Total solar eclipse 4 December 2002

in South Australia

Location Report for the Stuart Highway between Pimba and Glendambo
part 1 of 2

Stuart Highway map

Click here to download a high-resolution version of this map (5.0MB zip).

If you have come directly to this page from another website; you can find my other eclipse information here.

The photos on this page were taken on cloudy days in mid-winter; so the sunlight is much less intense than what is expected for eclipse day. You may also find some of the images and descriptions in the Roxby Road Location Report to be useful.


leaving Port Augusta This road sign is at the southernmost end of the Stuart Highway in Port Augusta. And yes, it was raining when this photo was taken! The name of the highway commemorates the Stuart Expedition of 1862; which was the first successful south-to-north crossing of Australia. In fact they also crossed Australia north-to-south too, because they had to retrace their steps for their return home.

General notes

The land between Pimba and Glendambo has been subject to erosion for most of the last 500 million years, and during the last 50 million years has changed from a wet temperate woodland into a desert as the Australian continent has moved northwards. Consequently the land has almost no topographic relief, except for sand dunes and the local drainage-related gullies and depressions around the salt lakes. There are a few remnant mesas of Jurassic and Cretaceous rocks, formed when the southern edge of a shallow inland sea briefly covered some of this region. At the eastern end of this map, the northern and western shorelines of Island Lagoon mark the boundary of a major erosion escarpment, whch separates the lowlands northwest of Port Augusta from the slightly higher country mapped here.

The lake basins shown here - which have no drainage to the sea today - are believed to have been initiated by mild tectonic downwarping and/or water erosion of softer regions during the Jurassic and Cretaceous eras. The depressions so formed have been enlarged and deepened by subsequent wind erosion; a process which continues to the present day. In the case of Lake Gairdner and its neighbours, these processes were certainly assisted by the tremendous fracturing of rock caused by the 53-trillion-megatons explosion of the Acraman Impact about 590 million years ago.

Sands eroded into the lakes are eventually blown out again to form sand dunes, principally around the lakes' downwind shores. These shores are also eroded by waves when the lakes occasionally fill with floodwaters. More often, any lake water is merely a huge saline puddle, which can be blown considerable distances across the lakebed by the wind. When the water finally evaporates, the silty and muddy sediment on the lakebed combines with the salt to form a smooth crust; baked hard by the Outback sun. But in some places this crust can be fractured by the weight of a vehicle -- or even the pressure of your footfall -- causing the unlucky traveller to sink into a soft morass of saline ooze. This ooze can be many metres deep. Many vehicles and animals (and a few people) have been lost to this hazard.


regolith

The land alongside the Highway consists almost entirely of a deep and heavily weathered regolith, which is itself covered either by a loosely-compacted skin of sand & clays, or by large expanses of gibber stones concentrated at the surface as shown here (with Nokia 5110 for scale). Driving over gibber stones at speed will throw up rocks which may cause significant underbody damage to your car - for example to its brake hoses and fuel lines - or cause multiple tyre punctures.

In many places there are extensive areas of sand dunes 1-3 metres high; or broad sand patches where dunes once stood. These sandy places support open-canopy arid woodlands of centuries-old mulga trees (Acacia sp.), growing up to about 5 metres high. Callitris pines up to 8 metres high may also grow on the larger sand dunes. In the stony areas, and between the trees themselves, the vegetation is a sparse mixture of low plants, mainly saltbushes and native grasses.

Despite its harsh appearance, this country does support a surprisingly large population of sheep, cattle, kangaroos, emus, and smaller native wildlife. Including many species of venomous (and sometimes aggressive) snakes... Closer examination can reveal subtle beauties in this landscape; for example the delicate tracery of dew on tiny cobwebs, the brilliant red fruits of Atriplex versicana, and the colours of local birds.

After rain, the clays in the regolith transform it into a glutinous slippery mass with almost zero traction and load-bearing capability. Heavy rain will cause widespread flooding and consequent road closures, sometimes lasting for weeks. Just about any wheeled vehicle attempting travel in such conditions will get bogged.


Stuart Highway embankment & road train

To alleviate this flood risk, much of the Stuart Highway is elevated upon a low embankment of crushed rock across this region, as shown here in this photo of the Centreline Ute parked about 15 km west of Pimba. Complete with a genuine Aussie road train in its natural environment.... Nowadays it is rare for the Stuart Highway to be closed by flooding. But in many places this embankment, or dense scrubby vegetation alongside it, may make it difficult or impossible to get your car completely off the Highway. Sharp sticks and rocks accumulated at the very edge of the embankment may damage tyres or other parts of your car as you drive over them. Adding to the problem, some of the land surface beside the Highway has low mechanical cohesion even when dry; so it's possible to bog your car in it if you're careless. Driving over the vegetation will cause some of it to be caught by your car's underbody components, and if some of this debris touches your hot exhaust pipe, then you will start a fire beneath your car.... So drive carefully if you go off-Highway.

road train on Stuart Highway

If you cannot get completely off the Highway in safety then you will be compelled to park on its gravel borders. Typically these are only about as wide as your car, so you will be close to road trains and other passing traffic. As typified by this photo of the Stuart Highway - complete with another road train - going through a belt of dense scrub.


warning

Visitors are warned that driving at night in this region is hazardous! The roads are unfenced, and larger animals use the roads as easy pathways to their sources of water or food. The local grey kangaroos will often jump in front of an oncoming vehicle, because of their "if I'm scared, move into a clear space where I can see easily..." instinct. At night this clear space is the road surface illuminated by your headlights!

A kangaroo impact with a vehicle usually kills the 'roo and can cause significant damage to the vehicle; unless it is fitted with protective bars. Ditto for sheep impacts. Impact with cattle will kill the animal, demolish your car, and may seriously injure or kill you and your passengers. Avoid driving at night on the Stuart Highway. The regular nocturnal traffic, mostly trucks, road trains and long-distance buses, kills large numbers of animals on the Highway every year. These vehicles have two advantages over the typical car: massive protective bull bars on the front, and an overwhelming weight advantage. Even an 800-900 kg bull is no match for a 60-ton truck, or a 150-ton road train....



South of centreline on the Stuart Highway.

road train

This description begins at the tiny settlement of Pimba, 170km (road distance) northwest of Port Augusta. Pimba is basically just a pub and service station (Spud's Roadhouse), a Trans-Australian Railway siding - where some eclipse tours are going to be parking their trains - and a few houses. Pimba is a popular stop for the road trains, as shown here. It is also the turnoff from the Stuart Highway to Woomera, Roxby Downs and Andamooka. Location Reports are provided for the Roxby road / Andamooka region and for the Woomera Prohibited Area. Pimba itself gets a 99.5 percent partial eclipse on December 4.

A site of interest to spaceflight enthusiasts is the former NASA tracking station of Island Lagoon; used for many of their 1960's space missions. The bitumen turnoff from the Stuart Highway to this publicly-accessible site is about 10km southeast of Pimba. Little remains there today apart from the concrete foundations of the 26 metre dish and its associated buildings - and an excellent view over the Lagoon itself. A second turnoff about 1 km southeast of Pimba leads to the former US surveillance station of Nurrungar. All public access to Nurrungar is prohibited; and this is enforced by fences, road barriers, and military patrols.

The town of Woomera, 7 km by road north of Pimba, is open to public access. Many artefacts from its military and spaceflight history are on public display; including actual aircraft, missiles and rockets.

Travelling west from Pimba, the Highway continues over a treeless stony plain for about 20 km, before entering a region of low scrub-covered sand dunes around the northwestern end of Island Lagoon. The Highway cuts across a low-lying arm of the Lagoon 33 km from Pimba, before entering more sand dunes. This time with low but ancient mulga trees on them. The Lake Hart lookout and carpark is on the north side of the Highway, 41 km from Pimba. It's worth stopping for a photo of the lake, whose distant northeastern shore once featured 7-storey-high launchpads intended for European satellites. Many people choose to camp here overnight, but you may be disturbed by trains on the nearby railway line along the lake's shore. This carpark is only 6 km outside the eclipse's southern limit.

A cattlegrid about 52 km from Pimba warns that you are near the eclipse's South Limit, which is 53.4 km by road from Pimba. If eclipse day is unusually cold (eg: 10 C instead of 30 C) then atmospheric refraction could move the South Limit 0.5 km (road distance) closer to Pimba. Coincidentally near to South Limit, the mulga-covered sand dunes near Lake Hart give way to flatter sandy country with fewer trees, as shown in the panorama below. This panorama was taken about 3 km (road distance) inside South Limit, and will get a totality of about 16 seconds.

Unfortunately the film used for this panorama was an old roll, and upon development it was discovered that its colour balance was faulty. Colours on the left (east) end of the panorama are almost correct. The rest of it needs some serious work! Nevertheless it will give you a good idea of the landscape and eclipse viewing obstructions here.

57km from Glendambo
Click here to download a high-resolution version (543kB zip).

Continuing west, the next significant landmark is the turnoff to the Wirraminna homestead, 59.4 km by road from Pimba. Their large entrance signs - which will see 21.8 seconds of totality - would look good in your eclipse group photo. The Wirraminna homestead itself is further off centreline and gets just over 20 seconds of totality.

The first cattlegrid west of Wirraminna turnoff is close to where the 80-percent-of-duration line crosses the Highway. The next cattlegrid is about 200 metres east of the 90-percent-of-duration line, and soon after you should be able to see the Wirraminna rail stop's radio mast towering above the scattered trees. An inconspicuous dirt track, starting alongside a cattlegrid 69.7 km road distance from Pimba, provides vehicle access to the Wirraminna rail stop. If you're coming from Glendambo, the cattlegrid is 46.8 km by road from there.

Wirraminna rail stop is simply a two kilometre long siding on the Trans-Australian Railway, built solely to allow trains to pass each other. Because I've come across some fantastic rumours about this place on the Net, I provide here two sets of panoramic photos from the northwest end of the siding, which together show a full 360 degrees view. The only visible structures are the solar-powered radio tower to the southeast, used for the railway's own communications; a concrete water tower to the northeast (just inside the Woomera Prohibited Area), and the concrete shell holding batteries and controls for the railway points shown here at the northwest end of the siding. The Centreline Ute is parked east-southeast of the camera. Note the absence of anything resembling tourist facilities! As the photos suggest, the railway is on an embankment which would permit a trainload of tourists to see the eclipse above the local trees. This northwestern end of the siding gets 29.5 seconds of totality. The southeast end gets one second less.

wirraminna rail stop north side
wirraminna rail stop south side

Click here to download high-resolution versions of these two panoramas (743kB zip).



CONTINUE to part 2 of this report....


Copyright © 2002   Fraser Farrell. All rights reserved.