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Mount Royal

Small mountain in Montreal, Quebec, Canada

  • 11 min read
  • 8 chapters

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Through Montreal, Sedimentary rock and Erosion

The mountain is part of the Monteregian Hills situated between the Laurentians and the Appalachian Mountains. It gave its Latin name, Mons Regius, to the Monteregian chain. The mountain consists of three peaks: Colline de la Croix (or Mont Royal proper) at 233 m (764 ft), Colline d'Outremont (or Mount Murray, in the borough of Outremont) at 211 m (692 ft), and Westmount Summit at 201 m (659 ft) elevation above mean sea level.

Geology

Mount Royal is the deep extension of a vastly eroded ancient volcanic complex, which was probably active about 125 million years ago.

The hill, along with the other mountains of the Monteregian Hills, was formed when the North American Plate moved westward over the New England hotspot. By a process known as intrusion, magma intruded into the sedimentary rocks underneath the area, producing at least eight igneous stocks. The main rock type is a gabbro composed of pyroxene, olivine and variable amounts of plagioclase. During and after the main stage of intrusion, the gabbros and surrounding rocks were intruded by a series of volcanic dikes and sills. Subsequently, the surrounding softer sedimentary rock was eroded, leaving behind the resistant igneous rock that forms the hill.

The mineral montroyalite, discovered in Montreal, is named after the hill that provided the definition sample.

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