334 



CONDITIONS OF DEPOSITION 



by quiet water that allowed the fine-grained sandy 

 mud to accumulate. The whole thickness of rock at 

 present exposed is but some thirty feet, and it exhibits 



FIG. 28. Ammonite, Mortoniceras soutoni (Baily) (reduced) after 

 Woods, from the Umzamba beds. 



this alternation of fine and coarse sediments throughout. 

 The same species of mollusca appear to be distributed 



