Hottentots Holland Crossing EarthCache
Hottentots Holland Crossing
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Located at a lookout at the top of Sir Lowry’s Pass. Be aware of baboons – they are WILD! Please do the cache at the top of the nearby hill too.
Depending if you are traveling to or from Cape Town (i.e. west or eastwards), the approach to this cache is quiet different. Traveling from the east towards Cape Town you would have been traveling through the Bokkeveld Group and only on leaving Elgin and reaching the top of Sir Lowry’s Pass would you start encountering the Table Mountain sandstones. Both of these form a part of the Cape Supergroup.
However moving from Cape Town and leaving Table Mountain behind you, you pass over the wind blown (Aeolian) sands of the Cape Flats and approach the impressive Hottentots Holland mountain range in front of you. Once past the last exit to Gordon’s Bay, you start the fairly rapid ascent up the Sir Lowry’s Pass. Although the rocks here are identical top those on the upper reaches of Table Mountain – note that the almost horizontal layering and homogenous (unbroken) layers so evident on table Mountain are not as evident here. This is because we are now well and truly into the Cape Fold Belt and the layers are tilted and many broken blocks of rock are evident. This is the zone where the Cape Fold Belt changes it’s orientation from being north-south following the Atlantic coast up towards Langebaan and the west coast, to a more east-west direction following parallel to the southern coast. Transitional zones like this are generally known for their brittle fracturing of the rocks, rather than the more characteristic folding that is so evident elsewhere in the fold belt.
A few kilometers down the Pass (the 11.0 km blue highway marker) towards the bottom of the ascent (do be careful and ensure you pull off at a safe spot if you stop here), you can see some “freshly” exposed Cape Granite on the road cutting on the side opposite the sea. Remember that the Cape Granites underlay the Cape Supergroup sediments – and are exposed at places like Paarl and along the coast (see Froggy Pond and Darwian Contact earthcaches too).
At the 11.8 km blue highway marker and most of the way to the top (actually if you walk from the waypoint of the cache – through the small pedestrian cutting towards the highway, this is clearly visible – you can start seeing the sharply dipping Table Mountain quartzite and sandstones. The dipping varies and can be up to 60° in places! Less than 50km from the almost horizontal Table Mountain! These dips can be observed right across the top of the Pass and even in cuttings and exposures closer to Elgin.
(Acknowledgments: Geological Journeys.; Norman & Whitfield; 2006).
Another excellent cache belonging to Discombob (View from the Top: GCM95F) lies just at the top of the nearby outcrop. Well worth the effort of a scramble to the top for more stunning views of the Hottentots Holland range and an opportunity to get up close and personal with fresh quartzite and sandstone exposures.
In order to qualify to log this cache, you need to answer the following questions and email the cache owner. Any logs not accompanied by an email will be deleted.
1) Take a photo of you and your GPSr at this spot with any nearby geological feature (or the plaque) visible and include in your log. [Optional]
2) Look at the exposed quartzite/sandstones that are exposed. See if you can identify any of the structures or features described above. Include comments in your email – and photos too – if you found them interesting.
3) Look for the weathering on the outcrop across the carpark (towards cache GCM95F), and explain what material is visible in the “new” sand.
4) What chemical is the main component of quartz?
5) Give an explanation on how you think the folding may have occurred in this region.
Additional Hints
(Decrypt)
Erzrzore gb fraq lbhe rznvy!