1*76 Canadian Record of Science. 



area of considerable extent occurring to the south in the 

 Laurentian of the State of New York. l 



The stratigraphical relation of the anorthosites to the 

 Grenville and Ottawa series are as yet somewhat doubtful. 

 In most cases these are difficult to determine because the 

 localities where these rocks are found are generally diffi- 

 cult of access and the surface is often heavily drifted or 

 covered by a dense forest growth. 



Sir William Logan 2 whose views were chiefly based on 

 an investigation of parts of the Morin area thought that 

 they probably belonged to a newer sedimentary formation 

 which lay unconformably upon the Grenvilie series, and 

 which although consisting principally of anorthosite, yet 

 included interstratified beds of orthoclase gneiss, quartzite 

 and limestone. 



This opinion was apparently supported by the observa- 

 tions which Eichardson made on these rocks along the 

 lower St. Lawrence, and in the atlas which accompanied 

 the report of the Geological Survey of 1863, Logau assign- 

 ed these anorthosites together with the accompanying 

 gneisses to a distinct and higher series which he called the 

 Upper Laurentian. 



S terry Hunt believed that these rocks were identical 

 with the norites of Esmark and called them in consequence 

 of this the Norian Series. 3 



No detailed study of the stratigraphical relations of 

 these rocks has hitherto been made in the case of any of 

 the areas, but writers other than the above have made 

 definite statements without exact knowledge to the effect 

 that they form a series of strata which rest unconformably 

 upon the Grenville series. 



The sequence of these rocks is, according to Logan, as 

 follows : 



Norian series = Upper Laurentian. 

 Grenville series=Upper division | L Laurentian. 



Ottawa series = Lower division j 



1 Emmons, Rep. of the geology in the second district of New York, 1842. 



2 Logan, Rep, Geol. Survey of Canada 1863, p. 839. 



3 Sterry Hunt, Chemical and Geological essays, p. 279. Also Special Rep. on 

 the Trap Dykes and Azoic Rocks of S. E. Pennsylvania. 2nd Geol. Survey of 

 Pennsylvania 1878, p. 160. 



