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Mirror, mirror on the wall EarthCache

Hidden : 1/14/2010
Difficulty:
2 out of 5
Terrain:
1 out of 5

Size: Size:   not chosen (not chosen)

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Geocache Description:

Although this cache concerns sandstone formations, it has a twist involving a (human) granite intrusion, our nearest star, the Sun, and the death of a mortal, now remembered by an elusive "star" occasionally seen shining in the Seven Sisters.


Please Note: This cache is best suited to be done in the (late) afternoon when the illumination of the Sun brings out these features best. But for the real challenge, you need to be at a specific place at a specific date and time - more later.

The designated coordinates brings you to a spot with a stunning view of the Hawekwa mountains behind Wellington. Incidentally, the name Hawekwa have more than one possible meaning. One explanation is that it is a Khoisan word meaning "the old man in the mountain". This is because the horizon forms the silhouette of the profile of an old man. A more likely explanation is that it is derived from the Khoi word "Obiqua" meaning "murder[er]" which was how the Khoi referred to the San (Bushmen). As you can deduce, there was not a lot of love lost between these two tribes.

If you are familiar with the geology of Table Mountain, you will notice some similarities here - in particular, the overlaying formation of the Hawekwas which consists of the Table Mountain Sandstone Group. If you look carefully at the crags at the top, particularly under the illumination of the late afternoon Sun, you will notice that the colour at the base of the sandstone sequence is distinctly red, compared to the light grey sandstones overlaying it. Like Table Mountain, the reddish sandstone and shale of the Graafwater Formation is followed by a thicker sequence of grey sandstone of the Peninsula Formation. Not only is there a colour difference, but these sandstones differ in hardness. The Graafwater sandstone decomposes much easier compared to the Peninsula formation which is 95% quartz. The latter erodes very slowly, resulting in the "clean" and white bolder-lined Witte River (hence its name, "White River") which runs parallel to the road when you ascend Bain's Kloof on the Ceres side. The main difference between these two mountains lies at their bases - Table Mountain has an underlying granite base where the Hawekwas has Malmesbury shale below which decomposes into rich soils as can be seen from the vegetation growing on its slanted base.

But there is also a tiny granite "intrusion" hidden somewhere in these sandstones - in the Graafwater formation to be exact - in a section of the mountain known as the Seven Sisters. This is actually a human granite intrusion that manifests itself under very special circumstances, almost like the illusive seventh star in the Pleiades (also known as the Seven Sisters).

To pick up the story we need to backtrack to 19 November 1959 when two local boys, Piet Hugo from the farm Hexberg and Frans Ferreira, the only child of the then police chief of Wellington, during their university vacation, set off that Thursday morning to climb the Hawekwas. Frans's beloved Doberman went along and as the party went through the farm Patatskloof, the then owner, Sarel van der Merwe warned them about the wisdom of taking a dog to the mountain. Frans replied that his dog was used to climbing but Sarel's reservation soon came true when the dog got stuck on a narrow ledge high up on a cliff. In an attempt to lift his dog to safety, Frans lost his balance and fell to his death. Although his heroic deed saved his dog's life, story has it that the dog later mourned itself to death.

Needless to say, the Ferreira's were devastated by the tragic death of their only child and decided to erect a headstone, cemented to the rock-face lower down on the mountain. It is unclear if it was intentional or not, but this stone, being made of highly polished granite, very effectively reflects the light of the setting sun, sweeping a bright beam across the full width of the town of Wellington. In fact, since most people cannot believe that an almost black stone can produce such a bright reflection, a fairly general story developed stating that a real mirror was put next to the plaque to produce the light. However, this was proved to be a mere legend when we visited the site in 2002. (If you want to visit it, the approximate position of the plaque is S33 40.293 E19 04.639.)



A small group of people gathered at the plaque during the unveiling ceremony. (Source: Wellington Museum)


The unveiling of the plaque with Frans' farther looking on. (Source: Wellington Museum)


My son (left) and I posing at the plaque during our 2002 visit.

From when I first heard of the story of the "Hawekwa Mirror", I was intrigued but found that, no matter how much I enquired, nobody could tell me when to look where to see this illusive phenomena. It was only until I was tipped off by Jacques Retief (incidentally also born and bred on a subdivision of the original Hexberg farm) that the "mirror" was visible from Hexberg - so I first managed to see it for myself on 27 January 2002. I was amazed by how bright it was, making me understand how the legend of a real mirror could have came about. I actually calculated it to be slightly brighter than the full Moon, all concentrated into a single point. Using my astronomical and mathematical background, I calculated visibility predictions for when and where the reflection should be visible and followed it for a few months to verify my predictions. With an article in the local paper, I alerted others to share this phenomena and published a more scientific article in the journal of the Astronomical Society about it. My research was also included in a project where the complete history of Wellington was recorded - a copy can be viewed at the Wellington Museum. It was a really rewarding exercise indeed! (View a 30 minutes 'footage' taken through a telescope at 70 power.)

You can also share in this experience by doing this EarthCache. To see the reflection you need to be at the designated coordinates within about week around 04 February @ 19h00 or around 07 November @ 18h30. If you cannot make it then but you want to hunt down the reflection at some other time, this image can be used as a guide for where and when to see it (or get this GPX-file accompanied by this list to do your own detailed predictions). Note that these are only guidelines (allow about a week and ten minutes around the predicted dates and times). Visibility also depends on local conditions like clouds around the Sun or low on the mountain which will spoil it. Having a printout of this picture (reflection arrowed) with you will help you to know where to look. (Note: the mountain looks slightly different from different angles.) Also note that you can lengthen the visibility period slightly by using binoculars. Although it is ideal to see the reflection when doing this cache, it is not mandatory to qualify for "Found it".



A picture of the reflection (arrowed) taken from the cache coordinates on 4 February 2002 at18H58. The rectangle refers to Q.1 below.

To claim "Found it" you must email me satisfactory responses to the following:
Any logs not accompanied by an email will be deleted.

  1. Compare the area in the rectangle in the above picture with the corresponding area on the mountain. What do you see is different?
  2. Identify an area on the mountain where the Graafwater sandstone is most obvious. Send me a picture of you/your party with your navigation device showing this area in the background.
  3. If the order of the sandstones were reversed, ie the Peninsula formation was below the Graafwater - would these mountains have been higher or lower than they are today?
  4. As a bonus, if you managed to spot the reflection of the Hawekwa "mirror", send me the date, time, GPS coordinates and description of your observation.

Note: Do not post any spoiler pictures/hints to this page, even if encrypted.

Additional Hints (Decrypt)

Ernq gur grkg pnershyyl, nyy gur pyhrf ner va gurer. Rznvy lbhe nafjref gb jcx@fnnb.np.mn

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)