"Lambs to the Slaughter" Field School group of 2014: from left to right: Taufeeq, Khaya, Haajierah, Nick, Ndidi, Tebogo, Nox, Belinda, Penester, Eveline, Neo, Olma, Ntsundeni, Shane, Conrad, Mpumelelo
The CGS Field School of 2014 officially began today! The
team departed promptly (a few hours late) from the Council for Geoscience head
office (Silverton, Pretoria). The route began on the N4 highway crossing vast
sediments of the Pretoria Group (Transvaal Supergroup), before entering an expansive landscape dominated by the Permian Karoo Madzaringwe Formation. The highly
prospective coal seams within this unit are evident with various coal mines
along this route and moreover, the large coal-fired power plants, most notably
around Emalahleni (Witbank). It is worth noting here that coal powers more than
85 % of South African electricity and forms a key export commodity. Some of
this will be further discussed tomorrow, as the group enters the central Karoo
Basin, where discussions will also include the highly contentious shale gas
issue.
Neo couldn't believe that you can find stromatolites that are bigger than him
Before entering Nelspruit (Mbombela), the team followed a slight and
tremendously scenic detour toward Sabie and viewed spectacular giant stromatolites
within the Malmani dolomites. These ca. 2.75 Ga stromatolites display some of
the earliest evidence of life on Earth, where cyanobacteria in a shallow marine
environment slowly produced oxygen through processes highly similar to modern
day photosynthesis. Chert and ferrigunous layers are closely associated with
these giant stromatolites, what could this tell us about early Earth processes?
Modern day stromatolites can be seen along Shark Bay, Australia (http://www.sharkbay.org/stromatolites.aspx).
Interestingly enough, while these rocks host some of the earliest forms of
life, they also host some of the earliest signs of human life, inhabited in the
nearby Sudwala Caves (http://www.sudwalacaves.com/).
Barberton Mountain Land
The team then continued further into the past and entered
the Archean! The trip from near Sabie to Nelspruit forms a much quicker and
more efficient way of time-travel, than having to defy relativity and attempt
to construct a time machine. This change is marked by a drastic change of
scenery, from the enchanted forests of the Malmani, to the colossal boulders of
the Nelspruit and Kaap Valley Tonalite batholiths. To unwind and understand the
stories of the past, the team began the recently opened Barberton Makhonjwa Geotrail (http://www.geotrail.co.za/). The
Barberton mountain lands is one of the most well preserved fragments of early
crust and speaks volumes of how the early Earth would have been and functioned.
The Geotrail now offers visitors, both geologist and non-geologist a special
chance to learn about this period of the Earth’s history.
From left to right: Spectacular slump folding in ferruginous sediments; Conrad explaining paleocurrent direction in the white tidal sediments; Geological explanations handed to you on a plate...we break the interns in gently! (Watch this space for the real world once we hit the Richtersveld!)
Along the Geotrail the team was treated to a brilliantly
designed outdoor museum that perfectly illustrates everything that’s special about
Barberton and why this is one of South Africa’s most valuable piece of
geological heritage. This begins and ends with various types of volcanic rock
found within the ca. 3.4 Ga Onverwacht Group. This includes pillow lavas,
lapilli tuffs and komatiites. What do these rocks tell us about the conditions
of early Earth? Impressive banded iron formation outcrops of the Fig Tree and various
sediments of the Moodies Group was also seen, including some of the earliest
tidal sediments.
Top: Typical Barberton Makhonjwa Geotrail information board, lower left: Olma excited to observe pillow lavas that are twice her size, lower right: group, maintaining health and safety regulations, observe the white tidal sediments
Download the full route here (kml): Field School Day 1, the trip continues through Kwa-Zulu Natal and the Free State tomorrow!
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