00999cam a22002651 4500 gs 23000005 DLC 20260227111327.0 860307s1922 sa abf b f000 0 eng c gs 23000005 (OCoLC)13253653 Library, U.S. Geological Survey NhD DLC premarc QE324 .A3 no. 20 Wagner, Percy Albert. The Pretoria salt-pan, a soda caldera, by Percy A. Wagner ... Pretoria, The Government Printing and Stationery Office, 1922. 136 p. XIX pl. (part fold.; incl. fold. col. map) tables. 25 cm. South Africa. Geological Survey. Memoir no. 20 At head of title: Union of South Africa. Department of mines and industries. Bibliographical foot-notes. Geology, Economic South Africa. Mines and mineral resources South Africa. Salt mines and mining South Africa. 26203 26203