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THE VOLCANOES OF GEIQUALAND EAST. 

 By E. H. L. Schwaez, A.E.C.S., F.G.S. 



Published ivith the iwrmission of the Geological Commission. 



(Eead July 30, 1902.) 



The Drakensberg Mountains have for a very long while been 

 known to be of volcanic origin ; the amygdaloid with which they are 

 capped is easily recognised to be an undoubted volcanic lava which 

 has been poured out on the surface of the earth, as opposed to a 

 trap rock, in this country principally dolerite, which has been 

 injected into the strata without any vent whereby it could come to 

 the surface. Four years ago Mr. Churchill contributed a paper to 

 this Society on the amygdaloids of the Drakensberg Mountains in 

 Natal, and many other writers have also called attention to the 

 character of the rocks which form this range. 



In 1878 Mr. E. J. Dunn made a detailed survey of the country 

 round Molteno and Jamestown, which lie at the western end of the 

 Drakensberg range, and in the map accompanying the report he 

 shows three centres of eruption, two near Molteno and one near 

 Jamestown. In an unpublished map by him of the country east of 

 Jamestown he shows two more centres of eruption. Although he 

 described these volcanic pipes with accuracy, and saw the bearing 

 the discovery of them had on the elucidation of the geology of this 

 region, the fact seems to have been generally overlooked, and no 

 further volcanoes had been discovered till the geological survey 

 party recently found some nineteen or twenty well-marked vents in 

 Matatiele. Mr. Dunn lays stress in his report on the similarity of 

 these vents wdth the diamondiferous pipes of Kimberley and the 

 w^est of the colony, but in spite of the similarity of the structure, 

 both being large vertical pipes piercing the strata and filled in with 

 ejected material which has fallen back and clogged up the hole, yet 



