144 ROYAL SOCIETY OF CANADA 
the presence of shore sand or detrital material lying on the surface of the 
Archean at the time when the Ordovician sea reached the level of the 
Archean plateau, so prominent in this neighbourhood. 
The Trenton formation—The Trenton formation about Quebec 
city has only been studied and recognized on the north shore of the St. 
Lawrence, and consists for the most part of thin and evenly bedded im- 
pure limestones and shales of a light gray colour, some beds semi-crys- 
talline in structure, others compact and fine-grained. As in almost 
every locality, the Trenton of Quebec is highly fossiliferous ; at the 
Beauport quarries, Montmorency Falls, both above and below, at Lor- 
ette, Templeman’s quarry, Charlesbourg, Pointe aux Trembles, this 
formation may be studied to advantage. 
Interesting lists of the fossil remains obtained by various officers 
of the Geological Survey from the Trenton formation of this district 
and examined by the writer, have been published in Mr. Low’s report 
on the geology of Portneuf, Quebec and Montmorency counties in Ann. 
Report, Geol. Survey of Canada, Vol. 5, pp. 34-45, 1890-91. 
In its greatest development, the Trenton probably measures not 
less than 450 to 500 feet in thickness. Among the more interesting 
fossil remains of this formation are Schizotreta Pelopea, Billings, Lingula 
riciniformis, Hall, Prasopora Selwyn, Nicholson, Conularia Trenton- 
ensis, Hall, Orthoceras Beauportense, Whiteaves, Hormotoma gracilis, 
Hall, Rafinesquina aiternata, Trinucleus concentricus, Eaton, Encrinurus 
vigilans, Hall. In many of the outcrops of the Trenton however about 
Quebee City its thickness is very small and does not exceed over one 
hundred feet. 
The Utica formation.—At Pointe aux Trembles, Charlesbourg, 
Montmorency Falls, and overlying the limestones of Beauport quarries 
there occur series of black or dark-brown, buff-coloured shales for the 
most part bituminous, which are eminently characteristic of the Utica 
formation of New York State, the province of Ontario, and other por- 
tions in eastern North America. 
Sir William Logan estimated the thickness of this formation to be 
318 feet, but one must confess that it is most difficult to know where to 
draw the line between the Utica and the Lorraine formations inasmuch 
as the shales of the one formation pass imperceptibly into the other. 
Among the characteristic fossil species of the Utica may be mentioned, 
Orthograptus quadrimucronatus, Hall, Leptobolus insignis, Hall, Schizo- 
crania filosa, Serpulites dissolutus, Billings, Conularia gracilis, Hall, 
Orthoceras tenuistriatum, Hall, Triarthrus Becki, Green, and Asaphus 
latimarginatus, Hall, (A. Canadensis, Chapman). 
