Where on (Google) Earth #123?
posted in Geology, Google Earth, Podcasts, Where on (Google) Earth? |As I was saying at the end of the second PodClast, Péter Luffi has been hammering me with his two most recent WoGEs. And it’s hurt my blogging over the last month or so! Okay, that’s being a bit facetious, but there’s a grain of truth to it. I really think that not having new WoGEs to post has interrupted the flow of my blogging. Fortunately, I’m back in the win column, so hopefully it’ll get my blog juices flowing. Lord knows there have been plenty of exciting geologic events in the news to blog about as well as a host of new voices in the geoblogosphere. You will not, however, see a tag cloud here – I do have some standards. 
For a little change of pace I’m going back to an oblique view to highlight some topography. As always, the winner is the person who first posts the location of the feature(s) in question (latitude and longitude will suffice), but there’s lots of good geology to explain if you recognize the area…
No Schott Rule, since I’m not playing this round. 
Well, this one took me exactly one minute to find it, and nearly an hour to document it:
34.31S – 18.83E — sedimentary deposits of the mostly Ordovician Table Mountain Group (TMG) on the eastern side of the Vaalsbai (False Bay) in Western Cape Province of South Africa. TMG consists of three units: the Graafwater Formation (sandstones, siltstones and shales) at the bottom, the Peninsula Formation (mostly coarse pebbly quartz sandstones, probably river channel deposits) in the middle, and the Pakhuis Formation (tillites) on the top. I guess, the white cliffs in the front belong to the Peninsula Formation, but I’m not sure.
Hehehe, I’ve also found that Gigapan picture while searching for the geology around Rooi Els
Yeah, the strategy certainly had a luck component too… well, the shadows say it’s on the southern hemisphere; deep water on three sides suggests either a peninsula-like bulge or cape ‘looking’ westwards, or even an island; I decided to ignore the latter alternative for the beginning, because of the oldish topography and absence of visible young volcanism. So, I intuitively started with the Cape region in South Africa, because, as it was easier to check this first before browsing along the Chilean coast… Western Australia is pretty flat, so that wasn’t my priority.
Duh, I did not check the WoGE contest fast enough… that one is in my own backyard!
Anyway, if you’re interested, I uploaded a photo of the relevant 1/250 000 geological map:
http://cjoint.com/?fhl0YulH0x
As mentionned by Peter, we mostly see the (folded) TMG; on the map we can see
Os- Peninsula Formation (type locality, Cape Peninsula on the other side of False Bay);
Opa- Pakhuis formation (Pakhuis pass, North of the Cedarberg mountains on Clanwilliam-Calvinia road)
Sc- Cedarberg formation
Sg- Goudini formation (Goudini, near Worcester, W. Cape)
Ss- Skurweberg fm. (just not quite sure where that is, near Ceres I think)
Dr- Rietvlei fm.
The white ridge in the foreground seems to be that block of Os (Peninsula fm.) with a 30° East dip symbol between Rooiels and Pringle.
The basement to the TMG appears near Koeelbaai as dark grey/greenish patches on the map, of the late Precambrian Tygerberg fm., Malmesbury Grp. You can see where it should be on the top-left corner of the photo, that shows the extremity of Koeelbaai.
Recent deposits (mostly coastal, dunes & paleodunes) are Qs and Qw (Springfontyn & Witsand fms., althouh the terms are not in common use).
As you can see from the map, the area is gently folded (you can actualy see spectacular parasitic folds in the landscape somewhere inland of Pringle, I really do need to stop and make some photos).
At Rooiels, the coastal R44 (a spectacular road to drive, a few photos at http://jfmoyen.free.fr/spip.php?article161 if the server eventually works…) leaves the coast and goes inland, in a sort of a sandy corridor that apparently is within the Peninsula formation, surprinsingly…
Oops, sorry wrong links, the photos actualy are at http://jfmoyen.free.fr/spip.php?article122
JF
WoGE #124 is posted, enjoy!