onto what had been the beach around 100–150 years before. Kenneth McIntyre hypothesised they were dropped in 1522 by Mendonça or one of his sailors. Since the keys have been lost, however, their origin cannot be verified. A more likely explanation is that the "much decayed" keys were dropped by one of the limeburners shortly before being found, as the layer of dirt and shells they were found below was dated as around 2300–2800 years old, making La Trobe's dating implausible. According to geologist Edmund Gill, and engineer and historian Peter Alsop, the error by La Trobe is quite understandable, given that in 1847 most Europeans thought the world was only 6000 years old. Cannon In 1916, two bronze cannon were found on a small island in Napier Broome Bay, on the Kimberly coast of Western Australia. Since the guns were erroneously thought to be carronades, the small island was named Carronade Island. Kenneth McIntyre believed the cannons gave weight to the theory of Portuguese discovery of Australia. However, scientists at the Western Australian Museum in Fremantle made a detailed analysis of the weapons, and determined that they are swivel guns, and almost certainly of late 18th-century Makassan, rather than European, origin. The claim that one of the guns displays a Portuguese "coat of arms" is incorrect. In January 2012, a swivel gun found two years before at Dundee Beach near Darwin was widely reported by web news sources and the Australian press to be of Portuguese origin. However, later analysis by the Museum and Art Gallery of the Northern Territory indicated it was also of Southeast Asian origin. Further analysis suggests that the lead in the gun most closely resembles that from Andalusia in Spain, although it may have been recycled in Indonesia. The museum holds seven guns of Southeast Asian manufacture in its collection. Another swivel gun of Southeast Asian manufacture, found in Darwin in 1908, is held by the Museum of South Australia. In 2014, it was revealed that sand inside the Dundee beach gun was dated to 1750. Bittangabee Bay Kenneth McIntyre first suggested in 1977 that the stone ruins at Bittangabee Bay, in Beowa National Park near Eden on the south coast of New South Wales, were of Portuguese origin. The ruins are the foundations of a building, surrounded by stone rubble that McIntyre argued may have once formed a defensive wall. McIntyre also identified