Charles Schuchert — Historical Geology, 1818-1918. 75 



The Oldest Geologic Eras. — We have seen in previous 

 pages how the Primitive rocks of Arduino and of Werner 

 had been resolved, at least in part, into the systems of 

 the Paleozoic, but there still remained many areas of 

 ancient rocks that could not be adjusted into the accepted 

 scheme. One of the most extensive of these is in Canada, 

 where the really Primitive formations, of granites, 

 gneisses, schists, and even undetermined sediments, 

 abound and are developed on a grander scale than else- 

 where, covering more than two million square miles and 

 overlain unconf ormably by the Paleozoic and later rocks. 

 The first to call attention to them was J. I. Bigsby, a 

 medical staff officer of the British Army, in 1821 (3, 

 254). It was, however, William E. Logan (1798-1875), 

 the "father of Canadian geology," who first unravelled 

 their historical sequence. At first he also called them 

 Primary, but after much work he perceived in them par- 

 allel structures and metamorphosed sediments, under- 

 lain by and associated with pink granites. For the 

 oldest masses, essentially the granites, he proposed the 

 term Laurentian system (1853, 1863) and for the altered 

 and deformed strata, the name Huronian series (1857, 

 1863). Overlying these unconf ormably was a third 

 series, the copper-bearing rocks. Since his day a great 

 host of Canadian and American geologists have labored 

 over this, the most intricate of all geology, and now we 

 have the following tentative chronology (Schuchert and 

 Barrell, 38, 1, 1914) : 



Late Proterozoic era. 



Keweenawan, Animikian and Huronian periods. 

 Early Proterozoic era. 



Sudbnrian period or older Huronian. 

 Archeozoic era. 



Grenville series, etc. 

 Cosmic history. 



The Taconic System Resurrected. 



The -Taconic system was first announced by Ebenezer 

 Emmons in 1841, and clearly defined in 1842. It started 

 the most bitter and most protracted discussion in the 

 annals of American geology. After Emmons's subse- 

 quent publications had put the Taconic system through 

 three phases, Barrande of Bohemia in 1860-1863 shed a 

 great deal of new and correct light upon it, affirming in a 



