Vol. 54.] GEOLOGY OF THE WITWA.TERSRAND AND OTHEE DISTRICTS. 73 



6. A Geological Survey of the Witwatersrand anc^ other Districts 

 in the Southern Transvaal. By Frederick H. Hatch, Ph.D., 

 P.Gr.S., Assoc. M.Inst. C.E., formerly of the Geological Survey of 

 England and Wales. (Bead November 17th, 1897.) 



[Plate VI — Map & SectiouSv] 



Contents. 



Page 



I. Introduction 73 



II. The Archaean Rocks 75 



III. The Cape System 7G 



1. The Hospital Hill Series 77 



2. The Wit Wat ersrand Beds 79 



3. The Black Eeef and Khpriversberg Amygdaloid 86 



4. The Dolomite Formation 86 



5. The Magaliesberg and Gatsrand Series 90 



lY. The Karoo System 91 



Notes on the Plant-Remains, by A. C. Seward, Esq., 



M.A., F.G.S 92 



V. The Volcanic Rocks 94 



VI. The Age and Greotectonic Relations of the Formations of the 



Southern Transvaal 95 



I. Introduction. 



The importance of the Witwatersrand as a gold-producing area has 

 given an impetus to geological enquiry in this part of South Africa. 

 The result has been the appearance of numerous books, pamphlets, 

 and papers.^ My apology for adding to their number by the 

 present communication is a five-years' residence in the Transvaal, 

 during which time I have had perhaps unusual opportunities 

 and facilities for closely studying the geology of the Southern 

 Transvaal, or more correctly the region lying between the Maga- 

 liesberg Range and the Vaal Eiver. Having in the course of 

 professional duties to journey backward and forward through this 

 country, I gradually became acquainted with its geological structure ; 

 and as a means of crystallizing and correlating the information thus 

 obtained, I began to lay it down on a map and have continued to do 

 so until now. The survey of some 8000 square miles of country, 

 embracing the districts of the Witwatersrand, Potchefstroom, and 

 Heidelberg, and a portion of those of Eustenburg and Pretoria, 

 being now completed, I desire to lay the results before the 

 Geological Society. 



The difficulties of geological mapping in a sparsely-inhabited 

 country, and where the inhabitants since the Jameson raid have 

 not been particularly disposed to welcome the Uitlander, may be 

 easily imagined. I do not claim for my map that accuracy in 

 detail which can only be obtained by leisurely work on a large 

 scale ; still, the main geological boundaries have been drawn with 

 as near an approximation to correctness as was possible under the 



^ Mostly German and French. 



