This Earthcache can be completed from the sidewalk, no need to go up any steps or ramp. There is no physical cache here, in order to log a find, you must submit answers to the questions below. Street parking is available. All photographs on this cache page were taken at the EC location.
Posted coordinates will take you to the beginning of your quest to explore the wonderful world of fossils! Enjoy yourself and have fun while you imagine what life could have been like 445 million years ago!
History and Geology of Tyndall Limestone:
Tyndall Limestone is unique in its colour, beauty, strength and durability. It is used extensively as an ornamental building stone across Canada. It is quarried from the Selkirk Member of the Ordovician Red River Formation in the vicinity of Garson and Tyndall, Manitoba. It is Late Ordovician in age and was formed from sediments laid down in a shallow tropical sea approximately 445 million years ago. It was first used in 1832 for building Lower Fort Garry and has since become popular for bulding purposes through Canada and the United States.
Tyndall Limestone is a fine-grained, cream-coloured, fossil-bearing limestone with a darker brown coloured tubular-shaped branching network of dolomitic limestone, which gives the rock a 'mottled' appearance. The mottling gives the rock a tapestry-like effect. Since it is highly fossiliferous, the fossils contribute to its appeal.
Two main types of fossils occur in Tyndall Stone. The first are trace fossils that occur as a pervasive network of burrows. The second type are body fossils, the calcite shells of a variety of marine animals and plants that lie dispersed through the rock.
Trace Fossils:
Trace fossils make this limestone an attractive building stone. They are the darker, fossilized tracks, trails, or burrows left during the day-to-day life activities of an organism found on a Tyndall Stone face. The mottling results from burrowing by marine creatures that occurred during and shortly after limestone deposition.
Burrows on Sea Bed
Burrows/Trace Fossils
Body Fossils:
Body fossils are the physical, shelled remains of organisms preserved by fossilization. Tyndall Stone is notable for its rich variety of large, well preserved body fossils. Some of the fossils found in Tyndall Stone are:
Gastropods - Commonly known as snails and slugs.
Gastropod
Cephalopods - Are molluscan animals that live in the sea.have a shell composed of a series of separate chambers, the group to which present day squids and octopuses belong. The inside of the fossil cephalopod shells are very similar to the internal parts of the modern Nautilus, a squid-like animal with a coiled shell, but straight ones are much more commonly seen in Tyndall Stone.
Cephalopod
Horn Coral (Grewingka) - is a solitary coral. In the rock, the fossil has a pattern of line radiating out to an oval or horn-like pattern.
Grewingka
Fisherites - A large form which 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.
Fisherite
To log this cache please submit answers to the following:
(Answers must be submitted before logging a find on this earthcache. You can write a note that you visited and change your log to 'found' once the answers are submitted and photo uploaded).
From write-up:
1) What year was Tyndall Stone first used to build Lower Fort Garry?
2) What 2 main types of fossils are found in Tyndall Stone?
From your observations of the building:
3) As you walk along these 'walls of fossils' take a photo (or several) of a fossil with your GPS (or thumb, or a coin, etc) for scale and try to identify it and post it with your log as proof of your visit. There are many, many fossils here that are not listed (and many tiny ones), please feel free to add a photo (or several) and its name if you know it (or just add the photo anyway).
4 a) At Virtual Stage 2 (N43 06.390 W79 04.020) on St. Clair Street, look for the distinctive fossil below the window and measure the width of this fossil.
b) What type of fossil do you think it is?
5) At Virtual Stage 3 (N43 06.381 W79 4.020) on St. Clair Street, choose one of the squares below the 'St. Andrew's' sign and estimate the average thickness of the burrows.
Since this is my first published Earthcache, kind suggestions are welcome.
References:
en.wikipedia.org/wiki/Tyndall_stone
en.wikipedia.org/wiki/Gatropoda
dfp.mediacooks.com/fossils
CONGRATULATIONS TO SAGARIES FOR A CHILLY FTF!!