By:Jane Lang
Kitchener - Waterloo is in the unfortunate situation of having no natural outcrops of bedrock nearby. However, natural stone of a variety of types has been used as a building material at a number of locations in the twin cities.
Stop 1 - Rock Garden in the Quadrangle between the Earth Sciences-Chemistry and Math-Computer buildings on the University of Waterloo Campus.
These rocks have been collected by the Earth Sciences Museum from locations all over Ontario. They are well labelled as to type and original locality.
Stop 2 - Student Life Centre, University of Waterloo
Notice the floor in the enclosed foyers and on the main staircases inside the new wing. These rock slabs are made of slate which is a fined grained rock resulting from low grade metamorphism of a sedimentary, clay-rich rock called shale. With metamorphism, the original rock becomes harder and develops a pronounced "slaty cleavage" (the ability to break into thin flat pieces). These two properties make it an excellent choice for flooring tiles, roofing shingles, blackboards, and billiard tables. The greenish streaks in the rock are due to the presence of ferrous iron oxide, while the reddish colour is from ferric iron oxide.
Proceed across campus to the corner of Westmount and University Avenue. Walk south on Westmount to Father Bauer Drive. Turn left and proceed down Father Bauer Drive.
Stop 3 - Stone Block Wall along Father Bauer Drive across from Luther Village
These huge blocks of dolostone are used to shore up the embankment along the roadway and also to serve as a backdrop for the rock gardens. Dolostone is a sedimentary rock that usually originates as limestone when calcium carbonate precipitates from sea water with the aid of marine organisms. Over a long period of time, some of the calcium was replaced by magnesium, thus forming a slightly different rock type called dolostone. These blocks are similar to what we would see capping the Niagara Escarpment. The Niagara Escarpment owes its presence to the fact that the rocks forming it are much more resistant to erosion than the shales to the east of the escarpment
Notice the very "vuggy " nature of these particular blocks. The many cavities in the rocks serve as locations where crystals can precipitate out in an unimpeded fashion, producing crystal shapes. Crystals of calcite, dolomite and gypsum (variety selenite) can be found in these vugs. (Please leave them intact!) Continue down Fr. Bauer Drive to Erb Street. Follow Erb Street to the corner of Erb and Albert Streets.
Stop 4 - Marsland Centre, corner of Erb and Albert Streets
Look closely at the reddish slabs of rock on the outside of the building. This building was actually built in two stages. In the newer section the slabs are really a "fake" rock in which crushed rock particles are put into a cement, dyed, then cut and polished. The older section, from a few feet away, appears to be made of the same material of the same or similar colour. Upon close inspection however, it turns out to be composed of polished red granite. Granite is an igneous rock which cools from a molten magma underground. The term "granite" in common usage has come to mean any coarse grained igneous rock. However, the geological definition of granite specifies that the rock must have at least 10% quartz grains and that at least 2/3 of the feldspar mineral grains must be potassium feldspar (instead of plagioclase feldspar). Since potassium feldspar is usually either pink or light grey, most true granites will also exhibit variations of these colours.
Enter the foyer of the building and notice the tan slabs of rock on the walls near the elevators. This is a porous rock called travertine. Its sedimentary nature is evident in the layered structure easily seen in the slabs. Travertine is formed from calcium carbonate that precipitates out of groundwater in caves or at hot springs. Because it has the same chemical composition as limestone, travertine is often classified as a subcategory of limestone.
Cross Dupont Street to the Waterloo Public Library.
Stop 5 - Waterloo Public Library
Look closely at the rocks composing the outside of this building. Although there appears to be a variety of colours of rocks here, most can be classified as one rock type called gneiss (pronounced "nice"). Gneiss is a coarse grained metamorphic rock which has a distinct foliation (layering) of its light and dark minerals. The light coloured minerals are mostly feldspar, quartz and muscovite mica; while the darker bands are mostly composed of biotite mica and/or hornblende. The mica minerals are the very "platey" ones which will reflect light extremely well and therefore "sparkle" if viewed from the correct angle. Gneiss is formed from medium to high grade metamorphism of either: granitic rocks; or clay and quartz rich sedimentary rocks.
Proceed down Dupont Street to King Street
Stop 6 - Old Post Office Building/Time Square, Northwest corner of Dupont and King Streets
The blocks on the bottom half of this building are made of sandstone, which is a sedimentary rock composed of "sand-sized" grains. These grains have been eroded from pre-existing rocks, then transported and deposited in a beach, shallow marine, or desert type of environment. Because the mineral quartz is very resistant to both mechanical and chemical weathering, it tends to be the predominant mineral type in sandstones. The quartz grains in these blocks have been naturally stained with an iron oxide called hematite which gives them a red colour. The sandy texture of the blocks can be felt by rubbing your finger tips along the rock surfaces. This red type of sandstone can be found at several localities in south-western Ontario.
Proceed south down King Street.
Stop 7 - CIBC Building, #27 King Street North
Observe the "Greek-style" portico at the entrance to this building. It is made of limestone which, as mentioned earlier, is a sedimentary rock composed of calcium carbonate. As every student of geology knows, limestone dissolves readily in acid - even a weak one. (This is a common test in geology labs to identify limestone.) If you look carefully at the fluted columns on this structure, you can see the damage that acid rain has done to some of the sections.
Stop 8 - #23 King Street North
Look carefully at the store front of this building. The "rock" here is actually artificially - produced to have the appearance of sandstone.
Stop 9 - Bank of Montreal (the Molsons Bank Building), Southwest corner of King and Erb Streets
The blocks on this building are made of a tan coloured quartz sandstone. The grain size is slightly finer than that found in the sandstone at the Old Post Office building up the street - so you will have to look carefully in order to see its "sandy" texture. The surfaces of these blocks have been artificially "pitted" to impart an interesting textural appearance. This texture slowly disappears with time however. Notice the difference between the rate of weathering of this building and that of the CIBC building up the street. Because sandstones are composed predominantly of stable quartz grains, they are usually relatively resistant to weathering and therefore desirable as exterior building material.
Cross King Street at Erb and continue down King Street.
Stop 10 - Frank's Jewellers, #8 King Street South
Notice the polished black stone on the exterior of this store front. This rock is commonly called "black granite" but is more correctly named anorthosite. Like granite, anorthosite is a coarse grained igneous rock but it is composed almost entirely of one mineral - a calcium rich plagioclase feldspar. Anorthosite belongs to a group of "basic" igneous rocks that are formed from minerals that crystallize at a much higher temperature and include minerals formed of elements which react to weathering more quickly than than those making up light coloured igneous rocks such as granite (see the Bowen's Reaction Series figure on page 6).
Continue down King Street.
Stop 11 - Uptown Parkade, King Street South
Notice the large boulders and cobblestones at the front of this building and look carefully at their texture. The photograph (right) clearly shows that these are not naturally formed rocks. Continue down King Street, turn left at Willis Way, then cross Regina Street at Willis Way.
Stop 12 - Waterloo City Centre, 100 Regina Street South (Northeast corner of Regina and William Streets)
Walk inside this building and take particular note of the striking floor tiles. These tiles have been manufactured to have the appearance of sedimentary breccia. Breccias are rocks that contain pebble sized angular fragments in a finer grained matrix. The angular nature of the fragments indicate that the particles have not travelled far from their point of origin before being consolidated into a rock. This "man made" version contains genuine rock fragments of serpentinite, marble and travertine (among others); however, the cementing has been artificially done.
Proceed up William Street and cross at King Street.
Stop 13 - First United Church, Northwest corner of King and William Streets
By now the texture in this stone should begin to look familiar. Its sedimentary origins are evident in its compositional layering. Its sandy nature can be felt with the finger tips. The variations in colours of these sandstone blocks are due to the presence or absence of varying types of iron oxides.
Proceed down King Street to Kitchener
The two-colour appearance on the surface of this building is created by the differences between polished and rough cut stone. The polished sections have a darker appearance than the unpolished sections, yet both are made of the same granite. Look closely at the texture in the stone. You will notice that it contains very large pink potassium feldspar crystals surrounded by a finer grained matrix. This texture is called porphyritic and is indicative of a two stage cooling process in the formation of the rock. The rock type is referred to as "granite porphyry".
Enter the foyer of the building and observe the rock slabs on the walls. Notice that the rock consists of large angular, grey fragments in a tan coloured matrix. The fragments are pieces of marble. To most people, the term marble refers to any rock with coloured streaks in it. However, to a geologist, it refers to a recrystallized or metamorphosed limestone (or dolostone). This rock type as a whole would be referred to as a marble breccia because the original rock has been broken into large angular fragments which were later cemented together.
Cross King Street and proceed east on King.
Stop 15 - Kitchener City Hall
A variety of rock types has been used in the making of this building with interesting effects. The most notable stone here is the striking red sandstone forming the outside walls of the building. These rock slabs were imported all the way from India. Sections of the floor inside the main floor rotunda are made of the same rock type as the patio stones and the staircases inside and outside the building. Notice how the appearance of this coarsely crystalline grey granite changes with polishing. The majority of the flooring slabs in the foyer are black anorthosite.
Stop 16 - Scotia Bank, #64 King Street, Kitchener (King and Ontario Streets)
This building is composed of dark green "frames" outlining white marble slabs on the exterior walls. The dark green rock is a metamorphic rock called serpentinite. It is composed of essentially of one mineral - serpentine - which forms as an alteration product of the minerals olivine and/or pyroxene. Since both of these minerals are commonly found in "ultrabasic" igneous rocks, the origin of serpentinite is usually low to medium grade metamorphism of ultrabasic (or silica deficient) igneous rocks. The mineral serpentine also comes in a fibrous variety which is commonly known as asbestos.
Stop 17 - Canada Trust Building, 55 King Street, Kitchener (King and Ontario Streets)
Notice the blue-grey "pillars" attached to this building that extend upwards only about one meter from the ground. This rock is composed of the mineral labradorite - which is a type of calcium rich plagioclase. If you look closely at this mineral from the correct angle, you will notice that it has an unusual property. The interference of light rays (refracting from closely spaced planes inside the labradorite crystals) gives it a blue - green iridescence. This property can make the mineral valued as a gemstone. The mineral name comes from the fact that there is a well known occurrence of it near Nain on the coast of Labrador.
The walls outside and inside this building are composed of blocks of a grey, porphyritic granite, with both polished and unpolished sections. (See natural Labradorite in the university rock garden).
Inside the foyer of this building, the patterned flooring is composed of cut and polished sections of three different rock types: a salmon-pink granite, a white-grey granite, and a black anorthosite.
Stop 18 - #67 King Street E. (corner of King and Benton Streets)
The outside walls of this building are made of a tan and grey limestone from Manitoba with an unusual texture in it. The rock is called Tyndall Stone and its "mottled" texture is the result of the burrows of marine animals. Burrows or other tracks and trails left by living organisms are known as trace fossils. Other fossils such as gas tropods and corals can also be seen in this Tyndall Stone. This rock type is well known to many because it is used extensively in the Parliament buildings in Ottawa.