Rock art, stromatolites, and mass spawning
I. Map boundaries: 20 to 30 degrees South; 108 to 117 degrees East
II. Country (Provinces–Regions): Australia (Western Australia—Gascoyne, Mid West, Pilbara, and Wheat Belt regions).
This map area encompasses deserts and savannas of the Western Australia coastline. The northern and central areas are arid; however, occasional summer tropical storms can cause flooding as happened in December 2010 around Carnarvon. The area around Shark Bay received in excess of nine inches of rain from a tropical storm. In addition, the coastal areas from Shark Bay southward receive winter rains, which support a more savanna-like vegetation and spring wildflower displays. The southern portions of the map area, from Shark Bay southward, are dominated by eucalyptus trees in the flora, while the northern, more desertic areas, are dominated by acacia shrubs. This area was not always a desert. Until three million years ago, northwestern Australia was covered with rainforest. At this time, the Indonesian archipelago rose from the ocean floor, changing ocean currents and blocking warm water traveling south along the Australian coast. This led to the decline of precipitation in Australia, and was the death blow to rainforest vegetation (Perkins 2011).
In the northeast corner of the map, the Dampier Archipelago consists of 42 island nature reserves covered with the spinifex grass characteristic of the Pilbara shrublands. The islands and the nearby Murujuga peninsula are the site of the world’s largest known collection of rock art. Images of birds, marine life, terrestrial life including now-extinct species, and human figures are found, along with stone arrangements. These are believed to be dreaming and ceremonial sites of the Ngarda-Ngarli peoples. Continue reading