Earth Cache Story: The Rocks of the Credit Foncier Building
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To log this EarthCache, please send your answers to the following questions within 4 days of posting your found log. Please make sure you do not include any photos that reveal answers to the questions directly in your log.
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Mottled Burrows: Take a photo of you or a group member pointing to one of the burrows in the stone (using your finger or pen for scale).
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Do the burrows appear darker and more resistant to weathering compared to the surrounding lighter limestone?
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Identifying Fossils: Find two more types of fossils from the examples provided in the cache page, such as:
- Gastropods (snails or slugs)
- Corals (either solitary or colonial)
- Cephalopods (such as orthocones)
- Stromatolites
Take a photo of at least two types of fossils and send them in, identifying which fossils you have found.
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Geological Time Period: From the cache page, identify which geological time period Tyndall Stone comes from, and approximately how many years ago it started to form. (Hint: This stone was formed during the Ordovician Period.)
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Now for a bit of fun! How many different kinds of fossils can you find and for a brain teaser can you discover their fossil names by comparing them to pictures in the description?
DO NOT POST ANSWERS IN YOUR LOG. Please don’t provide the answers when logging the cache online except for the photo, for the rest of the queries use the “Send answers” feature OR geocache mail the cache owner including the earth cache GC number, title and the answers. 
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Earth Cache Story: The Rocks of the Credit Foncier Building
Did you know that the stones used to build some of our city’s most famous buildings have a lot of history in them? One such building is the Credit Foncier Building, built in 1911 in Regina. Have you ever looked closely at the beautiful buildings around you and wondered what materials were used to build them? This building, which stands proudly on 12th Avenue, is made of a special kind of rock called Tyndall Stone®. Tyndall Stone is not just any rock—it’s a piece of ancient Earth that tells a fascinating story of life millions of years ago.
EarthCache: The Fossils and Geology of Tyndall Stone – The Credit Foncier Building
Welcome to an exciting geological journey through the Credit Foncier Building, where the very walls of this architectural gem are a living, fossilized record of ancient marine life. The building is constructed from Tyndall Stone, an extraordinary limestone quarried from the Garson region of Manitoba, Canada. This is not just a stone, but a time capsule that tells the story of life over 450 million years ago during the Late Ordovician Period.
Tyndall Stone's signature feature is its mottled appearance, formed by a combination of trace fossils and body fossils that make it an essential part of Canada's architectural history. The stone has been used in significant landmarks like the Houses of Parliament in Ottawa, the Empress Hotel in Victoria, and the Legislative Buildings in Winnipeg. But here, at the Credit Foncier Building, the stone’s fossils are part of the structure you can explore firsthand.
What Makes Tyndall Stone Unique?
Tyndall Stone is a fine-grained, cream-colored limestone with darker, dolomitic mottling. The mottles are formed by the trace fossils, which are preserved burrows left by ancient marine creatures. These creatures burrowed through soft, muddy seabeds, and over time, their burrows became filled with dolomite, creating the darker patterns we see today. Tyndall Stone is fossil-rich, and it showcases a variety of organisms from an ancient ocean that existed just south of the equator.
The Geological Context:
During the Late Ordovician Period, this area was submerged under a warm, shallow inland sea. The organisms that lived in this sea, including corals, gastropods, cephalopods, and stromatolites, left behind fossils that now make up the stone. Some of these creatures, like the orthocones (straight-shelled cephalopods), are ancestors of modern squid and octopuses. Fossils of colonial corals and gastropods (like snails) add further diversity to the fossil record.
The stone's mottling, which makes it resemble a tapestry, is caused by the differing hardness and chemistry of the burrowed sediments. Over time, dolomite-rich waters replaced the sediment in the burrows, creating a contrast between the darker mottles and the surrounding limestone. This transformation is what gives Tyndall Stone its distinctive, natural beauty.
Fossils Found in Tyndall Stone:
The fossils within Tyndall Stone represent a diverse marine ecosystem that lived around 450 million years ago. These creatures, preserved in the stone, give us insight into the environmental conditions of the ancient seas. Here's a breakdown of the key fossils found in Tyndall Stone:
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Trace Fossils (Mottling and Burrows): These are fossilized tracks, trails, or burrows created by ancient marine animals. The darker, mottled appearance of Tyndall Stone is caused by dolomite replacing the original sediment in these burrows. While the exact identity of the burrowing organisms is unknown, these marks are an essential feature of the stone.
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Corals (Tabulate and Rugose): Fossils of corals such as Catenipora (chain coral) and Grewingkia (horn coral) are common in Tyndall Stone. These are both extinct corals from ancient oceans. Tabulate corals are colonial and form long, slender tubes, while Rugose corals are typically solitary with a horn-shaped appearance.
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Gastropods (Snails and Slugs): Gastropods, or snails, are abundant in Tyndall Stone. Fossils of their spirally coiled shells can be found in various sizes. These organisms thrived in the ancient seas, and their preserved shells are a prominent feature of the stone.
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Cephalopods (Orthocones): Orthocones, the straight-shelled ancestors of modern cephalopods (like squid and octopuses), are found in Tyndall Stone. These fossils are long and cone-shaped, and represent a group of nautiloid mollusks that lived in the warm Ordovician seas.
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Stromatolites: Stromatolites are layered structures formed by the trapping of sediment by microbial mats, particularly algae. These structures are some of the oldest fossils on Earth, and the ones found in Tyndall Stone offer a glimpse into the early stages of life on Earth.
The Geological Significance of Tyndall Stone:
The fossils in Tyndall Stone tell a story of an ancient shallow tropical sea, teeming with marine life, just south of the equator. The stone preserves the trace fossils of creatures that burrowed in the soft sea floor, leaving their marks for millions of years. It also contains the remains of corals, gastropods, and cephalopods, all of which offer insights into the biodiversity of the Ordovician Period.
The geological processes that formed Tyndall Stone — from the deposition of limey sediments to the percolation of dolomite through ancient burrows — reflect the changing environmental conditions of the time. The burrows and mottling in Tyndall Stone give us clues about the habitat of ancient marine life, while the body fossils provide direct evidence of the organisms that once lived in the waters of southern Manitoba.
By exploring these fossils, you’re taking a step back in time to a world where oceans teemed with life, and the landscape was shaped by burrowing organisms and the slow process of fossilization. The Credit Foncier Building, with its Tyndall Stone façade, offers a living lesson in ancient geology — a time capsule etched in stone.
Enjoy your journey, and feel free to share any additional fossil discoveries you make along the way!
The Credit Foncier Building, with its walls made of Tyndall Stone, stands as a reminder of the Earth’s ancient past. It’s a piece of history carved in stone that we can see and touch today! Now you know a little bit about the fascinating story behind the Credit Foncier Building’s stones. Rocks like Tyndall Stone are not just pretty—they are history!
Bibliography (or for more information if you love Tyndall Stone geology):
- Adventures for Wilderness. "Tyndall Stone: A Geologic Treasure." Adventures for Wilderness, 2021, https://www.adventuresforwilderness.ca/wp-content/uploads/2021/03/20201200_apsbulletin_tyndall_stone_tkoning.pdf.
- Brandon University. Tyndall Stone Brochure. May 2023, https://www.brandonu.ca/geology/files/2023/05/Tyndall-Stone-Brochure.pdf.
- CBC News. "Manitoba’s Tyndall Stone Receives Global Heritage Designation." CBC News, 29 March 2023, https://www.cbc.ca/news/canada/manitoba/manitoba-tyndall-stone-global-heritage-designation-1.6724169.
- CTV News. "Stone Quarried Only in Manitoba Receives International Heritage Recognition." CTV News, 30 March 2023, https://www.ctvnews.ca/winnipeg/article/stone-quarried-only-in-manitoba-receives-international-heritage-recognition/.
- Geocaching. "GC12TPF – A Geocache Adventure." Geocaching.com, https://www.geocaching.com/geocache/GC12TPF.
- Geocaching. "GC2F770 – Exploring the Tyndall Stone." Geocaching.com, https://www.geocaching.com/geocache/GC2F770.
- Geocaching. "GC96682 – Discovering Tyndall Stone." Geocaching.com, https://www.geocaching.com/geocache/GC96682.
- International Union of Geological Sciences. "Tyndall Stone: Geoheritage Stones." IUGS Geoheritage, https://iugs-geoheritage.org/geoheritage_stones/tyndall-stone/.
- University of Waterloo. "Manitoba’s Tyndall Stone: A Geological Marvel." Waterloo Earth Sciences, https://uwaterloo.ca/wat-on-earth/news/manitobas-tyndall-stone.
- University of Waterloo. "Peter Russell Rock Garden: Tyndall Stone." University of Waterloo Earth Sciences Museum, https://uwaterloo.ca/earth-sciences-museum/peter-russell-rock-garden/63-tyndall-stone-dolomitic-limestone.
- University of Saskatchewan. "USask Paleontologist Helps Stone Featuring Fossils Achieve Global Heritage Status." University of Saskatchewan News, 2023, https://news.usask.ca/articles/people/2023/usask-paleontologist-helps-stone-featuring-fossils-achieve-global-heritage-status.php.