January 20, 2014
Monday Geology Picture: Shipwreck on Noordhoek Beach, South Africa
Posted by Evelyn Mervine
Sometimes, manmade objects become part of the geological landscape. For example, on Noordhoek (which means “North Corner”, in Dutch and Afrikaans) Beach near Cape Town, South Africa, there is a shipwreck at one end of the beach. Two rusted boilers and a ring of metal ribs– sticking up out of the sand like a picket fence– are all that remain of the S. S. Kakapo, a New Zealand steamship that became stranded on the beach in 1900. You can read all about the wreck of the S. S. Kakapo here. In this Anthropocene time discarded manmade objects no doubt have a big impact on the Earth and its various processes. While the remains of the S. S. Kakapo likely have a fairly small impact on the environment, the skeletal shipwreck nonetheless reminds me of the traces we humans leave behind. 114 years after the shipwreck, the ghostly metal outline of the S. S. Kakapo remains.
Nice to see this post on the AGU website, especially as a longtime media associate.
As a resident of the area it is interesting to note the annual changes of this dynamic beach which advances and recedes over the years. It is neat to take a look at google earth and zone down onto this wreck and then go through the history of the various google earth images. It immediately becomes evident just how dynamic the beach shoreline is. While some of the shifts are tidal, the tides here are negligible, only around 1.5m on average.
But most interesting of all for me is that the wreck has remained at least 100 meters from the beach over my lifetime (been visiting the beach since the 1960s!) yet the beach dunefield that shifts sands through the valley has been stable since at least 1925, thus sand recharge from the SE side has not occurred since then. Therefore there is probably large amounts of sand accretion from winter storms, which seems to be supported by the recent google earth images.
This is in contrast to other beaches in this area which are supplied with sand from other zones and which have been isolated because of urbanisation or dune stabilisation. Some of these beaches, eg Sandy Bay, are rapidly being eroded and diminishing in size because of this recent human interference in the sand transport mechanism.