Clays derived from the Lower Dwyka Shales, occurring in the vicinity of Grahamstown
- Authors: Blignaut, J J G
- Date: 1928
- Subjects: Clay -- South Africa -- Grahamstown Clay -- Economic aspects -- South Africa -- Grahamstown Geology -- South Africa -- Grahamstown Mineralogy -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4935 , http://hdl.handle.net/10962/d1005547
- Description: The Lower Dwyka Shales in South Africa oocur south of latitude 32⁰; resting conformably upon the Witteberg quartzites, which extend as coastal mountain rangee along the length of the South Coast. The shales, being less resistant to weathering than the quartzites below, and the Dwyka Tillite immediately above, are consequently found in valleys between these two formations. In one of these valleys Grahamstown is situated; where the Lower Dwyka Shales have been eroded by the various rivulets forming the eource of the Blaauwkrantz River. A geological map of the country round Grahamstown was prepared in eome detail, showing all the various rock formations occurring in the area, the full extent of the Lower Dwyka Shales being mapped with the Dwyka Tillite and the Witteberg Quartzite along its margins. The map includes an area of about six miles by three, with the Cathedral spire occupying an approximately central position, and is prepared on a scale of 5.65 inches to one mile. Traversing was done by means of prismatic compass and pacing.
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- Date Issued: 1928