[Amr] GEOLOGY OF SOME CITIES IN EASTERN CANADA 157 
tinguished paleontologist, Elkanah Billings. Amongst the more 
conspicuous forms characterizing the Chazy of Montreal may be men- 
tioned the following:—Bolboporites Americanus, Malocystites Murchi- 
soni, Blastoidocrinus, carchariedens, Rhynchonella (Camarotechia) plena, 
Lingula Belli, Orthis (Hebertella) borealis, O. imperator, Bathyurus 
Angelini. 
Bird's Eye and Black River formation.—Dark gray, impure, fossilif- 
erous limestone for the most part thin-bedded, interstratified with 
earthy shales, constitute the strata which have been referred to this 
formation in the Montreal district and may be best studied at the Pointe 
Claire quarries, from which the huge blocks of limestone were obtained 
for the construction of the piers of the Victoria Tubular Bridge. Out- 
crops of this formation also occur at St. Vincent de Paul. 
This formation forms a narrow belt or zone of outcrop between 
the Chazy below and the Trenton formation above, and possibly no- 
where in this district does it exceed 100 feet in thickness. 
Many of the surfaces of the limestone beds at the Pointe Claire 
quarries exhibit large masses of corals and sponge-like organisms, be- 
sides numerous other types of marine organisms, amongst which the 
following are probably the most characteristic :—Tetradium fibratum, 
Columnaria Halli, Solenopora compacta, Stromatocervum rugosum, 
Helicotoma planulata, Cyrtodonta Huronensis, Bathyurus extans. 
The Trenton formation—As in other portions of Canada and North 
America where the Trenton formation occurs it is always proved to be 
both important from an economic standpoint and of great interest to 
geologists both on account of its remarkable uniformity and continuity 
as well as by its numerous fossil organic remains, which it has yielded. 
At the Mile End, Côte St. Louis and Côte St. Luc quarries from 
which such a vast amount of material has been extracted for building 
purposes, at Lachine, Hochelaga and Pointe aux Trembles, the Trenton 
formation, consisting of dark-gray and sometimes black, and light-gray 
fossiliferous limestones and shales, often fine-grained and compact, at 
other times semi-crystalline, is well developed. It is remarkably uni- 
form throughout its thickness which is in the neighbourhood of 450 
feet and forms the main mass of the surface rock, as at present exposed 
on the flanks of the intrusive mass of Mount Royal. 
The normal undisturbed position of the Trenton formation in the 
Montreal district is probably but a little above the level of the St. 
Lawrence river, along the harbour front. It appears, however, that 
enormous masses of the Trenton were caught up and lifted bodily, along 
with the subjacent strata, by the igneous mass of Mount Royal in the 
several eruptions, and were raised to the present level to which they 
