RfiSUMfi OF LITERATURE. 99 



Laavson, Andrew C. Lake Superior stratigraphj' : Am. Geologist, Vol. VII, 

 1891, pp. 320-337. 



Lawson discusses Lake Superior stratigraphy in an article which 

 owes its inception to the paper by Prof. C. R. Van Hise entitled "An 

 attempt to harmonize some apparently conflicting views of Lake Superior 

 stratigraphy,"" which is abstracted above, p. 97. 



Lawson argues for the indivisibility of the Archean, meaning by this 

 term all those rocks that existed prior to the denudation epoch, during 

 which time the floor was formed on which has since been deposited 

 with strong unconformity the Animikie series and its equivalents. The 

 Archean thus includes, in upward succession, the Laurentian gneiss and 

 granite, the crystalline schists of the Coutchiching, and the crystalline 

 schist and elastics of the Keewatin. The Coutchiching and Keewatin are 

 so knit together by' the Lauj-entian foliated granite as to warrant the union 

 of all of these under the term Archean. 



Lawson then argues against Van Hise's correlation of tlie Upper Ver- 

 milion with the Animikie series. He states that the granite of Saganaga 

 Lake is found, with abundant and clearl}?- observed evidences of eruption, 

 breaking through the Keewatin rocks, including the Upper Vermilion (Van 

 Hise) fragmental rocks of Ogishki Lake with their associated slates and 

 grits. It is concluded that the break between the Upper and the Lower 

 Vermilion described by Van Hise is within the Keewatin group, dividing 

 it into an upper and a lower series, and that this break is therefore below 

 the Animikie; that these series are united by the Saganaga granite intru- 

 sions and that they belong in the schist-granite-gneiss complex of the 

 Archean; hence this break is below the Animikie. It is further said that 

 the conglomerates of the Upper Kaministiquia series come out close to the 

 shores of Thunder Bay and form the basement upon which the undisturbed 

 Animikie rock rests with strongly marked unconformity. The following 

 succession for the region northwest of Lake Superior is presented: 



IKeweenawan, or Nipigon group. 

 Unconformity. 

 Animikie group (possibly Huronian). 



«Am. Jour. Sci., 3d series, Vol. XLI, 1891, pp. 117-137. 



