Perth Canyon is a submarine canyon located on the edge of the continental shelf off the coast of Perth, Western Australia , approximately 22 kilometres (14 mi) west of Rottnest Island . It was carved by the Swan River , probably before the Tertiary , when this part of the continental shelf was above sea level. It is an average of 1.5 kilometres (5,000 ft) deep and 15 kilometres (9.3 mi) across, making it similar in dimension to the Grand Canyon .
7-423: It occupies an area of 2,900 square kilometres (1,100 sq mi) and ranges in depth from 700 to 4,000 metres (2,300 to 13,100 ft). Within a few kilometres its depth drops from 200 metres (660 ft) down to 1,000 metres (3,300 ft), and then it continues as a deep gully all the way out to the 4,000-metre (13,000 ft) depth, which is about another 30 kilometres (20 mi) farther west. It contains
14-628: A naval base at nearby Garden Island . In June 2006 the waters around the Perth Canyon were the site of an ocean vortex 200 kilometres (120 mi) in diameter and 1,000 metres (3,300 ft) deep. It was visible from space, and scientists claimed at the time that it had the potential to affect the local climate and the climate further abroad. The vortex was described by scientists as a marine "death trap", as it sucked in fish larvae. 32°01′S 114°59′E / 32.01°S 114.98°E / -32.01; 114.98 This article about
21-490: A specific oceanic location or ocean current is a stub . You can help Misplaced Pages by expanding it . This article about a location in Western Australia is a stub . You can help Misplaced Pages by expanding it . Plunge pool A plunge pool (or plunge basin or waterfall lake ) is a deep depression in a stream bed at the base of a waterfall or shut-in . It is created by the erosional forces of cascading water on
28-483: The Channeled Scablands of eastern Washington . They can also be found underwater in areas that were formerly above sea level, for example, Perth Canyon off the coast of Western Australia . Plunge pools are fluvial features of erosion which occur in the youthful stage of river development, characterized by steeper gradients and faster water flows. Where softer or fractured rock has been eroded back to
35-404: The rocks at the formation's base where the water impacts. The term may refer to the water occupying the depression, or the depression itself. Plunge pools are formed by the natural force of falling water, such as at a waterfall or cascade; they also result from man-made structures such as some spillway designs. Plunge pools are often very deep, generally related to the height of the fall,
42-399: The volume of water, the resistance of the rock below the pool and other factors. The impacting and swirling water, sometimes carrying rocks within it, abrades the riverbed into a basin, which often features rough and irregular sides. Plunge pools can remain long after the waterfall has ceased flow or the stream has been diverted. Several examples of former plunge pools exist at Dry Falls in
49-510: The world's largest plunge pool —a depression in the canyon that is 2 kilometres (1.2 mi) long, 6 kilometres (3.7 mi) across, and 300 metres (980 ft) deep. The canyon is considered "a perfect spot" for deep sea fishing. The Perth Canyon is a feeding ground for pygmy blue whales , especially at the rims of the abyss. It is also a training ground for the Royal Australian Navy Submarine Service , stationed at
#709290