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www.niger-meteorite-recon.de
Rub' al-Khali Expedition 2008
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Text: Svend Buhl, Photos: Svend Buhl and Thomas Kurtz
For us however the day of turning back had dawned. Slowly
but surely we were running out of supplies. Our provisions of fuel
and drinking water were almost exhausted. We were worn out as well and the
daily tuna-date diet did not do much to improve our fitness. To our good humor
the worsening conditions however did no harm. We had reduced personal hygiene
to a necessary minimum, by other words, one shower per week had to do. One hot
noon I took the liberty to use
the exorbitant amount of half a liter of water for that purpose. In favor I
contracted my team mate's articulate disapproval.
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In front of the dark background provided by the meteorite the moving wind born sand can be seen
which is responsible for the effect of corrasion. The image was
shot during normal wind velocities of approximately 12 knots
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I found myself accused having feasted a 'bathing debauch' , also, I believe,
I repeatedly overheard the term 'deluxe camel' in that context. To demonstrate
how 'one takes a shower with 250 milliliters only'
Thomas went to the far side of the Land Cruiser, while I sat in the
lee of the car brewing up a tee and grinning like a Cheshire cat.
Improvidently Thomas had deposited his cloths on the roof
of the vehicle, from where the breeze shortly upon blew them off and down
in the sand. When some underpants landed next to the cooking pit I vociferously
bristled at suchlike 'amatory approaches', formally refused to tolerate such advances
in the future and made clear that by no means I would accept
'such excessive demoralization' in 'my camp'. He should put in his pipe and smoke
that this was an expedition 'with respectable moral integrity'.
Although I had achieved satisfaction for the 'bathing debauch' charges, the
episode provided occasion for a cheerful exchange of verbal blows that went
on for the rest of the day. On every occasion Thomas pictured me as an ecological
kamikaze and exorbitant waster of vitally important resources
while I in turn called him a voluptuous thug and to my personal security demanded a
considerable security distance between our tents.
By such disport in good humor we covered another one
hundred kilometers in southerly direction. Prospecting on the way
was not possible due to a high contamination of the ground with dark
rocks distributed throughout the area by ancient alluvial activity. Later
that day we passed a belt of wide stretching sickle dunes that forced us several
times to abandon our course and to take long detours. It was not until the late afternoon
that we found an area of deflation basins interrupted by shallow limestone ridges
that intersected them like honeycombs.
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Desert pavement or ‚mosaic' named ‚Serir' or ‚Rikh' in Arab. The scalecube is 1cm
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Here the desert pavement, named ‚Serir' or ‚Rikh' in Arab, had
developed an almost perfect distinctiveness. The array of the weathering
debris on the surface was of such an evenness and regularity like I had never
seen it before in other deserts. Like on a mosaic floor the stones lay arranged
close packed, with the flat sides which provided the least contact surface turned
upwards. The interstices filled with finer grit were often less than a centimeter wide.
The sight of the pavement like floor suggested great firmness, all the more it surprised that
one's foot sank in to a depth of three to four centimeters, because the pavement
covered a layer of loosely packed gravel and silt.
Surfaces like these are the result of a sorting process that
continued for millennia. Deflation and wind erosion of the finer grained
components of the top soil leaves only the coarser grained rocks to further
abrasion. If the original surface is composed of different grain sizes like
for example silt, pea gravel and smaller rocks the eolian deflation acts
selective. That means the fine grained material will be transported away first
while the larger components remain and erode further.
A soil horizon originating from such a sorting process
somewhen reaches a stable and inactive condition. Then
the transformation
almost comes to a halt. The smoothness of the face of the
desert pavement provides hardly any contact surface even at
high wind velocities.
In contrary the coarse grained Hammadah surfaces even
add to the eroding forces of the wind due to macro-turbulences
which increase deflation and the blowing out of
the silt components. In case of the 'Serir' or desert pavement,
the fine grained components remain under and between the mosaic cover.
All larger solid objects which came to rest in or on top of
the original top soil horizon during the deflation process
are found on top of the recent surface. This includes
prehistoric remains, modern artifacts as well as meteorites.
If the terrain is even they can be spotted over considerable distances.
With the field glass Thomas had discovered a couple of
molehill like features that we wanted to check. On approaching
we recognized that they were indeed the work of an animal. From the
entrance of a tunnel a specimen of the cape or desert hare (Lepus
Capensis) watched us suspiciously. This animal is distinctly smaller
than his European conspecific and is therefore frequently mistaken
for a coney that is not domestic on the Arabian Peninsula.
While Thomas fell into the habit of a Japanese tourist in front of the Eiffel Tower
and shot one photo after another I grabbed for
the Hensoldt binoculars to search the plain ahead of us. After I had
completed this I pushed for a swift departure because in only two hours
the sun would disappear and the day had remained without a find so far.
My team mate was however not nearly done with documenting the desert hare so
I got out of the car with the binoculars
to see if there was something interesting beyond our usual identification
range for meteorites. Perhaps at least a gazelle or a camel.
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The author battling with the right angle
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In doing so I could make out one, no two black dots closely
together almost against the sun. They were rather suspected than
actually to be seen. I had to rest the binoculars on the door
frame in order to get a stable image. I turned the dioptric calibration
once again to tweak the last out of the Hensoldt glass. 'Right, there you
go' I thought. In a distance of four hundred to five hundred meters they
were. But I could
focus as much as I wanted, I wasn't able to recognize more than two black dots.
This could be everything. Meteorites were the most unlikely.
‚Got something' I said climbing back in the car,
offering the binoculars to Thomas and not turning my head,
careful not to loose the direction out of sight. 'Two o' clock,
five degrees below horizon, very small, very black'. Thomas pushed
the dust goggles up to his forehead and silently watched through
the glass in the pointed direction. Finally, after a brief expert
glance towards the sun's position he declared, 'diagonally in the
backlight, probably the shadow of a stone or flint stone pebble. At
best a can. Would also explain
the second spot to the right'. His last comment referred to the old
truism that where one can is in the desert there is also a second.
‚Let's go there anyway and check' I suggested, but Thomas again
was lost in setting the aperture to catch the ultimate image of the
desert hare. Well, as mentioned earlier when Allah created time he
made plenty of it,
so I refrained from inappropriate haste and started not until
the motif was obviously exhausted respectively the memory card was full.
It would become the most exciting five hundred meters drive of the whole
tour. Although the unfavorable light prevented
a clear identification until we were only a stone's throw away from
the objects, we had already ruled out the can theory halfway.
When we stopped alongside our two targets we had driven a distance of exactly 520 meters from where
I had first spotted them. There on the Serir rested one of the most gorgeous meteorites that we had found so far.
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'Rub' al-Khali 022' (field name), a 408.50g chondrite
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We cheered like Emir Musa on sight of the City of
Brass and congratulated us mutually to the find.
Thomas insisted that his photo shooting with the desert
hare had been the initial key to our discovery. A point that made sense to me.
The meteorite had the size of a small fist with the approximate shape
of a pyramid with a trapezoid base. All lateral surfaces but one had
developed shallow but well defined regmaglypts. The conditions on the
sand free Serir surface had favored an exceptionally state of preservation. Due to the
lack of coarser grained wind borne particles the meteorite had only suffered
the impacts of finest grained silt dust particles.
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Side view of 'Rub' al-Khali 022' in situ
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This process had not led to corrasion and ablation of the mass
but to a smooth polish of the aerolite. In combination with desert
varnish producing organisms on its surface the meteorite had developed
a bronze colored satin luster under which the original velvet textured
fusion crust still showed trough. The under surface that had been in the soil if
only a few millimeters, displayed only minor signs of oxidation coating a
velvet rough and almost entirely preserved fusion crust.
A few paces away rested a second fragment of 110g that
fit seamless onto one flank of the main mass. Due to weathering
along a planar shock fracture it had sprung off the main mass and
by eolian and fluvial transportation over the millennia it had
been moved towards its recent position, seven meters from its mother body.
It was our second to last day in the desert and to
celebrate the occasion adequately we wrapped ourselves into
the traditional Arab dressings which we had brought. On the
crest of a hill nearby the find location we enjoy the
performance of a sunset in candy colors that not even Ridley Scott's
special effect artists would have been capable of conceiving.
At the next morning our course led us further southwards.
At noon our cell phones for the first time within the last
twelve days showed a weak connection
to a Saudi mobile network. Perhaps there was an oil camp close
by that was connected to the network along the asphalt road via a booster.
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Sunset light over the Serir
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Once again the area became sandier.
Around noon a couple of widespread groups of cans
kept us busy for two hours. Repeatedly they
deceived us by their coal black appearance and we had
to check every single one of them to make sure that no meteorite hided among them.
In the bizarre landscape the sandblasted tinny casings, half
sunken in the sediment, seemed like
the fossil mail links of an extinct species, washed ashore
the beaches of a cretaceous sea by some elaborate geological sorting process.
Two hours apart we found the fragments
of a heavier weathered meteorite. The second find
lay flat on the ground beside a 4wd track. It would have been
impossible to spot, had we not driven by two meters from where
it rested. In view of the outside temperatures of 113°F we indulged
ourselves a nap under the car. Several times dust devils whirled
through our camp. Afterwards we served ourselves a strong tea.
In an unwatched moment Thomas screaming orange
thermo mat took a life of its own and chased like a
flying carpet in a gust of wind off
into the distance. Due to the heat we possessed the approximate
reaction rate of a wandering dune and simply watch the incident dumbfounded.
Thomas jumped up first and chased his mat with giant leaps. I was
close behind him but had to abort the pursuit after a short time convulsed
with laughter. Because every time Thomas had just caught up with his mat
a fresh gust of wind lifted it up again like a treacherous demon and carried
it a hundred meters further. After a wild chase it finally got caught in
the thorny branches of an acacia from where Thomas freed it under curses that
would have made a Sudanese dervish blush. We turned back facing a sweaty
march towards our vehicle, that flickered through the heat
in the distance like a dinghy that drifted away while one enjoyed a brief swim
among the wave troughs of a malicious sea.
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'As-Schadschara wahiida', the solitary tree
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In the afternoon in the flickering haze
a single tree comes into sight. We change course because
it is the first and only tree we see during our whole stay in the inner desert.
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The umbrella acacia (Acacia tortilis) is one of more than 1,200 species of acacia. It
endures extreme droughts and survives sand storms as well as the damage afflicted by
feeding camels. Frost however will kill the tree
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It is a lonesome umbrella acacia (Acacia tortilis), vegetating a
life of hardships in the barren wasteland some eighty kilometers from the
next water hole. I tell Thomas about the 'Arbre du Ténéré', the Tree of the
Ténéré, a single tree near the unmarked 700 kilometer route from Agadez to
the salt oasis Bilma. This tree was also an umbrella acacia, about three meters
high and the only tree in a radius of 400 kilometers. It was considered the most
isolated tree on Earth. At least until 1973 when the tree was struck by a drunken
truck driver and died. This is the official
variant, other versions of the story report that a French tourist collided with the
tree when she mistook it for a mirage.
The Arbre du Ténéré was regarded the magic tree of the Tuareg and
served the Azelai, the annual great salt caravan as a landmark for more
than ten generations. Many legends entwine around it. On occasion of
digging a brackish water well at its foot in the winter of
1938/1939 a party of French civil engineers discovered that the roots of the
acacia reached the ground water in a depth of thirty six meters.
Despite the common lack of firewood in the Ténéré desert
no Tuareg would have dared to touch the wood of the tree or even
break a twig of it. After its death the Arbre du Ténéré was
transported to Niamey where the trunk is exhibited until present
in a gazebo that was built solely for this purpose. The
dendrochronological analysis produced an age of the tree of
more than three hundred years.
Following ancient custom every caravan donated a fraction
of their water to the Tree of the Ténéré, be it even
only a spoonful. In doing so the Tuareg expressed their
affection to and their solidarity with life in a hostile environment.
To this purpose one would dig a hole at the foot of the trunk
that was filled again after one had poured the water in.
This way there was a chance that some of the humidity reached
the capillary roots before the merciless sun would vaporize all of it.
Of course we proceeded after the ancient custom with the tree we had found as well.
To the asphalt track it was a mere seventy kilometers and even if we had to
cover this distance by foot in an emergence case, we could spare five liters of our
emergency reserve that currently contained forty liters without endangering us.
At night after long searching we found a few shallow hills among
them we pitched our tents. At the windward foot of a slope we dug a
wide hole in which we put the Marston Mat, the empty and airtight sealed
canisters and a couple of crates with canned tuna. Then we refilled the
hole. We intended to return and penetrate deeper into the northern dune
belt. The depot would wait for us - Inschallah. From our nightly bivouac
we stood and watched
the moving lights of the trucks, which we could see passing by in long intervals
on the asphalt road at the horizon.
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