209 
[Marcou. 
1891.] 
The city of Quebec is built at the extremity of a sort of prom- 
ontory, extending from the mouth of the Charles river to Cape 
Rouge (pronounced Carouge by the French Canadians). This 
promontory is capped by a sort of plateau, more or less accidented 
by small hills, which begin behind the citadel and extend to Ste. 
Foye, St. Albans and Cape Rouge, bounded on the south by es- 
carpments like almost perpendicular cliffs on the St. Lawrence 
river, and on the north by another great escarpment called “C6te. 
Ste. Grenevidve,” “C6te de la N6gresse,” Cdte Sauvageau,” etc. 
The whole is an elongated mountain formed entirely by the Upper 
Taconic strata arranged in a fan-like structure (called structure 
en 6ventail by the French and Swiss geologists) very common in 
the Alps. It is the result of some strong lateral pressure, made 
upon rocks mainly slaty, but containing now and then lenticular 
masses of magnesian limestone, limited bands or spindles ( fus - 
eaux in French) of pudding limestone, conglomerate and even of 
sandstone, which being strongly squeezed north and south, was 
forced into folds, with a quantity of small, very local faults 
(called faillottes by French geologists) . All the folds strike more 
or less east- west ward with a deviation toward the north and south, 
just like the course of the St. Lawrence river, which very likely 
has followed some of the local folds in digging its bed into the 
slaty Taconic strata. 
The celebrated citadel of Quebec is built on the very top of the 
most important and largest of those folds ; and if looked at from 
the other side of the St. Lawrence, or from the middle of the 
stream, we see (fig. No. 5) a splendid arched fold wdth a long rise 
of the strata at the back of Champlain street, recalling the arched 
fold of the citadel of Besangon in Franche-comte (France). 
As I have said previously, the great masses of rocks are slates, 
varying in color from gray to blue, brown, black, red and green. 
But the slates contain inclosed beds, all more or less lenticular 
and limited in extent, of marly limestone, magnesian limestone 
very hard and almost sub-crystalline, pudding limestone, true 
conglomerate, and some small lenticular masses of magnesian 
limestone varying in size from an egg to a diameter of one or 
more yards. For instance in ascending the rue de la Montagne, 
just in the perpendicular cliff of the black slates, under the Sem- 
inary garden, a lenticular block of whitish magnesian limestone, 
PROCEEDINGS B. S. N. H. 
VOL. XXV. 
?4 
JAN. 1891 
