292 miss c. a. raisin on [May 1903, 



21. Petrological Notes on Rooks from Southern Abyssinia, 

 collected by Dr. Reginald Xgettlitz. By Catherine A. 

 Raisin, D.Sc Lond. (Communicated by Prof. T. G. Bonnet, 

 D.Sc., LL.D., P.R.S., F.G.S. Read March 11th, 1903.) 



[Plate XXI— Map.] 



Contents. p ao . e 



I. Introduction , 292 



II. Crystalline Bocks , 293 



III. Volcanic Rocks 295 



IV. Sedimentary Rocks 302 



V. Specimens brought back by Lord Lovat 304 



Thermal Spring : Analysis of Water 305 



I. Introduction. 



An interesting account of a journey into Southern Abyssinia was 

 given in the Journal of the Royal Geographical Society for 19.00, 

 by Mr. H. Weld Blundell. 1 He followed a route roughly westward 

 from Berbera through Somaliland and Southern Abyssinia, then 

 turned northward to the Blue Nile and into the Sudan. On this 

 expedition Dr. R. Kcettlitz collected a large number of rock-specimens 

 which (at the kind suggestion of Mr. Teall), together with some 

 obtained by Lord Lovat, were entrusted to me for description.* 

 The absence of the former on the Antarctic Expedition makes it 

 impossible to submit these notes to him for revision. But the 

 following brief statement is condensed from a topographical sketch 

 which he posted to me from the ship Discovery at Lyttelton 

 (New Zealand) in the spring of 1902, and a more general account 

 by him will be found printed as an appendix to Mr. Blundell's 

 paper mentioned above. A map of the route was published with 

 that paper, from which I have copied the spelling for the place- 

 names, where possible. I have identified a few other localities on 

 the British War Office map of the district, but the remainder had 

 to be taken from the rough pencil-labels. 



The expedition crossed the coastal plain from Berbera, passing 

 knoll-like isolated hills, the road gradually rising to the edge of the 

 plateau, where the shattered rocky ground often exposed schistose 

 and granitic masses. Overlying these, sedimentary beds and 

 volcanic rocks were seen in places, and occasionally flat-topped 

 basaltic hills occur. In the great volcanic district of Southern 

 Abyssinia, sheets of basalt are often exposed, sometimes vesicular 

 and scoriaceous, especially at the surface of the flows, sometimes 

 exhibiting columnar structure. On the Hawash Plain, many hills 

 are more or less complete volcanic cones, with the craters preserved. 



1 Geogr. Journ. vol. xv (1900) p. 97. 



2 Unavoidable delays occurred in the transmission of some of the collections, 

 so that these notes appear somewhat late. 



