Located in downtown Windsor you can find the former Dominion Building, now named Edifice Paul Martin Building, renamed for Paul Martin Senior, a former Windsor member of Parliament.   The building is located on the west side of Ouellette Ave between Pit Street and Chatham Street, one block south of Riverside Drive and the Windsor waterfront.  This building is a beautiful, 6 story Art Deco building fronted by a beautiful limestone façade that over time and erosion, fell into decay, and was repaired in 2017 to protect and preserve this wonderful and beautiful building.    Built in 1934 by George Masson and Hugh P Sheppard, the building has housed Canada Post, the Canada Revenue Agency and the Canadian Border Services Agency. 

Geology

Tyndall Stone, also called “Tapestry stone” is a distinctive mottled stone used in the construction or facing of many major buildings in Canada.  The Houses of Parliament in Ottawa, the Legislative Buildings in Winnipeg (Manitoba), Regina (Saskatchewan) and the Empress Hotel in Victoria BC are prime examples.  The material when fresh, is light grey with darker grey to brown mottles, and it weathers over time to a pleasant creamy yellow or gold colour with rust coloured mottles.  Fossils are always present in Tyndall Stone.

Tyndall Stone is quarried from Garson, Manitoba, which is located 37 km northeast of Winnipeg.  The Garson deposit was opened in 1895, although the first record of construction with Tyndall Stone extends even further back to 1832, when it was used to build the fort warehouse and walls of Lower Fort Garry in Manitoba.  Tyndall Stone acquired its name from Tyndall, the closest railway point to Garson.

During the late Ordovician Period, approximately 450 million years ago, southern Manitoba was a warm, shallow, inland sea just south of the equator.  Many different types of animals lived in this ocean including corals, sponges, molluscs and algae.  Other animals such as trilobites, and stromatoporoids are now extinct.  These creatures lived on or above the soft muddy sea floor and when they died, their skeletal remains became part of the muddy layers.  Other animals burrowed in the mud of the sea floor for food or protection and it is their preserved burrows that make up the beautiful mottling which gives Tyndall Stone its unique appearance.

A variety of fossil types can be found in Tyndall Stone.  This earthcache will identify some of the types.

Trace Fossils:  This is the name of the mottles which give the Tyndall Stone its distinctive appearance.  The mottles are actually fossils.  They are traces of burrows made in the original sediment by an unknown animal and the disturbed sediment within the burrows has been preferentially dolomitized at a later date making it darker and more resistant to weathering.

There is a noticeable colour difference between the mottle and the limestone surrounding it, as the mottles are mostly composed of finely crystalline dolomite (CaMg(CO3)2), and the surrounding rock is mostly limestone composed of calcite (CaC03).    You should notice that the trace fossils or burrows are darker in colour than the surrounding rock, and on the outer exposed surface of the stones, these dolomite mottles are more resistant to erosion.

Types of Fossils

Tabulate and Rugose corals were ancient types not related to modern corals. They are now extinct.

Chain Coral (Catenipora) was a colonial tabulate coral. Individual corallites which form the colony grew as a vertical tube with an elliptical cross-section and joined along the edges to give the appearance of a chain, hence the common name Chain Coral.

Saffordophyllum was a colonial tabulate coral in which the vertical tubes of the corallites are polygonal in cross-section and joined on all sides to give the appearance of a honeycomb, hence the common name Honeycomb Coral.

Calapoecia was a colonial tabulate coral in which the vertical tubes of the corallites are separated from each other by a calcareous mesh.

Grewingkia was a solitary rugose coral. Individuals were separate and grew in the shape of a slightly curved cone rather like a cow's horn, hence the common name Horn Coral. In cross-section, the fossil shows a circular to elliptical shape with septa radiating from the centre. In vertical section it shows an elongated curved triangular shape with septa running along its length.

Receptaculitids were animals with a similar life style to modern sponges. They are now extinct.   Fisherites were a large form that grew in the shape of a hollow irregular sphere, the walls of which were double and made up of small hexagonal plates and rods. In some sections the arrangement of the plates resembles a sunflower blossom hence the common, but erroneous name, Sunflower Coral.

Gastropods  include your typical snails, as well as other forms such as slugs. Fossils of both tall spiral shells and more broadly rounded ones may be found in Tyndall Stone.  Examples include the Hormotoma and Maclurites

Cephalopods: These are relatives of today’s octopods, squids, and the “living fossil” nautilus. Like the existing nautilus they have a shell composed of a series of separate chambers. The shell may be curved (like the nautilus) or straight, but straight ones are much more commonly seen in Tyndall Stone.

Logging Requirements

To Log this Earthcache

Please send me your answers within 4 days of posting your found log. If there is more than one cacher in your party, include the names in your group. Only one person needs to send me the group answers. No spoiler photos, please. Found logs posted without proof you visited the site will be deleted.

Questions

 Start at the northwest corner of Ouellette Ave and Pitt Street. Walk between the posted coordinates and the second waypoint and look for fossils along the front façade of the building as well as along the front of the building facing Chatham Street.  (Note: Signal bounce may be an issue so follow the directions in the hint.  Most of the fossils I identified were in the lower set of blocks in the light-coloured Tyndall stone, above the black layer of stone at street level.  One or two large fossils can be spotted in the second layer of blocks.  Proceed to the south end of the building at the corner of Ouellette Ave and Chatham Street.  Also, check out the south side of the building facing Chatham Street as the largest fossil was spotted on that wall.

Note:  There are some photos in the Gallery that narrow down some places to spot fossils.

1.    Take a photo of you or a group member pointing to a burrow using your finger or pen.  Send me this photo with your answers.   You can take this photo anywhere along the façade.    Do the burrows look like they are withstanding erosion and weathering compared to the lighter coloured limestone?

2.    Find two more fossils from the examples provided on the cache page.   Send me two photos and identify which fossils you found. 

3.    Do you see any small body fossils, for example, the remains of shells, stems, or coral? These many be small dime size pieces either complete or broken?  

4.   From the cache page, what geologic time period does Tyndall stone come from, and how many years ago was did it start to form?

5.    Please add an original photo of you at the cache location to show you were there.  You can add a photo of a fossil you found but do not identify it in your photo. 

To help narrow your search, I have added 2 photos in the Gallery showing locations I spotted good size fossils.

Resources

https://manitobamuseum.ca/main/the-fossils-surround-us/

https://tyndallstone.com/about-us/geographical-and-physical-findings

https://uwaterloo.ca/wat-on-earth/news/manitobas-tyndall-stone

Congratulations to Kawnupaddler for being the first to visit and getting FTF.