother come back, and asked if the vessels were near. He was answered, not yet; upon which he desired to be informed when they should reach the anchorage, and very calmly resumed his calculations: such are the varied effects produced by the same circumstance upon different minds. When the desired report was made, he ordered the salute to be fired, and took part in the general satisfaction ... ' - Matthew Flinders' in Terra Australis (7 Oct 1803) After the rescue, Flinders then went on in the Cumberland, around the Great Barrier Reef to Torres Strait, and headed west with the intention of returning to England. However, the Cumberland was not up to safely completing the voyage, and tragedy eventually resulted for Matthew Flinders ... (that is another story)