18°S 138°E Lawn Hill – Queensland by Degrees

AT THE POINT

18°S 138°E confluence, Google Earth

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Location: This confluence point is located on the Queensland-Northern Territory border on Bowthorn Station at the point at which the Nicholson River cuts the border. It has an elevation of about 100 m ASL. The actual point was not reached because of the lack of roads and the very difficult terrain. The photos are at the closest point achieved which was about 3000 m west of the point. Access to that point was by the road from Bowthorn Station to the Nudgtaburra Community in the Northern Territory, then by quad bike along the border. The site is on the border of Burke Shire. Doomadgee, about 90 km to the east, is the closest settlement.

Google Earth Image

Landscape: The actual point is on the south bank of the Nicholson River on the edge of a shallow gorge. The surrounding country consists of broken sandstone ridges with several cliff lines of more than 50 m in height. The sandstone in the immediate area of the point is of Mesoproterozoic age (1 600 to 1 400 million years).

The vegetation is Spinifex (Triodia spp) grassland with scattered Bloodwood (mainly Corymbia capricornia), and wattles on the ridges and Coolibah (E. coolabah) and River Red Gum (E. camaldulensis) along the river. Animals sighted in the area included brumbies and Agile Wallabies. Land use around the point is arid land cattle grazing.

Point information and photos: Tony Hillier, Kevin Teys, Bruce Urquhart, Dale Farnell, John Nowill and Mary Nowill, 2008.

IN THE DEGREE SQUARE

The Country: The topography of the degree square is complex and includes very rugged sandstone ridges interspersed with river channels along the western side and and outwash areas to the east. The area contains some of the most ancient rocks in Queensland with the oldest being volcanic material of Orosirian age (2000 to 1800 million years) and dolomite siltstone of Statherian age (1800 to 1600 million years) in the northern half of the square. The sandstones found around the confluence point also cover much of the southern half of the square. Maximum elevations are around 350 m ASL in the hills of the China Wall formation in the north-west and the hills of the Boodjamulla (Lawn Hill) National Park in the south. Lowest elevations are around 50 m in the lower reaches of the Nicholson River and other streams flowing to the Gulf of Carpentaria.

Vegetation communities across the square include grassy woodlands dominated by bloodwoods with an understory of black spear grass; and open spinifex grasslands. Riparian vegetation along the drainage lines includes Coolibah and River Red Gum communities.

Ridge
Typical woodland country (J&M Nowill 2008)

Nicholson River riparian vegetation (J&M Nowill)

Fauna in the area include numerous bird species including the purple-crowned fairy wren, white-browed robin, crimson finch and blue winged kookaburra. The most commonly seen marsupials are Agile Wallabies. Feral animals such as brumbies and cattle are also encountered. Arid land cattle grazing is the dominant land use. The Kingfisher Camp on the Nicholson River is a popular camping and fishing spot.

Kingfisher
Blue winged kookaburra (J&M Nowill 2008)Kingfisher Camp (J&M Nowill 2008)

Climate: The area has a climate that is classified as being tropical savannah. It has a pronounced dry winter. The closest weather station is at Wollogorang (NT), which is approximately 88 km north of the confluence, and has an elevation of 60 m.

 

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Year

Mean max
(ºC)

35.0

34.4

34.5

33.8

31.5

29.0

29.3

31.0

34.3

36.7

37.6

36.8

33.7

Mean min
(ºC)

24.3

24.1

22.7

19.7

16.0

12.2

11.4

12.2

15.8

19.8

22.5

24.2

18.7

Mean rain
(mm)

210.1

249.4

165.7

38.0

7.1

3.3

1.4

0.7

3.7

23.1

66.5

164.4

961.0

The highest temperature ever recorded in Wollogorang was 46.2°C in December 1990 while the lowest temperature was 0.1°C in July 1993. Rainfalls also vary greatly. The highest total of 1789.9 mm was recorded in 2006 and the lowest total of 417.7 mm in 1992.

These and other climate statistics for Wollogorang can be found at: Australian Bureau of Meteorology, http://www.bom.gov.au/climate/averages/tables/cw_014707_All.shtml.

Extremes of Nature: The area is very much subject to the impact of cyclones. The database maintained by the Bureau of Meteorology shows 37 cyclones have tracked within 200 km of the confluence point since 1906. Two cyclones have tracked within 50 km of the confluence point. They were an unnamed cyclone in March 1957 and TC Bernie in January 2002. Both of these storms originated in the Gulf of Carpentaria. They each produced destructive winds, heavy rain and flash flooding. Flash flooding in this sandstone country can generate landslides, especially debris flows in the steeper drainage channels. Very large boulders can be transported significant distances in such events. Perhaps the most difficult issue with cyclones that form in the Gulf is the generally short warning time available because they tend to form very close to the coast. Cyclone information for this area and all of Australia can be found at the Australian Bureau of Meteorology website, http://www.bom.gov.au/cgi-bin/silo/cyclones.cgi.

Cyclone

Cyclone tracks that passed within 200 km of the 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. Storms in the dry winter period can spark bushfires if there is sufficient fuel to promote spread.

Extreme heat is also a serious issue. The climate records for Wollogorang show that on average (over 26 years of records) the area experiences 140 days a year with temperatures over 35°C and 13 days a year with temperatures over 40°C. Such extreme temperatures can cause heat stroke and death if appropriate measures are not taken such as avoiding strenuous physical effort, keeping as cool as possible and drinking lots of water. Heat waves kill more people in Australia than all other natural hazards combined.

The National Earthquake Database maintained by Geoscience Australia contains one earthquake epicentre within the degree square, an event of 15 November 1995 located just inside the northern boundary of Boodjamulla National Park. The database does not give a magnitude for the event so it was probably a very small event. No damage was reported.

The Indigenous Story: The area has been occupied by Aboriginal people for at least 17,000 years and may extend beyond 30,000 years. The land to the north of the Nicholson River is the traditional country of the Garawa people while the land to the south is the traditional country of the Waanyi people.

MORE INFORMATION WELCOME

European Exploration and Settlement: The Nicholson River was named in 1845 by Ludwig Leichardt during his epic journey from the Darling Downs to Port Essington in honour of Dr William Nicholson of Bristol who, Leichardt stated, 'whose generous friendship had not only enabled me to devote my time to the study of the natural sciences, but to come out to Australia'. Augustus Gregory surveyed the general course of the river in 1856 as he returned from his expedition to the Victoria River district.

Grazing leases in the area were first taken up in the 1860s and went through many periods of difficulty including an outbreak of 'Gulf Fever' (a form of typhoid fever) in the 1870s and severe drought in 1903.

MORE INFORMATION WELCOME

Today: The total population of the degree square at each national Census since at least 1996 was less than 50.

Apart from continuing cattle grazing and seasonal tourism to places such as Kingfisher Camp on Bowthorn Station there is little activity in the area. The section of Boodjamulla (Lawn Hill) National Park that falls within the square is not easily accessed and is likely to remain a conservation area rather than an area that is open to regular tourist access.

The only roads in the square are natural surface and are easily closed in periods of rain.

Site Summary:

Location

On the Queensland -NT border where the Nicholson River
crosses the border

Access

Very difficult - the degree confluence was not actually reached

Terrain

Broken sandstone ridge country

Catchment

Nicholson River and the Gulf of Carpentaria

Geology & soils

Ancient sandstone with shallow sandy soils

Vegetation

Open grassy woodland and spinifex grassland

Land use

Cattle grazing

Climate

Tropical savannah with a winter drought

Population in degree square

Less than 50 at the 2006 census

Infrastructure

Limited to a few natural surface roads and station tracks

National Parks

Boodjamulla (Lawn Hill) NP

Compilers: Ken Granger, 2009

Edited by: Hayley Freemantle

References: various web sites including local governments, QPWS and Bureau of Meteorology.