Saturday, June 7, 2008

Glacial Deposits?

So on the subject of glacial deposits, imagine roaming around the field one day on the look out for any glacial deposited rocks, what would you be looking for exactly?

The idea is that a glacier can flow, due to the pseudoplastic nature of ice. Just think of this like: as the huge ice sheet moves and gains momentum, more bonds holding the ice lattice together breaks and thus makes the flowing easier.. So now the glacier flows and mows the hell out of the ground upon which it's flowing! Shame the poor Nardouw Subgroup of the Cape Supergroup discovered this like 300 million years ago when the Dwyka decided to mow it down!

The result of this encounter can be seen in a town called Nieuwoudtville, which is now famous for it's flowers, waterfall and glacial pavement!

Below is a view of this famous glacial pavement in all its glory. You can see here what I meant by 'mow the hell outta the Nardouw' the Nardouw here has these deep striations, distinctive of glacial flow.

And try and figure out these two guys are.. It's like when the power rangers come together and make a bi machine to fight the bad guys..

Oh and the other thing Nieuwoudtville is known for: Harbouring the fugitive of the Cape stratigraphy.. Who is this you may ask?! Well it's the guy who resides between the Malmesbury and the Cape Supergroup.. Any ideas?

Woah! It's the Vanrhynsdorp Group! Just there hiding below the Nardouw, he thought it was a good hiding spot, like my friend thought about his cave (enough said).. But then this waterfall totally uncovered him! Well there's something missing here.. Any ideas? Nardouw, ........., ..........., ............., Vanrhynsdorp. We don't give everything away you know..

Ok so imagine this big ice sheet glacier thing, the top we call Supraglacial, the bottom Subglacial and inside the thing Englacial, and these are basically the different places where you can get deposition of sediments being transported by the glacier.

In the case where sediments are deposited directly from the glacier onto the land, we call this Tillite, like our friend the Dwyka tillite! Dwyka really doesn't care who you are, if you're in its ways it'll just mow you down and maybe even take you with for a long road trip! Like some unfortunate Ventersdorp lava clast discovered:

Below, the blackish, fine grained rock is the Dwyka tillite, and here note the several smaller clasts that got in its way and just got kidnapped, especially the big green clast, viz the Ventersdorp lava, far from home (~1600km)!

On the topic about the Dwyka kidnapping, sometimes the boulders that they kidnapped becomes quite a las, then the glacier will Drop the problem, and so forms the Drop stone! Cool hey! So nobody likes a spoil sport, so imagine you're the neatly horizontally bedded Witteberg shales and all of a sudden the Dwyka comes along and drops a dropstone, now this dropstone is your problem... and what a problem it is...

Below we can see how a dropstone has deformed the Witteberg shales, I'm pretty sure it's Witteberg anyway.. Oh and F.Y.I this is my geo hammer I lost in Oudtshoorn... I even saved a waypoint for god sake, yet it was gone! So keep an eye out next time you're around Oudtshoorn!

Here's some more Peninsula Formation that wasn't spared the wrath of the glacier! This time it was during the time of the Pakhuis Formation deposition. This striations mark the bedding plane of this Peninsula bed, and note that this is now subvertical which means that this bed must have been deformed after the striations were formed. Rounded Quartz pebbles are common in the Peninsula Formation and often display these striations.

Dont worry though the Peninsula is a tough cookie, below next to the cool backpack and German school note book, you'll notice the sandstone dykes protruding through the overlying Pakhuis! There's always a catch as you know, and in this case it's no different... One has to wonder how did the sandstones manage to intrude up into the Pakhuis?? Well I have an idea and if you want to maybe try your luck, leave the answer in a comment or drop an email and we'll see what you got!

These Peninsula sandstone dykes mark the top of the Peninsula and the bottom of the Pakhuis

Here's a hint: The answer for above may be responsible for this: (Not Scott btw)

Being in Cape Town, far away from active glacial deposition there's not much else to look for, but below is the Sneeukop member of the Pakhuis, which is kinda marks the top. So whats different here, this is firstly not a tillite, but rather this has been more likely been deposited by the melting of ice. This process would have produce a type of slump type of deposit, viz a diamictite. It's quite characteristic in that it has just a massive texture with clasts of all sizes.

Finally! The famous Maclears beacon above Table Mountain, has been called Pakhuis for quite some time now, but is it really? Who knows, but the vast array of pebbles in these rocks have lead people to believe it to represent a type of diamictite, while some have also apparently found striated pebbles, anyway if somebody out there is feeling for a hike, go and check it out and let us know what you think!

Later... . . . .

Friday, June 6, 2008

So if you thought that last drought was bad, this one was insane!
Yes this blog is all but dead, so I'll attempt to revive it a bit!

Right now we've just completed the first string of honours exams and now preparing fro the long haul towards the end!

Along the way we've began our honours projects!

Scott has decided to try and solve the mysteries of the Cape Fold Belt! It's one of the big mysteries of this century and he'll be solving it in a couple of weeks from now! Isn't that cool?!

Here's Scott checking out some sheared granite. This is a highly felsic granite with alteration sericite giving it a green colour. This is really an uphill battle for Scott, but he'll do it, so make sure you get his journal article next year!

In the same time Nils has been roughing it out in ice cold conditions! Why so cold you ask?! Well because he will be finding out whether or not some deformational structures in the top of the Peninsula Formation has been caused by Glacier deposited Pakhuis!

Here's some of these chevron type folds!
So yes Nils will have his work cut out climbing up these precipitous cliffs all for the sake of geology!

Remember that when you're climbing up cliffs without the adequate climbing equipment your last will and testimony must be complete!

Sunday, July 8, 2007

wow we have had a bit of a post drought!! ive been very busy in the field so i have an excuse.

now to a bit of catch up... I said in a previous post that im currently working for a consultancy called Umvoto, based in Muizenberg, Cape Town. They basically specialize in anything to do with ground water or the environment in general.

ive been in the field for them twice so far and am going to head out to Oudtsoorn to help supervise some drilling. The first bit of field work involved a lot of 4x4ing (of which i previously had dangerously little experience) and trekking around the mountains pretty much avoiding paths of any kind. The reason for all this madness was to get water samples for a study on the brandvlei spring which surfaces near where we took the samples. the water comes out at like 40 degrees C which means it has circulated to a depth of a bout 2km DOWN! quite a way for the water to travel :) There is some kind of structural control on the spring.

anyway here are some pics

This pic is of one of the more timid parts of the 4x4 trails. im not lying when i say these trails were REALLY scary to drive on. Oh well, whatever doesn't kill you only makes you stronger :) This is especially the case in this example as i now have a rudimentary understanding of 4x4 driving :)

At this point in the trail we decided to walk :) i could definitely see us getting stuck!

Finally some of the views were really amazing
More info and pics on my experiences in Namaqualand and the ass crack of a town called kliprand :)

keep well

Tuesday, June 26, 2007

How to get samples from those... extreme places

Well, tis I... ZERO ;)
my thoughts are to be at the disposal of any geologist world wide and compliant I will be...

R.O.C.K.S. (Rarely Other Careers Key into Success)

Here's us gathering samples during a field trip...

First we need to get to the right place... what better way than...

Tag: Extreme rock-jumping

Method: Leap from peak to peak in fastest possible path. Putting yourself in prime position for sample gathering

Conclusion: Went well, except had to leave bag and clothes behind as got to hot (or should we say... extreme)

Next we get into sampling...

Tag: Extreme Sampling

Method: Buldging muscles and swing motion, using gravity as the primary force to retreive sample. Activation Energy produced by rapid horizontal bursts upon the sample, bringing transport in motion

Conclusion: ABORT, near fatal encounters: cuts and rolling persons instead of boulder.

Suggestions: Throw sample off top of cliff and retrieve at bottom...

Tag: extreme "Hauling"

Method: bear-like growl accompanied by violent jerks of arm to produce maximum distance

Conclusion: Had problems finding samples retrieved at peak and arm rendered useless for a couple hours...

Wednesday, June 20, 2007

thanx scott. i guess this is the only way of communicating with you guys either in thailand or doing hydrological things! btw i will be letting everybody know how to lose 6kg in 5 days if they want. so to keep the pics going, here's some weird fog coming in around table bay, it just looked strange so i thought i'd show you guys. note scotts giraffe working the docks.

and yes, a good way to spend the holidays is to study some geology for a phantom exam!

Monday, June 18, 2007

Hi everyone

well all the contributers of this blog are now finished exams! well except for one, Taufeeq had to keep to his extreme geology ways and so he got extremely ill during exams! i saw him a few days afterwards and he looked terrible! no offence man ;) So he still has to write one.

Another contributer is currently on a ship near Thailand looking at rocks from the bottom of the ocean! Jackie this is the only way i can think of communicating with you :) Post something about your experiences abroad!

Nils is tired of geology so hes been looking for a job at a restuarant. good luck man. Im doing an internship at a local hydrogeological consultancy called Umvoto. Today was my first day and well... i read a whole lot. things are looking up though. ill give a more detailed description of what my jobs entails once i know myself :)

scott out

Saturday, June 2, 2007

Okay this has nothing to do with geology but i still thought it was pretty cool. I helped Nils move a couch into his new flat. it was too big so we had to pull it up!! We tied the one end of the rope around a friends waist and he acted as an anchor, holding on to whatever he could!

This is me busting my gut to get this dam thing up to the balcony
After we finished pulling it up the first thing we did was sit down on it and drink a beer while gazing at Table Mountain. good times

If anyone needs helping moving a couch just get in touch :)