Chap. XX. GEOLOGY. 2C9 



through which we were to pass to render me e\ery assistance 

 in their power. 



We left Loanda on the 20th September, 1854, and passed 

 round by sea to the month of the river Bengo. Ascending 

 this river, we went through the district in which stand the 

 ruins of the convent of St. Antonio ; thence into Icollo i Bengo, 

 so named from having been the residence of a former native 

 king. We here visited a large sugar manufactory worked by 

 a vast number of slaves ; but somehow or other, although the 

 flat alluvial lands on the banks of the Senza or Bengo are well 

 adapted for raising sugar-cane, the establishment was far from 

 being in a flourishing condition. The water of the river is 

 muddy, and it is observed that such rivers have many more 

 mosquitoes than those which have clear water. We were told 

 that these insects are much more numerous at the period 

 of new moon than at other times ; however this may be, 

 we were thankful to get away from the Senza and its insect 

 plagues. 



The whole of this part of the country is composed of marly 

 tufa, containing the same kind of shells as those at present 

 found in the sea. As we advanced eastward and ascended 

 the higher lands, we found eruptive trap, which had tilted up 

 immense masses of mica and sandstone schists. The mica 

 schist almost always dipped towards the interior of the 

 country, forming the mountain-ranges of Golungo Alto. The 

 trap has frequently run through the gorges made in the 

 upheaved rocks, and at the points of junction between the 

 igneous and older rocks there are large quantities of strongly 

 magnetic iron-ore. The clayey soil formed by the disintegra- 

 tion of the mica schist and trap is admirably adapted for the 

 coffee, and it is on these mountain sides, and on others pos- 

 sessing a similar red clay soil, that this plant has propagated 

 itself so widely. The meadow-lands adjacent to the Senza 

 and Coanza being underlaid by the same marly tufa which 

 abounds towards the coast, and containing the same shells, 

 shows that previous to the elevation of this side of the country 

 it possessed some deeply indented bays. 



2Sth September, Kalungwembo. — We were still on the same 

 path by which we had come, and, having escaped from the 

 mosquitoes, we could enjoy the scenery. Ranges of hiT.fl 



