00485nas a2200073   4500008003900000245026000039210006900299856004300368       1986                          d00aFRICK, C. and MALHERBE, S.J. 1986. The geology of the Roodeplaat caldera, north-east of Pretoria. Bulletin, Geological Survey of South Africa, 79: 1-44.LOMBAARD, B. 1930. The geology of a centrocline, 18 miles north-east of Pretoria. Transactions and Proc0 aFRICK C and MALHERBE SJ 1986 The geology of the Roodeplaat calde  uhttps://alkcarb.myrocks.info/node/7439