286 C. SCHUCHERT MEDINA AND CATARACT FORMATIONS 



fauna first developed by Conrad and later supplemented by Hall. We 

 can no longer use the term Medina in the old sense to include the Eich- 

 mondian and Medina se7isu stricto, since by general consent through a 

 half century of geologic endeavor the line distinguishing the Ordovicic 

 from the Siluric has been drawn in America and Europe at the top of 

 the Eichmondian and its equivalents, and beneath the fossiliferous Medina 

 (or at least so by inference) or lower formations having the faunal im- 

 press of Siluric time. The two series of deposits are marked by dis- 

 similar faunas and are separated by a time break, to which hiatus no fur- 

 mations are as yet referable as having faunas that will bridge the life of 

 the Eichmondian (Ordovicic or Cincinnatic) and the Medina. For these 

 contacts see plate 13, figures 1 and 2, and plate 14, figure 2. Even if 

 such transition faunas were at hand, it would then not necessarily follow 

 that the Eichmondian is better placed in the Siluric system. It remains 

 for those departing from the old and accepted classification to show the 

 desirability for this striking change. ' 



Grabau is also correct in restricting the term Medina to the upper or 

 sandy Medina of Hall, and there was therefore no need for Clarke to 

 propose Albion to take its place, as he has recently done; the term is, 

 however, adopted in the lately published Niagara folio.^^ Even if it were 

 necessary to use another name than Medina, Oneida of Yanuxem could 

 well have been made to serve this purpose. On the other hand, the 

 writer well understands why Albion was proposed, this being due to the 

 view that Queenston and Eichmondian are better referred to the Siluric 

 than to the Ordovicic. This opinion is, however, at variance with all 

 previous classifications and the writer lias lieretofore protested against it. 

 He is prepared to show that the opinions of the older stratigraphers in 

 America and Europe are correct in their general premises, and, further, 

 that on the principle of diastrophic movement and faunal dissimilarity 

 the Siluric invasion did not begin with the Eichmondian, but rather, as 

 so long held and without dissenting opinion, at the base of the fossilifer- 

 ous Medina or other older formations that are clearly younger than Eich- 

 mondian — for example, Lyckholm and Borkholm of Estland, Etage 5 of 

 Norway, Trinucleus beds of Sweden, or Keisley of Britain. 



If we are to be purists in nomenclature and strict adherents to the rule 

 of priority, then Conrad's term Niagara sandstone of 1836 (see Part II 

 for detail) clearly has right of way over Medina sensu strwto. Hall 

 should have adopted this term, as he gives evidence that he knew of its 

 existence ; but, as is well known, he was a o^eat and forceful leader, never 



IS Kindle and Taylor: Geol. Folio No. 190. U. S. Geological Survey, 1913, p. 6. 

 Why Kindle did this is explained in Science, vol. 39, 1914, p. 915. 



