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2 • EUB/AGS Rock Walk 2004
A Rock Walk Through Downtown EdmontonA rock walk is a stroll along the sidewalks of downtownEdmonton and the opportunity to see the amazing suiteof minerals and rocks on display in the building stoneand rock materials of the city structures. The informationfor this rock walk was assembled through a comparisonwith similar rocks in hand, from other geologists andmasons, from referenced publications and, in a very fewcases, from the analysis of actual pieces of the buildingstone.
The following are some of the buildings and sites thatyou see as you do a rock walk through downtownEdmonton. The next time you are standing on the cornerwaiting for the lights to change, have a look at thebuilding near you.
Map of downtown Edmonton (not to scale) outlining some of thebuildings on the rock walk.
Very attractive,polished pinkgranite, tradename RosaSardo, is used forthe fountains andbenches in Canada Place (building number 1). Thegranite is composed of light grey quartz, large pink orflesh-coloured feldspars, white plagioclase feldspar andblack mafic minerals.
Fired granite is used on the walkways and the floor. Thesame fired granite is used on the outside sidewalk.
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The former Imperial Bank of Canada (number 2 on themap) first opened its doors at this site in 1891. In 1950,the building was demolished to build a larger structure.However, due to a shortage of structural steel,construction was delayed until 1952. You may note therelief panels, which show trains and planes, the metalspandrels with the bank’s logo, as well as the quoins andpilasters stylized as bands of rectangles. (HistoricalWalking Tours of Downtown Edmonton, 1995.)
The building stone and rock materials consist offossiliferous Indiana limestone and black granite. Theblack granite consists primarily of feldspar. A closer lookat the black granite will reveal brilliant flashes of blue asthe light changes on them.
A view of the southentrance to the buildingreveals the use of Indianalimestone and blackgranite (close-up of theblack granite with theblue crystals).
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Number 3 on the map is the Toronto-Dominion BankBuilding at 10004 Jasper Avenue. It is made with one ofthe world’s most common building stones—marble. Thisparticular building is made with Carrarra marble fromthe Carrara region in northwest Italy.
Marbles ofcommerce(rocks withthe tradename ofmarble)include true(geological)metamorphicmarble,polishableserpentinerocks (verdantique) and certain crystalline limestones. Carrarra is afine-grained marble with a mosaic of calcite crystals 0.1to 0.3 mm in size. The marble is 97% calcite with minorfeldspar and mica particles.
Pink and black granite are the dimension stones used forthe Empire Building, number 4 on the map. The pinkgranite is very coarse grained with large pink crystals offeldspar.
A much finer grained black granite is used on theentrance on the east end of the building. The history ofthe Empire Building is carved into this black granite.
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Cephalopods are represented very well in the rock.These are like modern squids or nautili. The ones with astraight shell are Orthocone cephalopods, and the oneswith a curved shell are Winnipegoceras.
True corals arewell representedin the rock aswell. The ‘chaincoral’ isappropriatelynamed. Upon acloser look, youwill see thepattern in therock is a seriesof interlinkedchains(Favosites).
The ‘horn coral’ is asolitary coral. In the rockthe fossil has a pattern oflines radiating out to anoval or horn-like pattern(Grewingka).
‘Sunflower coral’ istypical of TyndallLimestone. It is actuallyan alga. The fossil ischaracterized by auniform grid pattern and
a distinguishable deep hollow in the centre(Receptaculites).
Igneous, Metamorphic and Sedimentary
The corner of Jasper Avenue and 101 Street containsbuildings constructed with the three major rock types(igneous, metamorphic and sedimentary). The CIBC onthe northwest corner represents the sedimentary group asit is constructed with Tyndall limestone (Tyndall Stone).The Royal Bank on the southwest corner represents theigneous group as it is constructed using brown granite.The former Bank of Montreal on the southeast cornerrepresents the metamorphic type as it uses gneiss.
The building stone in the CIBC building (number 5) isTyndalllimestone.This limestoneis quarriedapproximately30 kmnortheast ofWinnipeg,Manitoba, atTyndall andGarson,Manitoba. Ithas been usedsince 1832(e.g., FortGarry).Tyndall Stoneis limestone (light colour) with dolomite (darker colour)in the irregularly shaped burrows of ancient marineworms. The limestone is 250 million years old (UpperOrdovician).
The outside of the building uses various cuts of theTyndall Limestone. A close-up look at the walls willreveal many interesting fossils embedded in them.
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Igneous rock is represented in the 6th building on the tour, theRoyal Bank building, consisting of brown granite (DakotaMahogany). This building stone is a medium-grained granite thatcan be brown, blue or pink depending on the light. The quartzcrystals look like blue ‘eyes’ in the rock.
The 7th building is the formerBank of Montreal building.Dimension stone slabs are cutfrom large blocks of MortonGneiss. This gneiss comes fromMinnesota and is believed to be3.6 billion years old. The largedimension stone panels arearranged to create a matchingpattern on the side of the building.Each slab is cut from a large blockand is usually less than 1/2 inchthick. The ‘flow’ of variousmaterials in the development ofthe gneiss is clearly visiblethroughout the panels on thebuilding.
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The outside facing entry of the Paladium Club, number8, is a soft travertine (spring deposit), probably fromBari, Italy. The rock is about 100 million years old. Itforms when algae grow in nutrient-rich pools and trapcalcite crystals to form layers. As the layers are buried,the algae suffocate, die and decompose, forming gasbubbles that are preserved as the holes you see betweenthe layers.
The holes in the travertine are plugged with epoxy tomake the rock more resistant to weathering.Occasionally you see rock with the holes left open.
In front of the boxoffice there is a redrock with a crest.This rock is redgranite and usesboth polished andunpolished granite.
Number 9 on the map, the Union Bank, is the only pre-World War I bank building remaining in downtownEdmonton. The facade of local pressed brick and Indianalimestone conceals a modern, fireproof, steel and brickstructure.
The surface onthe front of thebuilding isrough becausethe rock iscomposed ofsmall fossils.The rock ismade of themineral calciteand is quitesoft. Althoughthe rock is soft,it is tough, easyto saw andmakes a greatbuilding stone.Thislimestone isfound inmany ofEdmonton’solderbuildings.
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The Fairmont Hotel Macdonald (number 10) wasdesignated as a municipal historical resource by the Cityof Edmonton in 1985. The skeleton of the hotel is steeland reinforced concrete, which is hidden beneath a skinof Indiana limestone, granodiorite and sheet copperroofing. Throughout the interior of the building, in thefloors, walls and furniture, you may also see Carrarraand Lepanto marble, syenite (Blue Pearl) and gneiss.
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The Shaw Conference Centre, number 11 on the map, wasopened in June 1983. The building has more than 50 000yards of concrete and is bolted directly into the bedrock, asthis is the western edge of the 1901 Grierson Hill landslide.The most obvious rock in the building is a large, blue,tabular slab inside the Jasper Avenue entrance, by the pond.The blue mineral is sodalite and the rock is a syenite, a kindof ‘no quartz’ granite. It is composed of blue sodalite andlarge blebs of magnetite (metallic grey). The bench belowthe blue slab is made of a polished black rock with darkplagioclase feldspar and mafics. It is probably diorite.
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For further information on the full-size Geoscape EdmontonPoster or other AGS publications please contact
AGS Information SalesTel: (780) 422-3767 Information SalesFax:(780) 422-1918 Information SalesE-mail: [email protected]
Alberta Geological Survey main office4th Floor, Twin Atria Building
4999 - 98th AvenueEdmonton, Alberta,Canada T6B 2X3
Tel: (780) 422-1927http://www.ags.gov.ab.ca/
Alberta Geological Survey LibraryTel: (780) 427-4663
E-mail: [email protected]
AGS Mineral Core Research Facility (MCRF)Edmonton, AlbertaTel: (780) 466-1779
E-mail: [email protected]
