PALAEONTOLOGICAL HERITAGE STUDY: COMBINED DESKTOP AND FIELD-BASED ASSESSMENT Rehabilitation of National Route R61 (Section 3, km 24.2 to km 75) between Cradock and Tarkastad, Eastern Cape John E. Almond PhD (Cantab.) Natura Viva cc, PO Box 12410 Mill Street, Cape Town 8010, RSA
[email protected] February 2013 1. SUMMARY The South African National Roads Agency Limited (SANRAL) is proposing to rehabilitate Section 3 of the National Route R61 (km 24.2 to km 75) between Cradock and Tarkastad, Eastern Cape. The project involves widening of the roadway and of all stormwater structures along the route. Road material is to be sourced from five new or existing borrow pits and one hard rock quarry. A Phase 1 palaeontological heritage assessment for the road project has been commissioned by Arcus GIBB (Pty) Ltd in accordance with the requirements of the National Heritage Resources Act (Act 25 of 1999). Section 3 of the R61 traverses the outcrop area of continental sedimentary rocks of the Upper Beaufort Group (Tarkastad Subgroup, Karoo Supergroup) of Early to Middle Triassic age. These are cut and baked by numerous dolerite intrusions of the Karoo Dolerite Suite of Early Jurassic age. Towards Cradock (Graaff-Reinet and Middelburg 1: 250 000 sheet areas) the sedimentary bedrocks belong to the sandstone-dominated Katberg Formation that was deposited in arid braided fluvial settings following the catastrophic end-Permian mass extinction event. Further east towards Tarkastad (Queenstown and King William’s Town 1: 250 000 sheet areas) the sedimentary bedrocks are assigned to the slightly younger Burgersdorp Formation comprising recessive-weathering reddish mudrocks and braided river channel sandstones.