Geology

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Lanark County straddles two distinct geological environments:
- To the west and north, the edge of the Canadian Shield (marble, granite and gneiss predominantly);
- To the south and east, sedimentary outliers of the Saint-Lawrence Lowlands (sandstone, limestone, and shale). On top of this lies a thin veneer of glacial debris and unconsolidated post-glacial sediments.
- While every geological setting is unique, the portion of the Shield that is represented in Lanark County is part of what is known as the Central Metasedimentary Belt of Grenville Geological Province - one of the most unusual, diverse and highly studied formations in the world (although perhaps one of the least understood).
- These rocks were formed roughly one billion years ago when two continents collided to form a vast mountain range that would have rivalled today's Himalayas.
- Over the next 800 million years, the Grenville Mountains were levelled by erosion, inundated by tropical seas, scraped bare by glaciers, and flooded by the icy waters of the Atlantic.
- Perth GeoHistory Booklet
Central to the Perth Museum's geological holdings is the historic collection of Dr. James Wilson of Perth (1798-1881). |
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The Perth Museum has changed location and focus over the years, but Archibald Campbell would surely be glad to know that the geological holdings he amassed are still being celebrated today. |
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Although entirely coincidental, it is enormously serendipitous that the geological collection of Dr. Wilson should come to reside within the walls of Matheson House. |
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Wilson & Matheson may have been the first to exploit the economic potential of the large deposits of mica and apatite in the area, but they were certainly not the last. |
![]() There are a number of specimens in the rest of the collection from outside Lanark County. Although the Museum's current mandate is to focus on and preserve our local heritage, the scientific and historical significance of Wilson's collection is undeniable and must be maintained in its entirety. There are also many fine specimens in our collection from other parts of the Ontario's Highlands region, which is largely defined by a single geological environment - the Central Metasedimentary Belt. These specimens can be viewed as being representative of Lanark County geology, but we also hope that these pieces will serve to inspire you to follow in the footsteps of Dr. Wilson and continue to explore the untapped potential for discovery that still exists here. |
Become a Part of "The Rock Cycle" in Perth! |
From the geoheritage displays at Civitan Court and Matheson House, which celebrate the foundation of Lanark County and the contribution of pioneering citizen scientists like Dr. James Wilson, to the discovery location for an intriguing rock type named after the town of Perth and an underground mine tour at Murphys Point Provincial Park, the Rock Cycle loop will give you a new appreciation of Ontario's Highlands unique heritage - our Geoheritage. |
Find out more at Perth Museum |
Visit Perth Museum to see a sample of the collection and to learn more. |