174 . ME. G. W. LAMPLTJGH ON THE [May I907, 



up to the margin of the Eatoka Basalts. My foremost object was 

 to determine the character of the junction between the basalt and 

 the sandstone-series ; but in doing this I obtained some knowledge 

 of the structure of this coalfield. 



The engineer's report above cited contains a rough diagrammatic 

 section across the field, and some details respecting the succession 

 of the coal-measures. The Wankie coalfield is referred to, but not 

 described, by Mr. Molyneux in his paper on 'The Sedimentary 

 Deposits of Southern Rhodesia ' 1 ; and he classes these deposits, 

 along with those of other Ehodesian coalfields, under the term 

 Matobola Beds. Mr. Molyneux seems, however, to have had in 

 mind the probability that the next higher division of his scheme 

 of classification — the ' Escarpment Grits ' — was likewise represented 

 in the district 2 ; and I think that this is indeed the case. 



Athough no fossils had been found in this field, Mr. Molyneux 

 obtained some palseontological evidence from other areas in favour 

 of the 4 Permo-Carboniferous ? age of the Matobola Beds, which thus 

 fall into line with the coal-bearing deposits of the Transvaal and 

 Natal. Some ill-preserved plant-remains which I collected near 

 Wankie lend support to this conclusion. 



The series developed around Wankie consists mainly of massive 

 irregularly-bedded sandstones, generally coarse in grain and some- 

 times rough and pebbly, with subordinate beds of micaceous sandy 

 shale, clay -shale with ironstone-nodules, carbonaceous shale, and coal. 

 The fine-textured deposits are subject to rapid changes laterally, 

 but on the whole tend to occur as a middle division between the 

 massive and more persistent sandstones. 3 These softer middle beds 

 are well exposed in the hollow in which the coal-mine is situated, 

 while the rugged kopjes to the north and south of it reveal under- 

 lying and overlying sandstones. The beds frequently swing into 

 broad dome-shaped undulations, but dip as a whole northward. 



The succession across the hollow about a mile south-east of the 

 mine is shown in Section 2 (PI. XYII) ; and 4g miles farther west, 

 near the old Palls road, the sequence is as in Section 3 (PI. XVII). 

 On traversing the interveniug ground, my impression was that these 

 two sections were complementary, the base of the second (No. 3) 

 being stratigraphically a little above the top of the first (No. 2) ; 

 but my examination was not sufficiently close to eliminate the 

 possibility of duplication by cross-faulting, which is suggested by 

 the points of resemblance in the sections. 



The curious ferruginous crust on the upper surface of some of the 

 massive grits where these are overlain by shale, and the local 

 induration of the top of the grit beneath this crust into quartzite, is 

 noteworthy, as alteration of similar type appears to be still in 



1 Quart. Journ. Geol. Soc. vol. lix (1903) p. 281. 



2 Ibid, table on p. 278. 



3 In the general section given in the report published in the ' Colliery 

 Guardian' vol. lxxxiii (1902) p. 392, three main sandstones are recognized, and 

 are respectively named ' Upper, Middle, and Lower Grits.' 



