Many thanks to the NMMU for allowing us to use the NMMU Private Nature Reserve for geocaching. Please abide by their rules.
You will need to follow the Grysbok trail marked with yellow footprints to get to ground zero.
The NMMU campus was declared a Private Nature Reserve in 1983. The campus covers 830 ha, and is dominated by the St Francis Dune Thicket vegetation community, which is characterised by clumps of thicket occurring within a matrix of Dune Fynbos.
The following strict rules apply:
1. Entry to the reserve is free but everyone must sign the visitors book found at the entrance to the reserve.
2. No vehicles are allowed in the reserve.
3. No fires are allowed in the reserve.
4. The reserve may only be used during daylight hours.
5. The rangers have provided the following cell numbers in case of emergency. 082 5368 192 & 083 4468 564
Grysbok Nature Reserve Geology
The campus lies on an old marine platform cut by wave action at a time when the sea level was higher than at present (15 million years ago). Three rock types may be encountered on campus. The oldest is a hard grey-white quartzite, known as Table Mountain Quartzite (TMQ), which crops out in several road cuttings. Layers of calcrete, old “beachrock” and dune sand overlie the TMQ. The calcrete is a fine-grained, creamy coloured rock that forms the substrate along the trail. It is formed when groundwater dissolves shell fragments in the sand, which is then precipitated as layers of calcrete. (Note: only the dune sand and calcrete horizons are exposed on the trail). Modern dune deposits occur throughout the area. Most common in the reserve are transverse dunes, with crestlines oriented at about 90 ° to the prevailing winds, which blow from the southwest and east. Also present are parabolic dunes, which form parallel to the prevailing winds. Their shape is influenced in part by vegetation patterns.
The dunefield is about 6000 years old, and forms part of a headland bypass dunefield, which once replenished Algoa Bay beached with sand by overland wind transport. Following the artificial stabilisation of the dunefield in 1870, the headland bypass system was fixed by plant growth and is now largely inactive.
The Geology of an area is very important because it directly shapes plant communities. The plants, in turn, determine what types of animals can survive in the area. As the name "Dune Fynbos" implies, much of the trail lies on an old dunefield.
To log this earth cache you need to answer and e-mail the following questions:
Approximately how old is the Grysbok dune fields?
What dunefields are the most common in the Reserve?
At Ground zero you will see a sign with one of the strata's information on, name it and explain how it is formed and how old it is according to the information sign?
Explain the colour of the this example located around the signboard.
As an added request please take a pictures of yourself at GZ or the start of the trail. Please also mention animal species seen whilst doing the trail in your log.
Source: http://grysbok.nmmu.ac.za/