G. Schuchert — Pre-Cambrian Nomenclature. 481 



age is the age in the earth's history preceding the appearance 

 of animal life," which he then held ceased with the Potsdam 

 or the Cambrian. Earlier H. D. Kogers* had used both 

 Azoic and Hypozoic in a modified sense, thus : 



" Azoic (Gr. a, without, 2oe, life). — Applied to a group of 

 rocks underlying the Palaeozoic, and destitute of all traces of 

 once vital organisms." 



" Hypozoic (Gr. hypo, under, and zoe, life). — A term for the 

 gneissic and other rocks which lie beneath the fossil if erous 

 strata. The term is conveniently restricted to the more ancient 

 metamorphic rocks which underlie the Azoic or semi-meta- 

 morphic strata, which are also destitute of fossils, but which 

 in many countries immediately support the Palaeozoic, or those 

 containing organic remains." On page 742 it is used in the 

 sense of the oldest rocks, beneath the Azoic. 



Sir William Loganf refers the Huronian series and the Lau- 

 rentian series to the Azoic and remarks as follows : "To the 

 Azoic rocks no local names have yet been applied in any part 

 of America except in Canada, and as these rocks are here 

 more extensively exposed than anywhere else on the continent, 

 . . . the names of the Laurentian and the Huronian systems 

 or series . . . are allowed to remain unchanged." 



According to the history above recited we should retain the 

 term Hypozoic if there is but one geologic era back of the 

 Cambrian, and the significance of the word is in harmony 

 with the other accepted era terms in that it implies that there 

 is life — of course as yet almost wholly unknown — in the rocks 

 below the Paleozoic. In this event Azoic becomes a synonym, 

 and further, the word is a misnomer in that it labels the pre- 

 Catnbrian rocks as being without life. However, as we now 

 know that there are at least two eras back of the Cambrian, 

 the question arises, can we redefine Hypozoic and Azoic so as 

 to be expressive of modern views? To all holding that life 

 existed during Ontarian and Huronian time as defined by 

 Lawson, it is at once apparent that Azoic should be rejected, 

 and as Hypozoic was based upon a theoretic conception and 

 not upon a defined rock area, it also seems to have no present 

 value. As the writer holds that Eozoon canadense is evidence 

 of algal life, and as Walcott has demonstrated the presence of 

 much life in the younger pre-Cambrian strata, it seems best to 

 reject the names Azoic and Hypozoic. This becomes all the 

 more advisable if there are three eras back of the Cambrian. 



The term Archeozoic was proposed bv Chamberlin and 

 Salisbury in 19064 



The evidence now being unearthed b}' geologists in the 



*Oeology of Pennsylvania, ii, Pfc. II, 1859, 1025, 1026. 

 t Geology of Canada. 1863, 20-21. 

 X Geology, ii, 1906, 137-139. 



