THE MAKING OF THE GEOLOGICAL TIME-SCALE. 2$ 



tern, and Protozoic was a provisional name proposed for pre- 

 Cambrian rocks which might be found to contain fossils.* 



In his " Silurian System," Murchison proposed Protozoic in 

 the following words: " For this purpose I venture to suggest 

 the term ' Protozoic rocks/ thereby to imply the first or 

 lowest formations in which animals or vegetables appear." f 



Without entering into the delicate question of apportion- 

 ing the honors due to each of these great English geologists,^: 

 it may be said that in this early usage of the terms, the dis- 

 tinction between Protozoic and Palaeozoic was ideal and in 

 later developments Paleozoic has been retained for that 

 lower great division of the scale containing distinct remains 

 of organisms, with the Cambrian system at the bottom. To 

 show the connection with the older nomenclature, it may be 

 noted that Paleozoic is equivalent to Primary fossiliferous, 

 and in the "Silurian System" Azoic was applied to the 

 Primitive rocks of the Lehmann system. 



Phillips's Scheme. John Phillips, in 1841, proposed to ex- 

 tend this method of classification to the whole geological series; 

 and as his scheme was apparently the first complete classifica- 

 tion constructed on this basis, it is offered as it appeared in 

 " Palaeozoic Fossils of Devon and Cornwall." 



Proposed Titles depending on the OrHina v Titl*. 



Series of Organic Affinities. lmar y 1 



{Upper = Pliocene Tertiaries. 

 Middle = Miocene Tertiaries. 

 Lower = Eocene Tertiaries. 

 {Upper '= Cretaceous system. 

 Middle = Oolitic system. 

 Lower = New Red formation. 



( Magnesianlimestoneformation. 



Palaeozoic strata : -< 



Upper? , 



( Carboniferous system. 



Middle? Eifel and South Devon. 



T , Transition strata. 



Lower = < . 



Primary strata. 



* Sedgwick, Proc. Geol. Soc., vol. n. p. 675, London, 1838. 

 f Murchison, "Silurian System," p. n. 



\ See American Journal of Science, vol. xxxix. p. 167, 1890. 

 London, 1841, p. 160. See also Penny Cyclopaedia, articles "Geology," 

 " Palaeozoic Rocks," " Saliferous System," etc. 



|| The terms are founded on the verb Ca'ca or <WG>, to live ; combined with. 

 recent ; /icSog, medial or middle ; and itttkaioS, ancient. 



