7 is the original, 8 the plaster counterpart showing the true sur- 

 face. For the purpose of reversing the relief, figure 8 is placed so 

 that the depressions expand upward or toward the top of the plate. 

 This is *' mud flow " — 7, as it is found in natural cast ; 8, as it was 

 made by rills flowing down the beach ( from bottom to top of plate). 



[212] 



