Outlines of the Geology of Mozambique. 413 



will prove of interest to students of East African geology, especially 

 in their bearing on problems of theoretical interest concerning the 

 geological history of that portion of the globe. 



With the exception of a narrow coastal strip consisting of Cretaceous 

 and Tertiary sediments with some volcanic rocks, the whole country 

 consists of a complex of gneisses and other foliated rocks intruded 

 upon by massive igneous rocks and their attendant dykes. Although 

 we proceeded as far inland as latitude 37° E., no further signs of any 

 sedimentary rocks were met with, liocks probably of Karroo age 

 occur immediately to the north in the Lujenda Valley, to the east in 

 Ih'itish Central Africa, and to the south in Zambesia, but in each case 

 they owe their preservation to trough-faulting. Denudation appears 

 to have entirely removed such formations from the surface of 

 Mozambique. The oldest sediments lying on the metamorphic rocks 

 are of Lower Cretaceous age, and consequently there is little direct 

 geological evidence for the age of the complex. However, judging 

 from their lithological features, the intricacy of their structure, and 

 their similarity to corresponding fundamental rocks in other parts of 

 the globe, we feel justified in assigning these rocks to the Archaean. 

 Particularly striking is their resemblance to the rocks of British 

 Central Africa, British and German East Africa, and Madagascar; 

 for this consists in not only their detailed field characteristics and the 

 peculiar ' inselberge ' landscape they give rise to, but also in their 

 mineral and chemical characters. 



The country inland from Mozambique gradually changes in type. 

 After the low-lying sedimentary zone is crossed the surface is that of 

 a gently rising plateau from which many isolated peaks and hills 

 arise. They produce a peculiar type of topography which also 

 occurs in German East Africa, where it has been examined and its 

 origin discussed by Bernhardt.^ In Northern Nigeria^ the scenery 

 is very similar, and this type appears to be a marked characteristic of 

 the gneiss and granite regions of Africa. Fantastic peaks, rocky domes, 

 and cone-shaped hills rise precipitously from the plateau, like islands 

 surrounded by a verdant sea of forest. By their aggregation lofty 

 mountain blocks and ranges are formed, and one of the most extensive 

 of these in Mozambique is the Chica range, which stretches for 20 miles 

 in a N.N.E. and S.S.W. direction, about 150 miles from the coast. 

 Further west are the great massifs of Bibaue and Inago, rising to 

 5,000 and 6,000 feet respectively, whilst in the western limit of the 

 country rise the famous JSTamuli Peaks, so long conjectured to be of 

 volcanic origin, but consisting of a huge block of granite and gneiss 

 Avith conical peaks, and rising to 8,000 feet above sea-level. These 

 four mountain groups define the watershed of the territory, and from 

 them the rivers flow north, south, and east. 



In the metamorphic series of Mozambique there are but few 

 representatives of true schists. From the north-east of the territory, 



^ W. Bornhardt, Die Oberfldchengestalttmg und Geologie Deutsch-Ost-AfriJca, 

 Bd. vii, Berlin, 1900 ; see especially pp. 34-9. 



- J. D. Falconer, Geology and Geography of Northern Nigeria, London, 

 1911 ; see especially plates v, vii, and xvii. 



