Handbook of Paleontology 203 



graphite found so widely spread in these ancient rocks. 

 This graphite is largely derived by the metamorphism of 

 carbon from organic bodies. It has been shown that the 

 atmosphere and particularly the hydrosphere of the 

 Archeozoic must have been of a nature capable of sup- 

 porting' life. In our oceans today numerous small crus- 

 taceans, countless jellyfishes and an abundance of micro- 

 scopic life are found living near the surface where there 

 is an abundance of food supply, and the chances for their 

 preservation as fossils would be very small since hard 

 parts are usually necessary for preservation. A primor- 

 dial life might well be expected in the Archeozoic of the 

 nature of the larval forms of today, soft-bodied creatures 

 too perishable and minute to be preserved as fossils. The 

 highly organized fossils of the Cambrian show a degree 

 of specialization that indicates a long period of preceding 

 life. 



The Proterozoic rocks which were so long deemed non- 

 fossiliferous have yielded a variety of forms in the past 

 twenty-five or thirty years. Silicious sponge spicules, 

 possibly Foraminifera, worm tubes and trails, bacteria 

 and algae. The indications are that there was an abun- 

 dance of marine algae of a calcareous nature in the seas of 

 this time and thousands of feet of Proterozoic 

 limestone were built up by them. Blue-green algae are 

 also responsible for certain limestone beds. Just as in 

 the Archeozoic, there must have been countless numbers 

 of soft-bodied primitive forms not suited to preserva- 

 tion as fossils. The development of hard coverings 

 came later probably as a protection and due largely to 

 competition. 



Climate. The presence of a glacial boulder con- 

 glomerate (tillite) in the Huronian series of Canada 



