17°S 140°E Sweers Island – Queensland by Degrees

THE POINT
 

17°S 140°E confluence, Google Earth

Location: This confluence point is located in the waters of the Gulf of Carpentaria 40 km east of the northern tip of Sweers Island. It has not been visited.

The Landscape: At sea.

Point information: Ken Granger, 2008.

WITHIN THE DEGREE SQUARE

The Country: The bulk of the half square is made up of the waters of the Gulf of Carpentaria. The only land in the square is made up of Sweers Island, the eastern half of Bentinck Island, the Cape Van Diemen end of Mornington Island and a small section of mainland around the delta of Gun Arm Creek.

Most of the land is less than 10 m ASL and of aeolian or marine sediments of Quaternary age (less than 2 million years). The highest point, at 29 m ASL, is Inspection Hill at the southern end of Sweers Island. This area, together with sections of Bentinck Island, is made up of Cretaceous age (around 100 million years) sandstone and limestone. Vegetation is of low open eucalypt savannah with tussock grass as ground cover. On the mainland mangroves and samphire are the main types encountered. None of the land in the degree square has a good reliable source of fresh surface water.

Marine fauna includes estuarine crocodiles, dolphins, dugong and turtles.

The Climate: The area has a climate that is classified as being tropical savannah. It has a pronounced dry winter. The climate station at Mornington (Gununa) provides representative statistics that can be applied across the area.

 
Mornington Island (site 029039) 1914-2008 (elevation 9 m ASL)

 

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Year

Mean max
(ºC)

32.2

31.7

31.9

31.4

28.8

25.8

25.6

27.6

30.3

32.3

33.3

33.1

30.3

Mean min
(ºC)

25.5

25.5

24.6

23.2

20.2

17.2

16.1

17.2

20.5

23.6

25.7

26.2

22.1

Mean rain
(mm)

320.3

303.8

254.2

51.7

9.4

6.9

2.5

0.8

1.3

12.7

55.6

155.0

1182.5

The highest temperature ever recorded at Mornington Island was 39.6°C in December 2004 while the lowest temperature was 5.1°C in July 1974. Rainfalls also vary greatly. The highest total of 2171.4 mm was recorded in 2006 and the lowest total of 64.6 mm in 1997.

Extremes of Nature: The area is very much subject to the impact of cyclones. The database maintained by the Bureau of Meteorology shows 63 cyclones have tracked within 200 km of the confluence point since 1906. Ten cyclones have tracked within 50 km of the confluence point. They included: an unnamed cyclone in January 1907; an unnamed cyclone of April 1921; an unnamed cyclone in March 1939; an unnamed cyclone of February 1949; TC Yvonne in February 1974; TC Greta in January 1979; TC Jason in February 1987; TC Steve in March 2000; and TC Fritz in February 2004; TC Raymond in January 2005. Most of these storms originated in the Gulf of Carpentaria. They each produced destructive winds, heavy rain and high seas.

In the early 1870s a cyclone produced a storm tide that reached a height of 3 to 4 m and again in 1887 a similar storm tide impact was experienced. In January 1948 an unnamed cyclone passed over Mornington Island and produced a storm tide that destroyed the water supply of the community on Bentinck Island.

Perhaps the most difficult issue with cyclones in this area is the generally short warning time available because they tend to form very close to the coast and islands. The short warning time can be especially dangerous to mariners in the area, especially people in small boats.

cyclones

Cyclone tracks within 200 km of the confluence point since 1906 (Bureau of Meteorology web site)

The area experiences between 50 and 60 thunder days per year. Severe thunderstorms can bring destructive winds, intense rainfall that can produce flash flooding and lightning. Sea conditions during these storms can become very dangerous very quickly. Storms in the dry winter period can spark bushfires if there is sufficient fuel to promote spread.

The National Earthquake Database maintained by Geoscience Australia shows only one small earthquake in the degree square, a ML 2.2 event of 2 February 1938 located in the north-east of Mornington Island about 77 km north-west of the confluence point. No damage was reported from this event.

The Indigenous Story: The area is the traditional home of two Aboriginal groups. Mornington Island is Lardil land; and the South Wellesley Islands are Gayardilt land.

The Lardil and Gayardilt peoples had little contact with the outside world before the early 1900's. Pre-contact they lived in family groups of 15 to 20 people who owned a portion of the land and water. Contact with Europeans in the 1860s to 1880s were generally peaceful, however, a clash occurred in 1918 on Bentinck Island that left at least 11 Aboriginals dead. Even as recently as 1942 an armed clash occurred on Sweers Island. In that year some members of the RAAF the radar station on Mornington Island visited the Island and were attacked by some Aboriginals throwing spears. The servicemen fired several shots in reply killing one man and wounding a woman.

Following the establishment of a mission on Mornington Island and during the 'protection era', some children from tribes on the Gulf islands were removed from their families and brought to Mornington. In 1948, after a storm tide devastated their water supply, all of the Gaiadilt people were brought into the mission from Bentinck Island.

European Exploration and Settlement: The first known European survey of the coastline of the area was that undertaken by Abel Tasman in 1644. It was Matthew Flinders in the Investigator in 1802, however, who made the first detailed survey. He landed on Sweers Island in November 1802 and took sightings from Inspection Hill. He named Sweers Island in honour of Salomon Sweers, one of the Councillors of Batavia who had authorised Tasman's voyage. Flinders established a camp on Sweers Island and his men caught fish and shot bustards to supplement their rations and opened up an Aboriginal well to replenish their water. Members of his crew inscribed the name of their ship on a tree near a point on the western side of the island.

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