Day 2 - Supercalifragilisticexpialidocious

Day 2

By: Mihlali, Jennifer and Matsie

Bright and early from Ermelo we headed down towards Vryheid to meet up with Nigel Hicks from the CGS Pietermaritzburg office. He would turn out to be a truly supercalifragilisticexpialidocious guide and we honestly think he would make a great lecturer (Just putting that out there). To the geology. The day was mainly about sedimentology and we started looking at the Vryheid Formation of the Karoo Supergroup. The impressive  railway cutting outcrop that Nigel showed us was deltaic in origin, showing planar bedding at the base indicative of the pro delta  and trough cross bedding near the top indicative of the delta- front. The Vryheid Formation is perhaps best known for coal; the seams occur in the distal delta plain, however, they were  not visible at this locality as the sediments had been eroded away.

We then got back on the road and made a quick stop along the way where we looked at an outcrop of the White Umfolozi Formation falling under the Pongola Supergroup. The outcrop was an exceptionally sheared and deformed quartzite, but the most interesting feature was the armored lapilli tuff. Nigel informed us that the lapilli tuff was formed during a volcanic eruption where the pyroclasts from the lapilli and the armour is the ash that covered the lapilli. The clear contact between these deposits and the overlying andesitic lava was thrown in for good measure at this exposure! Just for interest, the geology was first comprehensively described by P Matthews  in 1967 (The Pre-Karoo formations of the  White Umfolozi  inlier northern Natal) in the GSSA Transactions..

GOLD !!!! J J J

Denny Dalton Gold Mine No 22 : sorry to burst your bubble  but sadly the gold left in the area is not economically viable!  Back to the sedimentology. The gold is hosted by the conglomerates of the Singeni Formation still in the Pongola Supergroup, the conglomerate is known as the contact reef, existing as it does between the Agatha  and  Singeni  formations.

Midday and it was blazing hot and we were sweating like CRAZY! Nigel had one more stop to show us and oh what a stop it was. There was plenty to take in and again we gonna say that Nigel is supercalifragilisticexpialidocious as he took us across almost 3 billion years of geology in one human ‘step’!

According to the stratigraphy of South Africa the volcanics and quartzite of the Nsuza Group was deposited first and then followed the andesitc lava and siliclastics of the Mozaan Group;  these lithologies were affected by a clear normal fault. The tillites are not displaced at all (# current situation) so the fault pre-dated the Dwyka deposits.

We then saw the glacial striations showing a North to South flow directions, plus other the glacial features including well preserved rock flour ,a nail head indentation,  and an Eskia (conglowerate at front of the melting glacier) – now that was a new one for us guys! Can’t wait for tomorrow!