Thursday, June 07, 2007

Terra Australis

Terra Australis (also: Terra Australis Incognita, Latin for "the unknown land of the South") was an imaginary continent, appearing on European maps from the fifteenth to the eighteenth century. It was first introduced by Aristotle. Aristotle's ideas were later expanded by Ptolemy, a Greek cartographer from the first century AD, who believed that the Indian Ocean was enclosed on the south by land. When, during the Renaissance, Ptolemy became the main source of information for European cartographers, the land started to appear on their maps. Although voyages of discovery sometimes did reduce the area where the continent could be found, cartographers kept drawing it on their maps and scientists argued for its existence with such arguments as that there should be a large landmass in the south as a counterweight against the known landmasses in the Northern Hemisphere. Usually the land was shown as a continent around the South Pole, but much larger than the actual Antarctica, spreading far north in particular in the Pacific Ocean area. New Zealand, discovered by Abel Tasman in 1642, was by some regarded as a part of the continent as well as Africa and Australia.
Based on Wikipedia

Saturday, September 30, 2006

The Great Barrier Reef

The Great Barrier Reef is the world's largest coral reef. The reef is located in the Coral Sea, off the coast of Queensland in north-east Australia. It stretches over 2000 kilometres in length and can be seen from space.

The Great Barrier Reef is a large system of about 900 islands and over 3000 coral reefs, which mostly lie some distance from the mainland coastline. Due to its vast biodiversity, warm clear waters and its accessibility from the floating guest facilities called 'live aboards', the reef is a very popular destination for tourists, especially scuba divers. Many cities along the Queensland coast offer boat trips to the reef on a daily basis. Several continental islands have been turned into resorts.

The Great Barrier Reef is sometimes referred to as the single largest organism in the world. In reality it is made up of many millions of tiny organisms, as are all coral formations. Some people believe that the most significant threat to the future of the Great Barrier Reef in its current form and of the planet's other tropical reef ecosystems is global warming. Many of the corals of the Great Barrier Reef are currently living at the upper edge of their temperature tolerance, as demonstrated in the coral bleaching events of the summers of 1998 and 2002. As was seen at those times, under the stress of waters that remain too warm for too long, corals expel their photosynthesising zooxanthellae and turn colourless, revealing their white calcium carbonate skeletons, and if the water does not cool within about a month the coral will unfortunately die. Australia has just experienced its warmest year on record and abnormally high sea temperatures during summer (2006) have caused massive coral bleaching in the Keppel island group.

Global warming has triggered the collapse of reef ecosystems throughout the tropics. Increased global temperatures bring more violent tropical storms, but reef systems are naturally resilient and recover from storm battering. While some believe that an upward trend in temperature will cause much more coral bleaching, others point to data that demonstrates that the global temperature has never changed by more than a degree for a very long time.

Sunday, March 26, 2006

The Twelve Apostles

The Twelve Apostles in Victoria are a collection of natural limestone stacks standing off shore in the Port Campbell National Park, on the Great Ocean Road in Victoria, Australia. Their close proximity to one another has made the site a popular tourist attraction. Originally the site was called the Sow and Piglets. The name was changed in the 1950s to the more majestic "The Twelve Apostles" to lure more visitors, even though there were only nine stacks.

The stacks have been formed by erosion, and are varying heights and thicknesses. A number have fallen over entirely as their bases are being continually eroded by the force of the waves. A 50-metre tall Apostle collapsed on July 3, 2005, leaving eight. The previous well known feature in Port Campbell National Park to succumb to erosion was the 'London Bridge.' Two visitors were trapped when a natural arch collapsed - the people were rescued by helicopter a few hours later. The island of rock has since been called 'London Arch.'The rate of erosion at the base of the limestone pillars is approximately 2 cm per year.
Based on Wikipedia