Mt Gunderbooka is the major geological feature in the Gundabooka National Park, approx 40km SW of Bourke. The mountain and nearby Mt Oxely are in start contrast to the surrounding flat plains, The area is of great cultural and spiritual significance to the Ngemba and Kurnu Baakandji people and also has an important role in the pastoral history of European settlement.
Access to the park is via well made dirt roads, however these can be closed when wet to protect the tracks. Please check the weather when attempting to access this Earthcache. The park has a number of bush camping grounds and some accommodation in station buildings. Please contact the NSW National Parks and Wildlife Service for information on camping and accommodation. Note that the site for this Earthcache is day use only.
This Earthcache will take you on a short (~750m) walk from the picnic area to an observation point and a short way along the beginning of the Valley of Eagles summit trail to the second reference point.
Although it is not required for this EC, the hike to the summit of Mt Gunderbooka is thoroughly recommended and well worth the effort. It is a 5.7km return, with estimated 3-4hrs time. We completed it in just over 3hrs, which included 45min-1hr at the summit. It is well-defined track, however it is a demanding walk with steep sections and rocky surface. This is a remote area with little to no mobile coverage and correct equipment, vehicle, sufficient water and adequate footwear are required. Temperatures can be very high in summer. Please observe all safety precautions, especially if continuing on to the summit.
How Mt Gunderbooka was formed:
According to the local Ngemba law, the ancestral creator (Biaime) created the landscape with help from the goanna (Googa), the echidna (Thikabilla), the emu (Noori) and the kangaroo (Bundah). After they had created the landscape, Googa laid down to sleep and Mt Gunderbooka was formed. Bundah went to sleep and formed Cooronga Peak, while Thikabilla laid down to sleep and formed Mt Oxely. Noori created Mt Grenfell. These mountains, the Darling River and Yanda Creek form an extensive travel network linking other Ngemba landmarks.
According to Western scientists, Mt Gunderbooka is an outcrop of quartzitic sandstone (Mulga Downs Group) that was deposited around 385 million years ago in the Devonian period. Older underlying rocks (Girilambone Group), dating from the Ordovician period (436 million years ago), outcrop to the north at Little Mountain. Pressures in the earth’s crust caused uplift and folding of the area in the Devonian and Cretaceous Periods and a syncline was formed giving rise to the Gunderbooka Range. The range today is the remains of this syncline. Sediments, deposited mainly in the Quaternary Period (last 1.8 million years), have subsequently blanketed the slopes and plains around the mountain range. These sediments consist generally of orange-red clay sands on green-grey clays over gypseous clays as well as arkosic gravels.
Weathering of the sandstone here is mainly by heating and cooling and frost cracking, resulting in sharp edged fragments, which form loose screes over the lower slopes and in gullies that carry water from rain on the summit.
The area over which the summit trail passes as it heads to the base of the climb consists of low rises, spearated by ephemeral watercourses which discharge rains that fall on the summit and the range. The occasional presence of water commonly results in watercourses being identifiable by larger trees which grow along them.
To claim this Earthcache:
Take the short walk from the carpark to the observation point and answer the following questions, with the assistance of the cache notes:
- Look around at the area surrounding the raked observation area and describe the terrain and the rocks you see. For example, are they large or small ? Do they look like they have broken off and come from the range ? If not, what could they be ?
- Do you think this is a watercourse and what causes you to think this.
Now walk along the summit trail to the second reference point and answer the following questions
- How do the rocks in this area differ from those at the first site ? Do you think these rocks originated in the range above ? What makes you answer this way ?
- Do you think this is a watercourse and why/why not ?
Final question
- River stones are traditionally made rounded and smooth as they are tumbled along by floodwaters as they get carried far from their origin. Are the rocks in the watercourse you have seen today smooth ? What does this suggest about how far they have travelled ?
Photos
Photos are not compulsory, but are definitely welcome, particularly if you do tackle the sumit walk, but please don't include spoilers !
References:
National Parks website: https://www.nationalparks.nsw.gov.au/visit-a-park/parks/gundabooka-national-park
Gundabooka Park management plan: https://www.environment.nsw.gov.au/-/media/OEH/Corporate-Site/Documents/Parks-reserves-and-protected-areas/Parks-plans-of-management/gundabooka-national-park-state-conservation-area-plan-of-management-050671.pdf