Heritage Stone 9. Tyndall Stone, Canada’s First Global Heritage Stone Resource: Geology, Paleontology, Ichnology and Architecture

Tyndall Stone is a distinctively mottled and strikingly fossiliferous dolomitic limestone that has been widely used for over century in Canada, especially the Prairie Provinces. It comprises 6–8 m within lower part of 43 thick Selkirk Member Red River Formation, Late Ordovician (Katian) age. quarried exclusively at Garson, Manitoba, 37 km northeast Winnipeg, since about 1895, past half-century extraction carried out solely by Gillis Quarries Ltd. The upper beds tend to be more buff-coloured than grey beds, as result groundwater weathering. Stone, mostly with smooth or sawn finish, put wide variety uses, including exterior interior cladding coursed random ashlar, window casements doorways. Split face finish ashlar using varicoloured blocks split along stylolites have become popular commercial residential buildings, respectively. lends itself carving well, being columns, coats arms sculptures. Many prominent buildings constructed provincial legislative Saskatchewan Centre Block House Commons Ottawa, courthouses, land titles post offices other public train stations, banks, churches, department stores, museums, office university buildings. These exhibit architectural styles, from Beaux Arts Art Deco, Châteauesque Brutalist. Canadian Museum History Human Rights are two notable Expressionist massive consists bioturbated, bioclastic wackestone packstone, rich crinoid ossicles. was deposited low-energy marine environment photic zone, on present-day eastern side shallow Williston Basin, which vast equatorial epicontinental sea covered much Laurentia time. Scattered thin grainstone lenses record episodic, higher energy events. spectacularly fossiliferous, slabs bearing fossils increasingly popular. most common macrofossils receptaculitids, followed corals, stromatoporoid sponges, nautiloid cephalopods, gastropods. relative abundance varies stratigraphically, suggesting subtle environmental changes took place distinctive mottles—‘tapestry’ trade—have regarded dolomitized burrows assigned Thalassinoides long thought networks galleries likely made arthropods. In detail, however, muddy sediment underwent protracted history bioturbation, large were horizontal back-filled features never empty. They can Planolites. matrix filling them overprinted several generations smaller tubular referrable Palaeophycus due their laminated wall linings. Dolomite replaced interiors larger well surrounding during burial, why mottling so variable shape.