4 



" There seems to be a fairly general agreement that in the past 

 there have been climatic oscillations in the northern half of Africa. 

 It is further agreed that in former times conditions more arid than 

 those of to-day prevailed over much of the Sudan. The division of 

 opinion concerns the present chmatic trend. Local observers maintain 

 that the present tendency is for the Sahara to encroach on the Sudan. 

 MM. Gautier, Chudeau and Dr. Falconer, on purely geological grounds, 

 maintain that the contrary is the case. May it not be that the 

 geologists, owing to the breadth of view with which they regard both 

 space and time, have overlooked a minor oscillation, namely, the present 

 widespread tendency towards increasing aridity ? 



" M. Hubert (also a geologist) is in agreement with MM. Gautier 

 and Chudeau regarding climatic oscillations in the past, but he denies 

 their contention that the present tendency is towards increasing 

 humidity. In this, however, he is in entire agreement with the 

 experience of the natives and the opinion of local observers, whose con- 

 clusions are based on evidence which, although of very great value, 

 appears not to have been properly appreciated by MM. Gautier and 

 Chudeau. His valuable conclusions, which apply equally to the 

 Northern Provinces of Nigeria and perhaps to many other parts of the 

 Sudan, may be briefly summarised as follows : — 



(i) At a remote epoch there was a period when the Senegal 



region was well watered, but to-day this region has become so 



arid that the livelihood of the natives has become precarious. 



(2) The change from more humid" conditions to the aridity of 

 to-day has been marked by climatic fluctuations of dry and wet 

 periods always with a total effect of ever-increasing aridity. 



(3) During a very short period so rapidly has desiccation pro- 

 gressed that its effects have been noted by actual observers on the 

 spot. 



ip -p ^ ^ H^ 



"The destructive hand of man is as active an agent of desiccation in 

 the Nigerian Sudan as in the Sahara. The establishment of forest 

 reserves has done something to hmit his depredations, but the only 

 real remedy for deforestation lies in the introduction of some system of 

 permanent cultivation. To this end much may be done by the develop- 

 ment of irrigation and rotation of crops, but at best so great a change 

 in the native methods of agriculture must take a very long time to 

 achieve." 



These remarks, made with reference to Northern Nigeria, are equally 

 applicable to the Sudanese Zone of the Gold Coast. Mr. Bovill con- 

 siders the displacement of the Sudanese Zone : here in the Gold Coast 

 we are confronted with an earlier stage, namely, the displacement of 

 the Guinea Zone by the Sudanese. 



