Day 14 (Tuesday Sept. 19th )
To the Karoo, the P/T boundary, and the Rubidge Farm!
Making an early start out of Kimberly, we traversed a network of small (but
paved) country roads through the Karoo desert towards the small town of
Middleberg. The geology of the Karoo is FLAT, FLAT, FLAT, with scattered
mesas
capped by dolerite sills off in the distance. Farms, after widely-separated
farmhouses dot the horizon. Noah Nhleao (the Swazi geologist who is traveling
with us to Pasadena to use the paleomag lab) notes that many of the small
towns in this area actively excluded all blacks during the Apartheid era, not
even allowing domestic servants to live or work there. So we drove through
the
area, not bothering to give them much of our business. On the horizon we
see a
storm front approaching.
The first major geology stop was at Carlton Flats north of Middleberg, where
the Permian/Triassic boundary is exposed along a railroad cut in the greenish
and reddish mudstones of the Beaufort Group. This is the worst extinction
event in earth history, when some weird disaster pumped up the CO2 levels in
the atmosphere to the point where many, many things died. The sediments here
nicely record the change from gentle, vegetation-rich meandering streams of
the
late Permian to the barren, reddish braided streams of the early Triassic.
The
wind and rain drive us to take shelter in a train tunnel, amplifying the
mystery of the mass extinction event.
We then continue Southeast of Middleberg, on route N9 towards Graaf-Reinet. We
are warned that Lootsberg Pass, the South African type section for the
Permian/Triassic boundary might be closed due to snow, so it is urgent that we
make it before it is closed. As we drive up to the summit, we are greeted by
a dusting of fresh snow on the peaks on either side, but the road is OK.
As we
crest the summit, the setting sun hits the rain and falling snow at just the
proper angle for a 180 degree Rainbow Arc, one of the prettiest sights on the
trip. Despite the wind and rain, we take a 30 minute break to hunt for fossil
mammal-like reptiles (Lystrosaurus), which were the only group of ancestral
mammals to survive the extinction event. Eagle-Eye Curtis finds the best of
these treasures, with many rib bones and tusks preserved. Wildly enthused at
their success at hunting the bones of our distant ancestors, the gang decides
to return the following morning for more.
For this evening, we made arrangements to stay at a small B&B run by Robert
and
Mirriam Rubidge on their ancestral sheep-ranching farm, 'Wellwood'. Bruce
Rubidge, the brother of Robert, is a professor of Vertebrate Paleontology at
the University of the Witswatersrand in Johannesberg, and a collaborator of
JLK's on a NSF grant. The family has along history of interest in the
vertebrate fossils of the Karoo. Their grandfather, Sidney Rubidge, was a
good
friend of Robert Broom, the paleontologist who made many of the most important
hominid discoveries at Sterkfontein and Kromdraai mentioned earlier. The
family story goes that Sidney went out on a picnic with his daughter and
discovered by chance a magnificant reptilian skull with ferocious teeth.
Broom
was called in to look at it, and was wildly excited about the discovery. When
he told Sidney that it was hundreds of millions of years old, the Elder
Rubidge
decided that, if it had been on their family farm for that long, that it
should
remain there! Broom did the fomral scientific description of the skull,
naming
the beast Dinogorgon rubidgei (which is, by the way, featured in an article in
the September 2000 issue of National Geographic). The Rubidge farm and the
surrounding area proved to be a rich fossil collecting ground, and over the
years Broom and Sidney agreed to split the collections, housing some at the
Wellwood farm and others at various museums.
We had another wonderful South African braii for dinner, featuring tender
lambchops from Wellwood and other traditional puddings and treats. Although
the Rubidge B&B had only 8 beds, this was no problem for the intrepid gang of
Caltech GPS students with sleeping bags in hand.
Written by JLK
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