70 
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
Stereopair - Metasediments, Tegina Sheet. Nigeria 
Subdued soil covered ridges (points 1 and 2) are typical of those which in metasedimentary 
areas usually indicate the trace of the bedding. The distribution of vegetation, emphasizes 
the direction of the ridges. 
The field determination of the strike of the metasediments could be difficult in this area, 
whereas the ridges can be followed easily on the aerial photographs. 
Stereopair - Synform in metasediments, Mahenge Sheet, Tanganyika 
Crystalline dolomitic limestones interbedded with undifferentiated gneisses. The limestones 
(points 5 and 7) erode more quickly and form valley bottoms. Ridges 1, 2, 3, 4, 6 and 8 re 
present gneisses. Limestone-gneiss contact can be traced and the strike of the bedding, re 
presented by this contact, can thus be obtained from the photographs. 
Within the gneisses, the photographs provide structural details which could probably be 
used in their differentiation. Field observation showed that the gneissic foliation was parallel 
to the ridges 1, 2, 3 and 4 and thus parallel to the limestone-gneiss bedding contact. It is 
probable that these ridges 1, 2, 3 and 4 indicate the direction of relic bedding within the 
gneisses. (Field data: Mr. E. A. Stephens, Overseas Geol. Surv.) 
Fig. 2