ROYAL SOCIETY OF SOUTH AFRICA. 
VOL. V. 
THE GEEAT DYKE OF NOEITE OF SOUTHEEN EHODESIA : 
PETEOLOGY OF THE SELUKWE POETION. 
By a. E. V. Zealley, A.E.C.S., F.G.S., of the Geological Survey 
of Southern Ehodesia. 
(Communicated by permission of the Secretary, Department of the 
Administrator, Southern Ehodesia.) 
(With Plates I.-IV.) 
(Eead September 16, 1914.) 
I. — Introductory. 
The following paper is based upon work done in 1911-12 whilst 
mapping geologically the country around Selukwe. 
The large intrusion for which the name " Great Dyke of Norite " was 
suggested by the present writer in a preliminary description (Beport of 
the Director, Geological Survey, 1911, p. 13), stretches across the area 
mapped for some 30 miles from north-north-east to south- south-west. It 
continues onwards in both directions with the characters described below, 
and, as shown by F. P. Mennell Geological Structure of Southern 
Ehodesia," 1910, Q.J.G.S., vol. Ixvi., pp. 371-372), extends for some 
300 miles nearly throughout the Territory, maintaining the width of out- 
crop (about 4 miles) seen at Selukwe and elsewhere. North of the 
Zambezi similar rocks have not been described, but south of the Limpopo 
in the Transvaal precisely similar rocks belonging to the Bushveld 
Laccolite are well known, and will be referred to below. 
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