532 Arthur Holmes — Lateritic Deposits, Mozambique. 



generally down towards the streams on the eastward side, and away 

 from them on the westward side (Fig. 2). Instances could also be 

 given (e.g. south of Otetani, by the Monapo River) where the dip is 

 towards the streams from the westward side and where the laterite is 

 restricted to the westward side. In other cases no such correlation 

 is possible, laterite being equally developed on both sides, as for 

 example along the upper course of the Namieta iliver, which cuts 

 transversely across the gneiss. 



In the western part of the territory, where the mountain blocks are 

 more numerous and lofty, where the dip is more frequently at a high 

 angle, and where the streams are less liable to become completely dry 

 during the rainless season, laterite tends to occur in widespread sheets 

 as well as in individual bands. In the sheets themselves, however, 

 a broadly banded structure may often be discerned, strong, hard, 



W. -^ 



Fig. 2. — Section at the foot of the Etipoli Hills near the Ligonia Iliver, 

 illustrating the occurrence of laterite on the eastern side of a gully. 



quartzose laterite alternating with what is little more than a lateritic 

 earth capped with a hardened ferruginous cement. Such sheets are 

 common between the Chica Hange and the Ligonia Iliver, in the 

 district south of the Kibawe Mountains, and between the Mluli 

 Mountains and the Luli Kiver. In thickness the lateritic deposits 

 are very irregular, varying within a short distance from a few inches 

 to several feet. 



The relation of laterite to vegetation has been tlie subject of very 

 diverse opinions. In Mozambique it was evident that where the 

 forest and undergrowth were thick no laterite occurred at the surface. 

 In fact, the deposit was almost always associated with areas where 

 the superficial debris was clean and free from organic matter and the 

 so-called ' humus ' acids. It has been asserted that the humus acids 

 can decompose silicates, but since the humus acids are themselves 



