Seal Island (Investigator Strait)
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  Seal | |
| Geography | |
|---|---|
| Location | Investigator Strait |
| Coordinates | 35°20′19″S 136°55′13″E / 35.33848°S 136.92017°E |
| Highest elevation | 35 m (115 ft) |
| Administration | |
Australia | |
Seal Island is an island located in Investigator Strait off the south coast of Yorke Peninsula in the Australian state of South Australia about 7 kilometres (4.3 miles) south south-west of Stenhouse Bay. Since 1972, it has been part of the Althorpe Islands Conservation Park.
Seal Island is about 7 kilometres (4.3 miles) south south-west of Stenhouse Bay. It is described as an ‘elevated hump’ rising to a height of 35 metres (115 feet) with a series of ‘segmented islets’ at its west side.[1][2] Seal Island is reported as being best accessed via its north coast and during the ‘calmest weather’.[1] A number of sources consider Seal Island along with the Althorpe Islands and Haystack Island to be a group of islands known as the Althorpe Islands Group.[1][2][3]
Formation, geology and oceanography
Seal Island was formed between 7500 and 8900 years ago after sea levels rose at the start of the Holocene thereby separating Yorke Peninsula from Kangaroo Island.[4] Seal Island is the remains of a granite inselberg capped by a layer of Bridgewater Formation calcarenite which has been extensively eroded by the action of the sea.[1][2] Seal Island rises from a depth of 20 metres (66 feet) within 300 metres (980 feet) to its west and south shores, and within 700 metres (2,300 feet) of its east shore.[5]
