284 mr. a. j. c. molynecx on the [May 1903, 



the Forest Sandstones — the same volcanic action being the first cause 

 of the red colour of the beds of this portion of the country. 



After the deposition of the Forest Sandstones, the region was 

 subjected to a gradual and irregular upheaval, extending over the 

 whole area. Nearest to the now reduced plateau the beds were but 

 little removed from their horizontal position, but near the Sijarira 

 Range there was greater displacement, and faults and dislocations 

 of strata were frequent along what is probably a line of great 

 weakness. 



On the region becoming dry land, it is probable that desert- 

 conditions prevailed in parts, for many of the sands in the neigh- 

 bourhood of Shiloh are rounded in a manner that suggests aeolian 

 agency, and volcanic action again reached the surface in the basalt- 

 sheets of that locality. 



Since that period, in the area of the northern sediments, the 

 country has been subject to continuous denudation, removing the 

 higher sedimentary beds, and again exposing the basement-schists 

 and granites to decay. 



On the west the area of the Kalahari Desert was only partly 

 raised, and it remained an inland sea into Tertiary times. But 

 the deposits from the more elevated areas around gradually closed 

 in, and are even now rilling up the country ; for the Kalahari, in 

 the few years in which it has been known, has given evidence of the 

 drying-up of the rivers flowing towards it, and the great lakes are 

 becoming brackish, or exist only as salt-pans. 



During later times the Tuli district was subject to a period of 

 great volcanic activity, and this so recently that the cones remain 

 as prominent hills, having characteristic curved slopes, especially 

 noticeable around Fort Tuli. 



These volcanic deposits are the last addition to the building-up 

 of this portion of South Africa, which has since been at the mercy 

 of processes of gradual erosion and decay, for even its debris find 

 no resting-place in the country, but are carried away by river- 

 systems to form the deltas at the mouths of the Zambesi and the 

 East-Coast rivers. 



VIII. Bibliographical List. [By Walcot Gibson, Esq., F.G.S.] 



Guyot, P. — ' Sur la Houille du Muaraze en Zambesie.' Compt. Rend. Acad. Sci. 

 Paris, vol. xcv (1882) p. 355. 



Lapierre, E. — 'Sur le Bassin houiller de Tete (Region du Zambeze) ' : & Zelller, 

 R. ' Note sur la Flore du Bassin houiller de Tete (Region du Zambeze).' 

 Ann. des Mines, ser. 8, Mem. vol. iy (1883) pp. 585-98. 



Kuss, H. — ' Note sur la Constitution geologique d'une Partie de la Zambesie.' Bull. 

 Soc. Geol. France, ser. 3, vol. xii (1884) pp. 303-17 & Bull. Soc. Geogr. 

 2 hme trimestre (1882). 



Rugg, R. — ' Matabeleland, its Goldfields, Boundaries, Geology, Minerals & other 

 Resources, compiled from official Information and the Travels of Living- 

 stone, Mauch, Baines, Selous.' London, 1890. 



Stuart, J. M. — ' The Ancient Goldfields of Africa, from the Gold Coast to Mashona- 

 land.' 4to, London, 1891. 



Sawyer, A. R— 'The Goldfields of Mashonaland.' 8vo, London, 1894. 



Chalmers, J. A., & Hatch, F. H. — ' Notes on the Geology of Mashonaland & 

 Matabeleland.' Geol. Mag. 1895, pp. 193-203. 



