Portuguese Territories, E. Africa. 275 



North of the Save Eiver, in the Mozambique and Zambesi 

 Companies' territories, the aspect of tlie country entirely changes ; 

 instead of sandy plains thei'e is a succession of undulations of 

 gradually increasing elevation, which beyond the Morungueze 

 reach to the summit of the plateau, at levels of 1000 to 1200 m. 

 Beyond the Lusiti River, running from south to north, is the wall- 

 like range of the Chimaniraani Mountains, the summits of which 

 are 2000 ra. above the sea. The principal rivers of this northern 

 district are the Zambesi, Pungue, Eevue, Lusiti, Busi, Mossurize, 

 and the Save. A large portion of this area consists of gneiss and 

 granite, which extend to near the coast and then disappear beneath 

 modern alluvium. The author distinguishes (1) granitoid gneiss 

 passing into granite, (2) gneiss with intercalated beds of pyroxene 

 and with garnets and amphibolites, and (3) mica schists and 

 chloritic schists. 



In the country between Lorenzo Marques and the Zambesi 

 there is a close connection between the altitude and the geological 

 structure, so that it is possible to divide it into three principal zones. 

 The lowest or coast zone, I'eaching from sea-level to 300 m., 

 consists for the most part of Tertiary sediments, modern alluvial 

 deposits, and sand-dunes. A large part of the southern districts 

 of Lorenzo Marques (except the Limbombos Mountains) and In- 

 hambane, and a small part of the Companies' territories, are included 

 in this zone. The second or middle zone, from 300 to 600 m., 

 includes the Limbombos and a large part of the northern territory, 

 and the predominant rocks are gneiss and the more recent crystalline 

 rocks, such as porphyry, porphyrites, and melaphyres. The third 

 or high zone includes the eastern slopes of the high plateau and 

 adjacent areas, with elevations between 600 and 2400 m. The 

 rocks of this zone are principally schists, with a great variety of 

 ancient crystallines, such as granites, granulites, diorites, diabases, 

 gabbros, etc. 



The gneiss areas are first seen in the latitude of the Mossurize 

 River, and from here they continue northwards without interruption, 

 forming nearly the whole of the hydrographic basin of the Busi 

 Eiver, except in one or two restricted localities where they are 

 covered by Pala30zoic sedimentary strata, which are traversed by 

 granites and other eruptive rocks. 



The more ancient sedimentary rocks of the country resemble 

 those of other adjacent parts of South Africa in the absence of 

 fossils ; and as a consequence considerable doubt exists regarding 

 their geological age. The author refers to the Silurian or Devonian 

 a thick series of argillaceous and siliceous schists and quartzites, 

 which are developed more particularly along the eastern declivity 

 of the high plateau between the Save and the Zambesi, and in the 

 Chimanimani Mountains exhibit a proximate thickness of 1000 m. 

 They have been much disturbed and compressed, and in places 

 they are traversed by diabases and granulites. No fossils have 

 as yet been found in them, and their age is conjectured from their 

 occurrence anterior to rocks considered to be Carboniferous. 



