Sampling Waters in the Naukluft

For an arid environment, there sure was a lot of water around. Apparently there has been a lot more rain than usual; that is why the area was greener and buggier than anyone had seen in recent memory.

Water resource characterization is actually the main motivator behind this whole effort; my nominal (and periferal) role is to determine what role (if any) ancient or recent faults and fractures are playing in water exchange between the surface and the subsurface.

Most of the water resource extraction in the Naukluft Mountains, and pretty much all of it on the surrounding farms, is accomplished by "borehole". Many have a real working windmills - These usually pump directly into troughs for herd animals (and wild animals) to access.

Although these are often the easiest source for ground water samples, there are a few issues with them. For one, the boreholes are usually lined with some kind of pipe - usually metal - this will affect the geochemistry of the water if it sits in the well a while. Second, they are drawing all the time (whenever the wind blows). This helps with the first concern, as it means water doesn't reside in the borehole too long. However, it means the water level in the borehole might not be in equillibrium with the water level in the surrounding formation - and we want to know the water level of the regional/local water table. If the windmill pumps water out of the well, it takes some time for the water to flow from the rock formations back into the bore holeand during this time, the water level we measure will be too low. This ranger at Zais helped us open the cap under the windmill so we could drop the water level meter down.
We found a few boreholes, such as this one, which had solar panels apparently to drive pumps. This one looked like it was installed to keep a shower ready to go at this outpost on Die Walle farm. Alet is checking the shower tank for water... empty. Kate is getting ready to check the borehole for water... sealed.
The coolest samples come from the rock springs and seeps. Here's Kate suspended by her toes on a slippery algae-covered cliff wall, catching tiny drops of water as they emerge from the rock. We also sampled the surface water such as the stream Kate is trying not to fall into - this will all give a picture of what underground water looks like, what surface water looks like, and how the streams are fed during the dry season... Due to the high visibility of travelling thunder storms, Jodie and the students were able to chase down a few and collect several samples of rain water as it fell out of the sky... this is a great data point to have because it will tell us what the water looks like when it enters the Naukluft. I wish I had a picture of Jodie in a sudden deluge, holding a giant green bucket to shield her head from the huge rain droplets... so pleased with her cold rain sample... but as I was watching from the warmth of the dry bakkie the photos look like a rainy sheet of wet window. hm.

I have to say, Kate was really the workhorse of the water sampling team. She climbed walls and dove to the bottom of clear spring pools. Here she is after sampling the spring-fed creek in Waterkloof. You can see the wall of tufa behind her - more on the tufa deposits in a future post. Anyway it suggests that both surface and groundwater flow through Waterkloof were much greater in the past than today. How far back is the past? We don't know.
Here's Ben in the gorge at Die Walle, entertained by the struggling students climbing the walls to capture tiny drips of water! Behind him in the cliff you can see the reason for this canyon's name, Die Walle: the falls. Standing under that wall, you could see shoots of droplets literally spraying a meter or more out from the wall in the blackened area. A big pool at the bottom feeds the creek running out of the gorge.



We tested the water onsite for dissolved oxygen, pH, temperature, conductivity, eH, and total dissolved solids... Kate and Chris Harris have already started isolating the CO2 dissolved in the water to look at the carbon and oxygen isotopes. She will also analyse the water molecules themselves for hydrogen isotopes. She will also look at the isotope signatures of the rocks in the area, and the carbonate rocks that precipitate in these waters...These will hopefully be able to tell her about the chemical interaction between rocks and water, and possibly help trace the pathways by determining which rocks have more contact with water before it flows to seeps or springs.

Shane and Alet at U. Stellenbosch will find out about those total dissolved solids - what are they? What cations and anions are present, and do they come from rocks, from the rain itself, from biological processes, or human pollution? Does the water get saltier as it flows underneath the ground from the mountains out toward the plane, and the farmers there with their bigger ranches and multiple boreholes?

Pride from U.Nam will be putting it all together, as they say, he will be using MODFLOW to build a 3D picture of the Naukluft groundwater in space and in chemistry.

The big questions we all will work on together:
- If the farmers say some springs are drying up, is that due to over use of a static reservior? Or is there something fundamentally changing in the water system of the Naukluft?
- From raindrop to tap, how does the water evolve and change in chemistry? Is it always safe for humans and animals to use? if the water regime of the area is changing, will this affect the chemistry and safety of the water, as well as quantity?
- How much new water demand can the system support?
- Why are the rocks so damn cool?
Thank you.

The Sole Dolomite (SOUL; DO LO MITE!)

Yah, um, non-geologists might want to take me off your bookmark list for a little while. I think that leaves only testy trifarina to read my blog. Sorry mom, people pictures coming up here at some point! Anyway,

"THE NAUKLUFT" is a big beautiful nappe complex - a klippe on the plains, west of the highlands of Namibia - the last erosional remnant of a mountain range half a million years old. The rocks are even older than that. They are thrusted on top of each other - like a deck of cards spread out on a table and swept into a stack by a southward-moving hand. At the base of the stack is the master fault, along which the rock layers slid, according to previous estimates, something like 50-80km from their place of origin.

This master fault can be seen for miles around the Naukluft - it cuts a sharp, continuous swath across an otherwise convoluted terrane. It's easy to pick out the strange, massive, yellow dolomitic fault rock. Here you see the yellow "sole dolomite" crosscutting the footwall rocks of the Nama Group (gray-blue limestones) and layered brown carbonates of the hanging wall Damara group.

Here's Jodie and Pride on top of the sole dolomite - it has nice sharp contacts top and bottom. In many ways, this fault would be a simple case to study - if the fault rock wasn't made of dolomite (CaMg(CO3)2). Dolomite is maybe the weirdest common mineral there is. Old marine rocks are often made of dolomite - but modern ones pretty much never are. So the theory goes that limestones (CaCO3) which form in the ocean can be altered to dolomite by Mg-rich sea water. Only nobody's been able to make this happen in the lab - so the how/where/why part of the story is still an open question...

Here's an example of a meta-evaporite deposit - a place where dolomite HAS been observed to form in modern environments. Evaporites are salt layers formed when water evaporates (duh) - such as in saline basins in the western US. In the past when the Straits of Gibraltar have been closed by the northward motion of Africa, huge thick layers of salt have been deposited in the Mediterranean sea. This example is from the Nama Group, under the master fault. So a first order question - were these dolomites eroded by fault motion, and ground up to make the sole dolomite? Those white blebs are albite pseudomorphed after evaporite minerals - really cool.
Answer: Um, maybe. probably not. Meta-evaporites are a pretty rare component of those footwall rocks. Ordinary marine dolomites are pretty common in the hanging wall. But either way, there is plenty of ordinary dolomite around... to find its way into the fault zone. One standing hypothesis is that when the nappe complex was moving south, it traveled over the top of a modern (at that time) evaporite basin, and the mineral salts injected like a slurry into the fault. I don't feel too comfy with this hypothesis. For one - evaporites have a lot of minerals in them that aren't dolomite - and the quantity of those minerals reported in the Sole Dolomite by the proposers of this idea is ... a lot different... than what some more recent studies have found. For another... I suspect that if somebody took a closer, more quantitative look at the depth of the fault, the behaviour of slurries, and the deformation of the footwall rocks ... one might find that this is kinematically impossible. But, I confess, I haven't done this.... yet.

The sole dolomite has two main parts - either one might be absent at any given point - but basically there is the "massive dolomite" and the "gritty dolomite". The massive is just that - a slab of crystalline dolomite. No clasts, no banding, no bedding, no structures of any note. Literally featureless. Except for one teeny tiny planar vein of silica that Ben found - and helped me sample - at the Lemeonputz section, which is incidentally, the site of reintroduction of rhinos to the Naukluft Park. The gritty dolomite is composed of amazingly spherical, smooth rounded clasts - of dolomite, mostly, and bits of other things (granites, quartzites, evaporites, etc). Both were once thought to be sedimentary layers, when the thrust faults were thought to be gravity slumps (dip be damned!) back in the 50s-60s when a German group did some structural mapping in the area. Here's Jodie, pointing out the massive dolomite (beige, level of Jodie's head) and the gritty (yellow, where Jodie is pointing). The gritty dolomite crosscuts earlier mylonitic fabrics in the uppermost footwall, as you can see here at the "type locality" outcrop, and yes I got that sample!


There are some amazing features in the gritty dolomite... which i and some of the previous workers believe to be a fluidized cataclasite (regardless of how the dolomite itself was introduced into the fault zone!). Very thin, delicate veins are sharply cut by microfaults... these must also cut the gritty matrix, but they are often invisible away from the veins! This is reminiscent of some features we have seen at Pasagshak Point, Kodiak... which we also didn't make much sense of but I will ask some of the team if they have done any more work on it...

Suspended in the gritty dolomite matrix are large clasts - both of recycled gritty matrix, and also of "massive crystalline" fault dolomite. This one is wrapped or coated in some dense hard mineral - maybe silica? I will be able to tell when I get my thin sections made, when I get my rocks from Jodie, when they are cleared to cross the border... Do you know how many permits and stamps and things you need to move rocks across borders in Africa! I swear they're the only things that can't cross.

As if we needed proof of granular origin and high fluid pressures: gritty dolomite injection features, 12m below the fault in the footwall limestones. So. Gorgeous.



So much more to do here, more to talk about... need to go back to the Naukluft! More geology posts ahead.

New Students & Old Rocks

A couple weeks ago (before that trip to Namibia) I checked out the department's SUV for the weekend and we went on a "recce" (that's a reconnaissance trip) to check out some areas in the Cape Fold belt where two of my Honours students will be working for their theses this year. The two projects are really interesting and both capitalize on areas where there has been some research done in the past, but a structural approach could potentially give a lot of new insight.

We started at Pakhuis Pass, near Clanwilliam - the type section for the Ord/Dev. Pakhuis Formation. The Pakhuis Formation is a periglacial marine deposit (mostly, although there is some facies variation) which overlies the voluminous Peninsula Fm. sandstones which make up Table Mountain. At that time, our corner of Gondwana was at a latitude of about 70°S - a good place to make lots of ice and heavy d18O in the oceans confirms that this was a icey time on southern earth. The upper part of the sandstone, below the Pakhuis, has some folds & deformed bits - this could be due to drag from glaciers running over it, or to loading/soft sediment deformation from burial by the Pakhuis Fm., or by later folding during the Cape Fold belt orogeny. Here's an example of some sedimentary deformation, overturning of crossbeds:

The top of the Peninsula sandstones, at Pakhuis Pass, is a striated and compacted surface. Here are Nils and Scott in front of it. This surface is a disconformity and I could be convinced that it was striated by the passage of ice... although the overlying Pakhuis here is most likely fluvial...

This was Sila's first adventure in geotourism. He seemed to enjoy the driving, the scenery, the tour-de-force of the northern limb of the Cape Fold belt. How did he entertain himself when the rest of us took a while checking out the rocks? See for yourself:

We went south to Hottentots Holland nature preserve.... this is way "downstream" with respect to the Ordovician-Devonian paleo basin. This is also the location of the famous kloofing route through Suicide Gorge - kloofing is somewhat akin to what we used to call creek walking, with the addition of "compulsory jumps" - that is, over waterfalls which you can't avoid due to the steep canyon walls - so it is generally done only in the downstream direction. Suicide Gorge gets its name from it's unusually high compulsory jump: 15m.
In this photo you can see some sandstones in the ridge on the right - that's the Peninsula Fm. with the Pakhuis Fm. on top of it. The smooth green area in the saddle is the Cederberg shale, and overlying that, on the left, the Nardouw group sandstones. Here (and elsewhere) there is a localized fold zone at the base of the Nardouw sandstones! This has to be related to the Cape folding... since the folds are cylindrical, coaxial, sometimes kink folds... etc... they are clearly a tectonic feature. So why are they concentrated at this area in the section?

Here's all the boys on top of the Pakhuis Formation. Here, as in most of the area south of Pakhuis Pass, it's represented only by the Sneeukop Member which is a gritty, sandy, massive diamictite with randomly distributed quartzite pebbles - some of which are faceted/striated. Recent work has interpreted this as a glaciomarine diamictite - possibly sub-floating-ice shelf environment. Could be! It's not too thick (a few meters) and is regionally continuous for 10s-100s km. At Sneeukop (why did I take no photos?) it is involved in the upper-Peninsula deformation. Could this be giant load casts? Nils? take it from here. You're gonna need a nice compass and a lot of patience.
Here's a sandstone dike in the diamictite - derived from the underlying Peninsula sandstones. These are everywhere. They seem to have a preferred orientation. They have nice margin-parallel layering. They are apparently identical to the diamictite in grain size distribution (excepting the pebbles!). Paleoseismites? Catastrophic loading by the deposition of the diamictite? We may never know.


Oblique view of the diamictite bed.... very strange very cool concentric curviplanar banding features! Possibly oxidation bands - they are pinkish. Totally absent in neighboring units. Unclear how they relate to the joints which are now present.... another mystery.


to be continued...

Scenes from the Naukluft

In no particular order:

1. sunrise, looking west you can see the thin line of red along the horizon which is the edge of the Namib sand sea:
2. shady respite from the sun in waterkloof:
3. social weaverbirds
4. thunderstorm moving across the plain
5. butterflies everywhere
6. big sky and fluffy clouds, Naukluft mountains on the horizon
7. little boy watches as his father opens the well for us at Zais farm8. donkey carts are primary transportation for many Nama people
9. gray limestone: footwall. yellow blocky dolomite: fault rock.
10. springbok along the road

more details to come later...

Daan Viljoen Game Reserve

Jodie and I took a little break to drive 20km out of Windhoek to the Daan Viljoen Game Reserve. We saw an incredible amount of wild life in only an hour in the park. Here's the entrance gate.

We parked at the lodge in the park and decided to do a 3-km trail because that's all we had time for. We immediately walked into a troop of Chacma baboons. They look quite a bit different than the ones at Cape Point, larger and darker and... not tame. They did not hear us coming and the troup had quite a few young ones, spread around all over the hill picking something to eat off the ground - maybe grubs of some kind? A female gave the alarm when she saw us and a big male immediately moved between our path and the females. He gave us some warning barks and swaggered toward us on his knuckles like a gorilla. We just slowly kept on the path and once our intention was clear, the troup ignored us.

Only literally two minutes after we passed the baboon, we almost walked into this beautiful kudu doe. She was standing dead still behind a tree and we almost didn't see her. You can see she is quite a substantial animal, bigger than a deer and smaller than a caribou. Whatever that means.

No sooner did Jodie say "One rarely sees only one kudu" than we saw the males catching up behind her. They are much bigger and the curve of their horns tells you how old they are. They make 360° at about 2 years of age and 720° by about 6 years.


Across the valley we spotted some oryx (gemsbok) on a hill and on the way out I was able to get a photo:

The best treat on the way out of the park was this wildebeest right on the road. Look at his mane blowing in the wind. No really, click the picture. Experience the beest.

Friendly Windhoek, Namibia

Windhoek is a beautiful and friendly place! It's up at high altitude but with rolling hills and canyons around it, rather like being up on the Colorado Plateau. Jodie and I flew up on Monday morning with a very full "to do" list to accomplish before our return on Tuesday night. The airport is really cute:
Taxidermy services are available to and from the airport. This advertisement board reminds me of a certain children's book we used to have.

Coming into town, it feels a bit like a very small Salt Lake City, surrounded by... something more like Borrego Springs. Salty desert backwater with a life of its own! (Note that the blue at the top of this photo is from the windshield of the car).
Lunch, yum. Actually I had some grilled calamari and veg. Of course, the veg was grilled cucumber.
The Gibeon Meteorite Shower scattered these great hunks of Fe-Ni in the desert, actually pretty near the area where we will be working. It was probably one big meteorite that entered the atmosphere and broke up before impact - pieces are still being discovered. Indigenous people without a source of mineable metals learned to fashion spear points from the meteorite chunks and there is a rich archaeology of metalworking in the area. Some of the pieces are on display in this square in downtown Windhoek:
The University of Namibia is on a beautiful campus on the outskirts of Windhoek. It feels a bit like Sonoma State, only a lot smaller - relatively new buildings, growing feeling, like a community college back home only all the students are young and going somewhere! They are also perhaps the most beautiful people I have ever seen. Why are Namibians so beautiful? Healthy, slender, smiling. Anyway, I digress.
The young geology department has only (I think) 4 on the teaching staff - Ben, head of department and Jack of all Geological Trades is our co-Principal Investigator on the project. Another lecturer, Pride, was a hydrogeologist in Zim before coming to work at UNam and will be enrolling for PhD at Stellenbosch under Jodie's supervision - although I don't think he'll need too much! Their department space is in a corner wrested from the art department, and their teaching lab feels like it might have been a dance studio. Here's a blurry Ben and a semi-focussed stromatolitic chalk:
Here's Ben and the department "person who does/knows everything" (is there an official term for this indispensable person?), Joanna, and the amazing lab space:

Windhoek is a navigable and friendly city. Everyone smiling. It is relaxed but not slow. We visited the Geological Survey, the Department of Lands, and the Department of Water Affairs and in each case, got what we came for and went on our way. Having done such milk runs through various levels of government offices all over the San Francisco area, I can readily say that Namibian governmental services puts America to shame. And don't even get me started comparing to South Africa!

Next post.... animals.

Good book and new adventure

When scrounging the bowels of the library the other day in search of the Proceedings of the Geological Society of Poland, 1966 (no, we don't have it), I impulse-checked out an autobiography of a lady physicist, Fay Ajzenberg-Selove. Usually I would think that an autobiography of any physicist, lady or otherwise, would be like watching for mesons with a magnifying glass (ha ha) but perhaps my latent obsession with Dick Feynman drove me to check it out.

A Matter of Choices: Memoirs of a Female Physicist grabbed my attention right away because Fay is direct, candid, and funny. The title seemed to imply that she made choices, I thought sacrifices, and I expected there to be some regrets. It turns out Fay is not a regretful person! Which may be the best lesson to take from the book, for female physicists and everybody else. The story of how her family escaped the Holocaust is alone enough to make this a worthwhile read. Her underdog success, aided by a few gender-blind mentors and colleagues, was enough to warm my cynic's heart. She also takes a few institutions to task, by name (Harvard, Princeton) and points out the second glass ceiling at the tenure review. It was gratifying to google her and see that her website at UPenn is still active, as she is no doubt still active, even after surviving cancer and her husband's health problems as well. Fay's voice is objective, awkwardly literal (as physicist types can be!) and she tells the story of her life without sugar coating, pointing out when her recollections might have been bitter and assessing whether she still holds that bitterness. I think anyone reading this book would come away with a deep respect for the perseverance of a woman who quietly found a way to do what she wanted to do, without tooting her own horn, and truly picked her battles. While on some level an inspirational story, it was also a reminder for me of how much patience is required to break through barriers on ones own. Cheers Fay, and thanks.

Amazon link for A Matter of Choices

I'm off to Windhoek in the morning for a meeting with our new research group - no idea what to expect there, but excited! Sila asked for a souvenir - he wants a snow globe.

First day of school

Yesterday, this was my coffee cart. Mine alone.

Salsa Fresca will Find a Way

Look, I know you might get bored with the garden posts (mom) but for some reason I am SO INTO my little potted garden these days. It just blows me away that I can put water on something and food comes out. Way better (although slower) than Top Ramen. My mother-in-law told me this and it took too long to sink in. Her garden mastery passed away with her on 10 February 2007. If there's an afterlife, I hope she's enjoying the irony of watching me google "rosemary yellow leave edge lower water". Miss you Sue.

I have a total of 110 green tomatoes on 12 plants. I know this because I thoroughly tabulate tomato and flower counts by plant at 6 day intervals.

#111: I have the first evidence of Salsa Fresca to come...

It will be a HOT salsa fresca:

Paul brought us a lemon tree - although I hesitate to use the word "tree" because at 2m tall, it had exactly 3.5 leaves and enough catapillar eggs to insure that it would soon bottom out at 2 leaves! It was potted in a brick of sticky clay and no water or fertilizer seemed to affect it. We finally dumped out the pot, rinsed out the (tiny) rootball and put it in sandy potting soil, watered heavily, crossed fingers. A week later, leaflets all over:

and this morning, tiny pink buds. A valentines present

Weird to be White?

I have avoided discussing race too much on this blog, for PC purposes. It is a factor of life here but having gotten used to the particular tensions in the particular places and faces that I see every day, I think less about it now. It becomes very acute when I leave the city, because the areas that I go in the city are almost entirely historically "white" districts. I can expect to see people that look like me and have similar income levels. They will, however, immediately know I am a foreigner before I open my mouth. I think I am too unfashionable to be mistaken for Capetonian.

I got an email from a very good, very short friend who shall not be named at this point, from a hotel in Nairobi. This friend has just spent several weeks in rural eastern Kenya for scientific purposes. This friend wrote of a white hotel guest being a rude bastard for not being served dinner after kitchen closing, in spite of the fact that the city is in a state of chaos. My friend writes,

"does it ever get less weird to be white in an african country? these types of bougey establishments make me so uncomfortable. "

I have wondered the same thing. I am often embarrassed when I see white people being rude. Likewise, I am embarrassed when non-whites expect me to act like the rude white people. Race is a huge factor here, much because whiteness is still highly correlated with richness. Right now rich black people have arguably the same effect on the poor black majority as rich white people do, but their existence means something very different to that majority. And it's only the left-leaning people trying to point this out, especially the white academic ones who insist that ultimately it's class warfare behind all these problems. Although I think I agree with that in a broad sense, alarms go off every time white people try to move the focus off racism. Is that the legacy of the PC police? or is it because everyone knows that everybody else is at least a little bit racist, whether consciously or not?

There are way too many issues to address in one post, but the one I want to address is the one my friend wrote about, that is, the discomfort. Now, I am not talking about discomfort in direct interactions between people of different race, rather about the discomfort in witnessing or being obliquely involved in some types of interactions. This type of discomfort derives from monolithic treatment of racial groups, by people either within or without the racial group in question. Some of the things that are going on among people of all races, that when combined with a gradient of power or control, are the source of institutional racism.

Whites in this country are being called to task for their racist views, which have caused so much damage which will take generations to heal. Non-whites in this country have not had a systematic exhumation of their racial views and there are a lot of issues there. But through the process of "transformation" - which refers to institutional as well as personal change - there is a dialog developing about morality, humanity, and social organization that is helping people examine themselves openly and not from a place of shame.

If I sound weirdly happy about this it's because I had a great experience this morning in Employment Equity Representative training. Not because the training was so good (though it was), but because the group of people around me is so passionate about moving South Africa into a better future, and doing it RIGHT, urgently but not so urgently that it is done wrong. I am often reminded that in spite of everything wrong with this country (and there is A LOT WRONG with this country), the engine of civil expression and civil participation is alive and well.

Stapelia blooms and it smells like crap.

It is pretty but my office smells like.... um.... poopy. So I opened both windows and this set the door to rattling which caused JR to bust in this morning, thinking I had left the windows open over the weekend. He hates the rattle of my door. But why does he have a key to my office? That's what I'd like to know.