Geology of Montreal.
Jul. 29th, 2004 02:41 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
swestrupI just came across a pdf of the Geology of Montreal. I find it makes interesting reading, if you have any curiosity about the rocks underfoot. One thing that I hadn't known, Mont Royal is NOT an extinct volcano, as I've always been told! It is, in fact, a pluton, caused by magma intrusion. In other words, a hot bubble of magma rose from some deep hotspot and tried to form a volcano. It never succeeded, but it did push a large column of rock up out of the ground during the attempt. The hills of Saint-Bruno, Saint-Hilaire, Rougement and Johnson are also of the same type and were probably all caused by a now inactive hot spot under the Saint Laurence somewhere.
On the other hand, Ile Saint Helen WAS the result of, if not a volcano, at least a "violent exhalation of magmatic gas", some 350 million years ago, long before Mount Royal was extruded.
On the other hand, Ile Saint Helen WAS the result of, if not a volcano, at least a "violent exhalation of magmatic gas", some 350 million years ago, long before Mount Royal was extruded.
