Photo: Mapping Consultants Ltd. 
Fig. 4. Savannas at Guinea Border. Two concentric walls indicate the successive 
growth of the original town. The scale of the sketch is 1: 10,000. 
One of the three discovered walls has been examined on the ground. 
For that reason a passage had to be cut through the high and very 
thick grass by cutlasses. In accordance with the photogrammetric inter 
pretation an earth wall was found, about one metre in height and 
three metres at the base, a moat outside the wall included, fig. 5. 
An explanation will certainly be of interest why such an anomalous 
ness of the terrain can be distinguished from the surrounding ground. 
One reason is that the grass upon the crest of the earth fence has 
another colour than the adjacent vegetation resulting in a contrast on 
the negative. Another reason may be a thin shadow line along the wall. 
An essential reason is also the systematical shape of the feature in 
question. 
I have reported these things to Dr. G. W. Harley before he left the 
(ianta Mission. He listened to my report with great interest and then 
told me that the occurence of such old defence walls were familiar to 
him from his travels in West Africa. In his opinion these defence 
walls belonged to an epoch about two hundred years ago. 
Some examples of such old towns or villages, revealed by the sur 
rounding defence walls, situated in Liberia, will here be presented 
giving evidence of the human struggle for life at that time. 
5? 5