This EarthCache is located at the summit of St Mary Peak (1171m) in the Flinders Ranges.
St Mary Peak, is situated on the north western side of Wilpena Pound, and is the highest peak in the Flinders Ranges, South Australia. It lies within the Flinders Ranges National Park. St Mary Peak is the eighth highest peak in South Australia.
The aim of the cache is to learn about the geology surrounding Wilpena Pound. It is also to share with you the spectacular views from the peak and the distant Outback. In order to log this EarthCache you must visit the summit of St Mary Peak. You will need to email us the answers to the questions in Logging Requirements below, as well as upload a photo of your visit at the GZ coordinates to claim your find.
The Flinders Ranges National Park is located 450 kilometres north of Adelaide in the central Flinders Ranges, between the townships of Hawker and Blinman. The park comprises approximately 95,000 hectares and includes the Heysen Range, Brachina and Bunyeroo gorges and the breathtaking Wilpena Pound. St Mary Peak rises to 1171 metres above sea level and may be accessed via one of two walking trails from Wilpena Resort.
- The Outside Trail – This is the most direct route. It is a steep challenging hike of 14.6 km and is estimated at 6 hours return.
- The Inside Trail – This is less steep although none the less challenging route. The route is 21.5 km and is estimated at 9 hours return.
Mild temperatures from April to October make this period the most comfortable for walking. During the November to May, day time temperatures range from 30°C to 45°C making walking more difficult. Some walking trails may be closed on days of Extreme Fire Danger.
No matter what time of year you are visiting, a careful responsible approach to bushwalking is essential for your safety.
- Flinders Ranges National Park is subject to entry fees
- Be prepared, and carry relevant maps & compass or GPS, sunscreen and appropriate clothing.
- Take plenty of water with at least 4 litres of water per person.
- Log your details in the Bushwalkers Register at the Wilpena bushwalking trailhead or the visitors centre.
- Inform someone of your planned route and expected time of return.
- Study the trailhead sign and follow the well laid out trail markers.
For further useful information about the Flinders Ranges National Park click here. For information about bushwalking in the Flinders Ranges click here.
Landscape
The Flinders Ranges is the largest mountain range in South Australia and starts approximately 366 km north of Adelaide. The discontinuous ranges stretch for over 430 km from Port Pirie to Lake Callabonna.
It’s most characteristic landmark is Wilpena Pound, a large, sickle-shaped, natural amphitheatre covering nearly 80 square kilometres, containing the range's highest peak, St Mary Peak (1,171m) and adjoining the Flinders Ranges National Park. The northern ranges host the Arkaroola wilderness sanctuary and the Vulkathunha-Gammon Ranges National Park. The southern part of the ranges are notable for the Pichi Richi scenic railway and Mount Remarkable National Park
Several small areas in the Flinders Ranges are protected as National Parks. These include the Flinders Ranges National Park near Wilpena Pound and the Mount Remarkable National Park in the southern part of the ranges near Melrose. The Arkaroola Wilderness Sanctuary is a scenic protected area at the northern end of the ranges. In addition, the Dutchman's Stern Conservation Park, west of Quorn and the Mount Brown Conservation Park, south of Quorn, are protected areas of the ranges. The Heysen Trail and Mawson Trail run for several hundred kilometres along the ranges providing scenic long distance routes for walkers, cyclists and horse-riders.
Geology
The Flinders Ranges are a part of an upland geological formation that stretches from the southern coast of South Australia to the Eyre Basin, about 600 km. The elevation of almost all of the ranges is above 300 m, and the highest elevation is St Mary Peak at 1171 metres.
The rocks of the Adelaide Geosyncline that were deposited as sediment along a passive margin of the supercontinent Rodinia form much of the Flinders Ranges. About 540 Million years ago, in the Cambrian, the Delamerian Orogeny thrust up the rocks of the Adelaide Geosyncline, faulting and folding it to form a large range, the eroded remnants of which are now the Flinders Ranges. The rocks of the Ranges are mostly quartzites, limestones, shales and sandstones.
The rocks composing the Flinders Ranges are believed to have been deposited in shallow seas between about 850 and 500 million years ago. The Adelaidean Sea which is similar in size to that to the Mediterranean Sea, stretched into central Australia from Kangaroo Island. The subsiding sea floor was a depotcentre for the sediment from the eroding higher ground to its west. As the climate changed, so did the deposition of these sediments. The coarseness and colour of the alternating layers resulting from the climatic changes can now be read in the rocks, allowing a climatic history of the area to be read from the rocks.
About 600 million years ago, while Australia and Antarctica were still a single continent, the seafloor along their east coast began to plunge beneath them along 4,000 km of their coastline. The mountain chain pushed up by this event ran the full length of the Gondwanan east coast. The mountain chain is now in two parts, the Transantarctic Mountains in Antarctica and the Flinders Ranges in Australia. During this process the entire eastern part of Australia was added to the much more ancient western section. For most of the length of the Flinders Ranges the rocks they are formed of were sediments that had been accumulating since before 1.0 billion years ago. The far northern end of the chain is composed of 1650 million year old granites and other crystalline rock.
The original ranges had been reduced almost to the level of the surrounding plains by about 60 million years ago. Minor earth movements rejuvenated the area, thrusting the area up into a vast plateau that has since had the softer rocks eroded away to leave the harder rocks such as quartz as folded ridges of the present ranges.
Logging Requirements
In order to log this EarthCache you must visit the summit of St Mary Peak. You will need to email us the answers to the questions and upload a photo of your visit at the GZ coordinates to claim your find. Please do not post any answers to the questions in your log, as it will be deleted.
There is no need to wait for a confirmation email to log your find. We will read each email to confirm your answers and will contact you if there is a problem. Please do not email us photos, just upload them with your log.
If we do not receive an email in a timely manner after logging your cache, we will delete the log.
Internet finds are not permitted and will be deleted. You must visit the GZ after the date this EarthCache was published to claim this find.
Questions:
1) Where does St Mary Peak rank in the highest peaks of South Australia?
2) What is the colour and texture of the rocks at the GZ near the summit?
3) What is the angle of bedding of the rock strata and which way are they facing?
4) Look at the terrain to the north. Then look to the terrain to the east. What is the difference between the terrain to the north and the terrain to the east?
The famous photo. In your log please include a photo of your visit facing west at the GZ coordinates. As proof you have visited the GZ, the photo should include your GPS. Optionally you can include yourself or your caching group. A photo is required to verify your log.
References
- National Parks South Australia
- Department of Earth & Environmental Sciences, University of Adelaide
- Australian Journal of Earth Sciences
We hope you enjoy our third EarthCache
