L'ANGE-GARDIEN QUARRY
This quarry is located South-west of l'Ange-Gardien municipality, approximately 50 km from Montreal, near the Appalachians.
The rocks found in this quarry are part of the St.Lawrence Lowlands area and date back to the Ordovician era. They were partly distorted (through folding and metamorphism) by the formation of the Appalachians, this mountain chain resulting from collisions between continents.
These rocks are limestones and black argillaceous slates.
Limestone rocks are sedimentary rocks formed in a tropical marine environment through precipitation, accumulation and direct cementation on the bottom of a basin. They can also contain fossil and seashell fragments from marine organisms.
Argillaceous slate is the product of a low-grade metamorphism of shale. Shale is a sedimentary rock formed through the accumulation and cementation of argillaceous sediments that settle on the bottom of a marine or lake basin. Metamorphism is a process by which a pre-existing, sedimentary rock or other kind of rock changes mineralogical composition and shape when subjected to high pressure and temperature. Therefore, shale is a soft, friable stone that becomes harder when metamorphized into argillaceous slate.
