( 495 ) 



XIII. — Contributions to the Geology of Benguella. By Professor J. W. Gregory, 



F.R.S., D.Sc. (With Two Plates.) 



(MS. received June 2, 1915. Read June 28, 1915. Issued separately August 14, 1916.) 



I. Introduction and Previous Literature 

 II. Geological Observations — 



A. The Coast Zone and the Cretaceous 



(1) The Catumbella Section 



(2) South-east of Lohito 



(3) From Lobito to Hanha . 



B. Benguella to the Upper Catumbella River 



C. Oendolongo Mountains . 



D. From Lepi to Huambo . 



E. Huambo to Ochilesa 



F. Ochilesa to Saccanjimba . 



CONTENTS. 







PAGE 









FAQE 



. 495 





G. The Bulu-Vulu to Huambo . 

 (1) The Bulu-Vulu . 





518 



518 



. 498 





(2) Cambenge and the Umbal 





518 



. 499 





(3) The Umbal to Huambo . 





519 



. 501 



III. 



The Correlation of the Benguella Series — 







. 502 





A. The Mesozoic Rocks 





521 



er 504 





B. The Older Sedimentary Rocks on 



the 





. 507 









522 



. 509 





C. The Eozoic Gneisses 





528 



. 511 





D. The Volcanic Rocks and Intrusive Rocks 





. 515 





of Undetermined Age . 





528 





IV. 



The Tectonic Geology .... 





529 





V. 







532 



I. Introduction and Previous Literature. # 



Benguella is a province of Angola, the chief Portuguese colony in western Africa. 

 From the chief town, Benguella (lat. 12'35° S.) and from Catumbella (lat. 12'25° S.) 

 old-established trade routes go inland on to the Benguella plateau, and across it 

 along the watershed between the Congo and the Zambesi to Katanga and the Upper 

 Congo. The geographical pioneers in this part of Africa showed that the land rises 

 in steps from the coast to a high plateau, which consists of a foundation of ancient 

 crystalline and sedimentary rocks, and is flanked by younger marine beds along 

 the coast. 



Angola is divided into three provinces, of which the northern, Loanda, and the 

 southern, Mossamedes, are better known geologically than the middle province, 

 Benguella. The geology of Loanda is the most varied, and the first important con- 

 tribution to the interpretation of its structure was by Livingstone, who crossed it 

 during his trans-African march from the Upper Zambesi to the coast at Loanda. Of 

 Benguella he saw only the far interior, and he reached the western edge of the 

 African plateau in Loanda. Welwitsch (1889), the well-known British Museum 

 botanical collector, made important geological observations in the same region and 



* The bearings given are from true north. The variation has been taken as 18° W. ; at Benguella it is 

 18° 10' W. ; at Huambo Fort 17° 53' ; it decreases to the north-east. 



The spelling of place-names varies considerably, and K has been often used instead of C. I have followed in 

 most cases the spellings adopted on the Portuguese map of Angola (2nd edit., 1910) and by the Benguella Rail- 

 way Co. 



References are given by the author's name and date to the list at the end, 



TRANS. ROY. SOC. EDIN, VOL. LI, PART III (NO. 13). 72 



