Guest Post: The Pellaberg Traverse

Today’s post is a little campfire story from my friend Ben Melosh. Ben is a fellow Californian working here at McGill with Christie Rowe studying brecciation and earthquake processes. Check out his personal site HERE. Without further ado, here’s Ben.

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We broke camp late and headed toward the long ridge. Our basecamp was along the abandoned mine road that led to the boarder past the game camps of Pellaburg. Just the night before, deep ground-shaking footsteps had silenced us, stealing a toast from our lips. In the dark imagination surrounding our small fire, what could have been a Zebra turned into a Rhinoceros pounding over scree just out of sight. The local farm hands had told us there were no Rhinos here, just in the surrounding game parks where they were harried by rich American hunters. They said that the game parks were all fenced off.

By the time evening came again our packs were heavy, but not with food, our food was gone, our water low. We carried rocks now in their place, rocks that tell an ancient story of struggle in the deep earth. The sun was at the horizon throwing shadows behind every stone. We guessed at an hour of dusk and then an hour of dark to carry our burden back to the truck. This was not going to be a hike for people who like to talk about hiking. I looked at Louis. My field partners’ loaded pack slipped from his shoulder and he caught it on his broken arm as he set it down. He quietly repeated the word: “ouch”. You can learn a lot about a person in the bush; Louis was tough. We were going to make it back.

We headed north up the largest ridge, from there we would just have to hike the ridge top to the west until we cut again toward the north, dropping partway down the ridge to a saddle were we had set basecamp. Simple enough. The steepest part of the hike came first and was the easiest. The sunset cast long African rays through purple-blue clouds. We reached the ridge crest as the sky turned dark purple-gray and a lone quiver tree silhouetted black against the rising ecliptic. The moon was a sliver. We took a moment to enjoy our progress and drank our remaining water; on the map it was smooth sailing from here on out.
Louis’ long legs seemed to gracefully hover over each stone and bush as we stepped from dusk to dark. It took more and more time and effort to place each footstep. In the dark the sharp boulders and loose scree became indiscernible from the surrounding hill slope save for the halo of our headlamps. And we had somehow lost the ridge. I secretly hoped my pack was heavier than Louis’, as an excuse for slowly falling further behind. But I knew that my pack was not heavier; Louis was tougher. Side slopping westward in the total dark, we could barely make-out the faint hint of the ridge crest way above us to our left. To our right was a deep ravine. Blackness.
Then we spied it, a faint white-silver glimmer in the distance, much further below us and off to the northwest, it was the truck. We regrouped, and started to doubt ourselves, staring intently into the darkness where the faint and occasional glimmer would appear. It was in the correct direction, at about the correct distance and some of these hill slopes looked familiar. Plus we had been hiking for about two hours; figuring it must be the truck we started down.
When we hit the game fence we knew we were lost. There wasn’t supposed to be a fence, we had planned to backtrack our course of two days prior and we had never crossed a fence. Out here a fence means game park. It sunk in fast, we were on the wrong hill and that glimmer of white-silver hope in the distance was not the truck. We had no choice but to follow the fence back up, back up to the ridge we should never have left. When the fence crossed over a cliff we had no choice but to throw our packs and crawl under, into the game park. We continued our way toward the ridge in what we hoped was the final up hill push, the weight of our packs and our pace now the least of our concerns.
When we reached the ridge top we were tired, thirsty, and starting to get cold. The wind blew hard and our headlamps cast narrow beams and broad shadows behind the low shrubs on the lunar sand blown crest. When we laid down our packs I was worried we would not be able to lift them again, although the prospect of sleeping in the park was not appealing.
Then I remembered, of course, I had waypointed the truck with my GPS two days before. I had made a habit of doing this in previous years, just for this occasion, but had almost forgot when it mattered. I flipped through my notebook and fired up the handheld GPS unit. I could feel the relief lifting our shoulders.
With the GPS running it still took us about another hour before we knew we were close. When we finally cleared the last hill and turned north less than half a kilometer from the waypoint, we still could not see the truck. It was pitch black and clouds had blown over the sliver moon. The final descent to the truck was much steeper in the dark than we remembered. We could not see the truck until we were within 20 meters and her beautiful license plate shone back at us.
After collapsing into our bags in the haze before sleep I realized that although we had crossed into the game park, we never crossed out. Footsteps.
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Bomb-proof sample packing

Geologists travel near and far in search of rocks. We measure sedimentary bed dip, record structural data, and collect samples. Lots of samples. This summer during my Namibian field season I collected 70.3 kg of rock samples (which is considered a light load), some small some large. The geologist is then faced with the problem of getting the rocks back safely to our home institution. Partly this is running around town acquiring the necessary export and shipping permits. The other part is packing the samples to ship. Geologists all have their own methods. I would like to share mine. I was indocturated with the CRowe method of sample shipping.

Here we’ll be packing our samples in used paint buckets and securing them with a silicon foam.

Materials and Tools Needed

Materials:

  • Large paint buckets (used can be acquired for free or cheap. New is $$) with lids
  • Black heavy duty garbage bags
  • PU-Foam (silicon foam)
  • Duct-tape

Tools:

  • Hammer

How to pack your samples

I’m assuming you have already placed your samples in sample bags and written sample name, ect on the bag. I like to secure that bag with duct-tape to keep the samples from moving within its bag. 


  1. Place the sample in a black heavy duty garbage bag. Only the heavy duty black bags will work in the case. Lesser bags will be dissolved by the PU-Foam. Several smaller samples may be placed together in the same bag. I usually pack no more than three samples in the same trash bag. Close of this bag and wrap excess bag around itself. Place it in the bottom of the paint bucket. Repeat until you have a layer of rocks on the bottom of the bucket.

  2.  Shake shake shake that PU-Foam can. Install the applicator straw. Be very careful to not get any foam on you when packing samples. It’s hell to clean off. The only effective method of removal seems to be acetone. Some PU-Foam cans come with plastic gloves, but these can be annoying to use, so best just be careful. Apply the PU-Foam to gaps between the samples and the bucket wall. The foam will expand, but no reason not to apply liberally.

      

       

    1. Wait for the foam to set. The PU-Foam cans usually recommend waiting 2 hours or more. This is a tad long, but the more time the foam has to set before adding the next layer the better. If the foam is not allowed to set fully, it will morph into a sticky ooze. For this reason I will pack multiple buckets at the same time.

    2. Now that the layer has set. Repeat steps 1-3 until the bucket is full. Don’t forget to let the foam set between layers. Relax, have a beer while you wait.

    3. Now we’re going to seal up the bucket. Slap the lid on and use a hammer to bang down the lid’s side tabs. Be sure the lid is totally secure and doesn’t spin. Finish off the bucket by going around the lid with duct tape.

    How do you pack your samples for shipping? Is this too extreme? 

    Fugitive Geologists: The Sheltering Desert

    “If war comes, we’ll go to the desert”

    With the outbreak of World War II, the wheels of war were turning in Europe. Soon the frenzy would catch up to the colonies. In Windhoek, Namibia two German geologists were seeing more and more Germans being put in internment camps. Determined to not be locked away Henno Martin and Hermann Korn, with their dog, Otto, fled into the harsh Namib desert.

    For two years they lived brutal lives as bushmen, killing game for their food, seeking drinking water, and conducting geologic research and studying animal behavior in Kuisib Canyon. 
    A graphic autobiographical account of their time in the desert is told in the book “If War Comes, We’ll Go to the Desert” by Henno Martin, and in the English translation “Sheltering Desert”. 
    Henno Martin weaves fantastically detailed descriptions of their lives, including brutally honest hardships and the gory violence of living off the land, killing for your food. In one chapter Martin describes how he crippled and decapitated the leader of a baboon troop that was continually fouled their drinking water source. The water source wasn’t fouled again after. The book is incredibly violent at times, and is contrasted with philosophical chapters featuring lengthy discussions with Hermann about topics such as evolution, the human condition, and the behavior of the creatures around them. 
    Excerpts can be found here and here
    One morning before sunrise I was sitting up as usual when I heard the crunching of gravel followed by a loud smacking of wet chops. A horribly ugly hyena was at the pool. After drinking it licked its forepaws and then trotted off along the game track which led down the river bed. I was following it with my eyes when I noticed a leopard coming along the same track but from the other direction. The two animals came closer and neither gave any indication that it had spotted the other. The leopard’s fur was ruffled and it slunk forward like a big cat towards the hyena, whose high shoulders and great head with its enormous jaws made it the taller. The two animals were quite close to each other but still neither of them made any attempt to give way.
    When they were not more than five paces apart they both stopped and looked at each other for the first time, standing motionless for several seconds, apparently weighing each other up. Then the leopard gave a low growl, and at that the hyena turned sideways, backed off the game path and sat down on its haunches like a dog. The leopard then stalked past silently like a great lady after a short and triumphant exchange with a rival, going not towards the water, but up the northern side of the slope. The hyena sat there and watched its rival depart, and when the leopard was about two hundred metres away the hyena gave vent to its wounded feelings in a long drawn-out cackle. The leopard didn’t even bother to look round. The incident was grotesque, a caricature of human behaviour, and it struck me that the »all too human« behaviour of men was in reality »all too animal«.
    The 1958 English translation is available in the public domain from Internet-Archive. Get a pdf here. The photos did not scan well. There is also a newer edition available from TwoBooks, a German publishing company. This is the copy I own. I think whoever was doing the translation was also drinking as there are numerous typos here and there. This edition does however have amazing photographs. You can also find used copies of previous editions on Amazon and eBay. 
    This is a must-read for any geologist. Henno’s eye for detail and ability to share that detail is inspiring. I’d love to peak at his field notes. 
    See another description of this incredible story, along with some great photos of Kuisib Canyon HERE.

    All photos in this post are credited to Henno Martin and TwoBooks publishing

    Rock n Roll fault rocks: a pictorial journey aka my Namibian field season

    So my last post was a tiny tiny update. I should write more about what I’ve been up to the past month and a half. First off, this has been an incredible adventure. Namibia is amazing. This was my second time to Africa (South Africa and Namibia). I’m currently living in the Geo department flat at UCT. Thank you to the department staff, and Tanya and Jacq for helping Ben and I get settled.

    EDIT: Click any of the pictures below for a larger view!

    I know, I know, you want to see rocks. Bear with me. Let me give you some context.
    So where in Namibia was I? Where the hell is Namibia!?

    Let’s zoom in:
    -24.262224, 16.2432

    Naukluft Nappe Complex
    That’s about 200km South-Southeast of the capital city of Windhoek as the crow flies. 

    The Naukluft Nappe Complex is a thrust fault system associated with the Damara Orogen (~550Ma) that emplaced meta-sedimentary rocks in a roughly Southeast vergence on undeformed basin sediments. This area was originally studied by two German geologists, Henno Martin and Herrmann Korn, in the 1930s. These two geologists would later live two years in the Namib desert hiding (and mapping!) during World War 2 (blag post on that coming soon). They divided the complex into three different nappes, though more recent mapping has established five nappes. Korn and Martin also made the observation of a fault rock they describe as the “Unconformity Dolomite”. You know how geologists love to name stuff. First it was “Unconformity Dolomite”, then other authors called it “Lubricating Layer”, then other authors called it “Sole Dolomite”. From now on let’s agree to stick with the sole dolomite convention.

    Carrying on, this sole dolomite is the a layer of rock that separates the footwall sediments, blue limestone and shale, from the hanging wall, which is a charlie foxtrot of dolostone, quartzites, and shales. Want a photo of what this thrust looks like? Check out the header for this blog! Oh, you’re too lazy to scroll back up? Okay, here you go:

    Naukluft Thrust

    and at another location:

    Naukluft Thrust

    Did you spot the fault yet?

    I have so many pictures of this thing it is ridiculous. Tons of panorama shots too. Sadly, the GigaPan uploader can’t get through the UCT firewall, so we’re all going to have to wait until I’m back in Montreal to see those panoramas. It’ll be worth the wait. I’m getting ahead of myself.

    So what does this sole dolomite look like? It’s the brown-tan bed on the blue limestone in the above photos, but let’s move a little closer…

    Ben (Dr. Choff) for scale

    The limestone at the fault margin is mylonitized. Enough teasing, let’s look at the rock.

    Slicks!

    As you can see there is a foliated zone of dolomite at the fault surface. How about that rock above it though? That’s called “Gritty Dolomite.” It is a “cataclasite-like” fault rock that has dolomite phenocrysts, lithics, and silica. It looks like this:

    Gritty dolomite with silica banding.

    But sometimes it looks like this:

    Discrete gritty dolomite layer between sole dolomite (below) and a dolomite breccia (above).

    Or even this:

    Uhm, what? Laminated and folded (flow-folds?) gritty dolomite. Some silica banding.

    But sometimes it does this:

    Footwall limestone clasts in a gritty dolomite / sole dolomite breccia. A brown silica cortex surrounds footwall clasts.

    And how about up on the ridge (picture from this blog’s header and picture #2)… BAM!

    That is a RocknRoll breccia if I’ve ever seen one.

    Sometimes the gritty dolomite will inject upsection/downsection off of the fault, sometimes looking like this, often found with neocrystallized dolomite, sometimes doubly-terminating neocrystalline quartz on the surface:

    This rock is from part of a clastic gritty dolomite injection.

    And these photos are only on the eastern side of the nappe. Okay, okay, so WHAT were we doing out there? We were mapping this fault with a pair of these:

    Ben desires more satellites.

    The Trimble GeoXH. We set one up as a base station. The other is a rover. We walked the fault, making observations, taking measurements, ect. Once home I load the rover file with the corresponding base station file into the Trimble TerraSync software and presto! Centimeter GPS accuracy! As a first order question, I’ll be looking at how the geometry of the basal fault relates to the type of fault rock observed, injections, and make interpolations of the fault surface.

    In the eastern side of the Nappe typical fault dip is betwee 15-25 degrees, but varies widely. Now on the West side…

    Tsams Ost locality

    Can you spot the fault? Hmm… that looks a bit different. Typical fault dip here is ~3 degrees. The foot wall is typically blue shales, and there is no gritty dolomite to be found. We do observe the occasional footwall shale injecting up into sole dolomite…

    Footwall shale injecting up into sole dolomite.

    There’s also some fantastic folding in the hanging wall.

    Hanging wall folds.

    I feel like I could continue on and on posting pictures, so I’m going to force myself to stop. I’ll put up a gallery of photos on my Google+ page in the near future. I’m incredibly eager to get back to Montreal to look at the GPS data and start piecing this puzzle together.

    Special thanks to Ben Mapani for his invaluable assistance and advice. Thanks to Ben Melosh, Jodie Miller, Clint Isaacs, Rangers of Tsams Ost, and my advisor Christie Rowe. An extreme thank you goes out to the Naukluft 9 park staff for their generous hospitality and assisting with charging of our GPS batteries.

    Desert graffiti. 

    Ever wonder what a dolomitization front looks like?

    Since I haven’t posted anything in a while here’s a fun picture. This is a dolomitization front penetrating into interbedded limestone and shales. Click for a larger picture after reading the description below (it’s worth it, trust me!).

    Dolomitization front, Naukluft National Park, Namibia
    Where dolomite is absent shales are purple and limestone is generally creamy. Within the dolomite zone the limestones have been alterted to dolomite and the shales have been altered to a green color. Awesome chemical reactions!