Explanation of Plate 20. 



Sectioyi 1 — A sketch section across the strike from Lorette to Levis in a southeasterly- 

 direction (see also Bull. Geol. Soc. Am., vol. 1, p. 464, map accompany- 

 ing Dr. Ells' paper). It includes the following terranes in their geo- 

 graphical sequence, beginning toward the northwest: a. Laurentian or 

 Archean ; h. Trenton ; c. Utica ; d. Lorraine (Hudson River of most 

 geologists) ; e. Quebec (new terrane, separate from others) ; /. Levis ; 

 and g. Sillery. The last three, e, /, and ^, form part and parcel of the 

 fossiliferous Quebec group, while 6, c, and d form the Trenton group, 

 which are separated by a fault — the great Appalachian fault (the " Que- 

 bec fault " of Ells, or the St. Lawrence and Champlain fault, or a branch 

 of it, of other geologists). 



Section 2 — Sketch section at Montmorency falls, across the measures east of the gorge 

 and across the Island of Orleans. The notation is the same as in section 

 L The Utica shales are much disturbed here, both in their contact with 

 the Trenton below and with the Lorraine shales above. Below the hori- 

 zontal Trenton, capping the Laurentian gneiss, there are found calcareous 

 sandstones of Trenton age, which have been called Potsdam " quartzites." 

 A downthrow fault passes in front of the bluff over which the waters fall. 



Section 3 — Sketch section across the measures near Montcalm market, Quebec city, 

 showing the high angle of dip and the shales with limestones inter- 

 stratified. 



Section 4 — A general view of the strata flanking the Citadel hill at the landslide of 

 1889. The structure there exhibited is that of an inclined denuded 

 anticline. 



Section 5 — Sketch section through the calcareo-bituminous rocks and compact shales 

 with conglomeratic cherty bands associated, at Cote d'Abraham, where 

 the monticuliporidae have been obtained. 



Sectioti 6 — Sketch section showing the thin, fissile and soft earthy shales of the Lor- 

 raine terrane — newer than the Utica — inclined at a considerable angle 

 along the road at Cote Sauvageau, west of Martelle tower no. 4. 



Sectioti 7 — Sketch section exhibiting the dying out of the outcrop of Lorraine or 

 newer shales on the edge or brow of the hill near Martelle tower no. 4, 

 between Cote Sauvageau (section 6) and Cote de la Negresse, where a 

 series of impure semi-crystalline, bituminous and fossilifuous limestone 

 occurs. Cote de la Negresse is west of Cote d'Abraham. The contact 

 between the two series is very much broken up, i. e., between d and e. 



Legend. 



a = Laurentian or Archean ; 



b = Trenton terrane ^ 



c = Utica terrane > Trenton group. 



rf = Lorraine terrane .^ 



e = Quebec terrane -j 



/ = Levis terrane > Quebec group. 



g = Sillery terrane ) 



(500) 



