ORIGINS OF SCIENCE IN THE ANCIENT WORLD 15 



Fig. 3. Schematic Cross-Section of the Nile Valley at Present Day. Showing 

 remains of lacustrine deposits and of two river terraces. The alluvium of 

 the modern valley floor and the present Nile appear below. Vertical 

 dimension is exaggerated. Compare with Fig. 2. Location of human 

 artifacts is indicated by figures on the right hand side as explained in 

 text. (Adapted from Breasted and Blanckenhorn.) 



2. Implements similar to (1), but found embedded at various 

 levels in the lake deposits, are believed to have been washed in from 

 the plateau, since this was the source of the material composing 

 the lake deposits. Hence some at least of the plateau implements 

 antedate the formation of the lake deposits. 



3. Many implements are found embedded within the upper 

 river terrace. These are similar to (1) and (2). The material of 

 this terrace was derived by washings from the older lake deposits 

 or from the plateau. 



4. Implements on any undisturbed surface of this terrace are 

 of later origin than (3) . 



4a. Prehistoric cliff pictures of game animals, primitive boats, 

 and the like, now found upon the upper cliffs are believed to be 

 contemporaneous with (4). 



5. Implements within the lower terrace would be regarded as 

 more recent than (4), or as washed down from the earlier forma- 

 tions above, since the material of this terrace had such an origin. 



6. Implements upon any undisturbed surface of this lower ter- 

 race would be later than (5) . 



7. Implements, fragments of pottery, etc., have been found 

 deeply embedded in the present alluvial plain. The transition 



