THE SITES BUILDING STONES AND FOSSILS The Tour stone) or when fossil corals and This walking tour covers 14 build- shells accumulate to form lime- ings in the downtown core of stone (e.g. Montreal limestone). Montreal. You can start the tour If fossil shells are visible in layers anywhere on the map, you don’t in the rocks it indicates that the have to walk in any order. This limestone was deposited in warm, is a much shorter version of the shallow seas. publication What Building Stones Tell, available in both French and Metamorphic: Rock that has been English at the Redpath Museum. changed (metamorphosed) by changes in heat and pressure. Each building on the tour features Under pressure, original features different types of rocks and fos- in these rocks are often deformed sils. You will examine some of or partially destroyed. Examples North America’s most attractive of metamorphic rocks are marble, and interesting rocks dating from ironstone, slate and quartzite. a period in the earth’s history more than a billion years ago. Choosing Building Stones Building stone needs to look attrac- Kinds of Building Stones tive and last for many decades, if not centuries. The stone must Igneous: Rock formed from cool- be strong enough to support the ing and solidification of hot mol- building above it and durable ten material (magma) such as enough to withstand attack by granite or syenite. Individual min- rain, sun, organisms, pollution or eral crystals such as quartz, feld- sea spray. Incompatible stones like spar and mica are easily identified sandstone and limestone would on polished granite surfaces. not be placed together, as acid solutions that wash carbonates 1 Redpath Museum 9 Musée des Beaux-Arts Sedimentary: Rock produced from the limestone can chemically 2 McGill Faculty Club 10 Maison Peter Lyall when particles such as sand are affect the durability of sandstone. 3 CIBC Building 11 Dominion Square Building laid down under water (e.g. sand- 4 Atholston House 12 Sunlife Building 5 Mount Royal Club 13 Cathédrale Marie-Reine-du- 6 Holt Renfrew Monde Redpath Museum, McGill University 7 Le Château Apartments 14 St. George’s Anglican Church 859 Sherbrooke West, Montreal, Quebec 8 Erskine and American Church 514.398.4086 www.mcgill.ca/redpath Redpath Museum McGill Faculty Club 1 859 Sherbrooke West 23450 McTavish Street Built with: Built with: Trenton limestone, a sedimentary Trenton limestone, a sedimentary rock from the Ordovician of Que- rock from Quebec, formed during bec, about 470 million years old. the Ordovician Period. The red clay bricks on the side wall are made What to look for: from black shale, another sedimen- On the west side of building, directly across the road from the glass tary rock from the late Ordovician, about 430 million years old. and metal tower, look at the stones at the base of the building, near the centre. What you see is a white shell with fi ne ribs or raised stripes. What to look for: This shell is called Rafi nesquina alternata and it belongs to a group of Walk along the driveway and look at the red bricks animals called brachiopods. on the side wall. Find the cat’s paws imprinted in the bricks. Is this a fossil? No. When these bricks What is a brachiopod? were made in the Laprairie Brickyards over 100 Brachiopods are a group of animals that years ago, the clay was left to dry in moulds rather form shells, but which are poorly known than being baked in a kiln or fired. Cats walked because there are not very many of them over the wet bricks and left their paw prints on in modern oceans. They were very com- them. mon in the ancient oceans, especially dur- ing the Paleozoic era, about 543-250 mil- CIBC Building lion years ago.The soft part of the animal is 31010 Sherbrooke Street West encased within the shell and divided into two regions by a membrane or wall. The front part Built with: of the cavity contains a coiled and hairy band called the lophophore, Anorthosite. This stele or monument is from which helps in food gathering and breathing. The mouth is in the cen- Saint Nazaire, east of Alma in the Eastern ter of the dividing wall at the base of the lophophore. The gut, stom- Townships region of Quebec. It was formed dur- ach, digestive glands, and sex organs are in the cavity behind the wall. ing the Precambrian, about 1 billion years ago. Water currents set up by the cilia or hairs on the lophophore carry small food particles toward the mouth. What is Anorthosite? digestive gland stomach and intestine Anorthosite is a very hard, igneous rock formed from molten material that cooled inside the earth. Anorthosite is rare; it is more common on the surface of the moon than the earth. Anorthosite is known as A brachiopod muscles ‘“Black Cambrian granite” and you will find it used for steps, statues shell cut in half and monuments. It is polished to bring out the colours of the differ- kidney to show the mouth ent minerals. The pink granite that you are walking on is from Finland internal structure lophophore gonad and is called Rapakivi granite. Atholston House Holt Renfrew 41172 Sherbrooke Street West 61300 Sherbrooke Street West Built with: Built from: Trenton limestone, 470 million years old. Stanstead granite on the base. The walls are made of Indiana limestone from the What to look for: Bloomington-Bedford area of Indiana. The In the stone right under the bay window limestone was formed about 360 million and on the stairway are broken pieces of years ago during the Carboniferous Period. fossils laid down in layers; this is called bedding or stratification. What to look for: What is bedding? If you look closely at the walls on the east side of the building going Most sedimentary rocks show distinct layers or strata, which is the down rue de la Montagne you will see that it is made of many broken Latin word for ‘layers’. After animals in the water died they fell to the pieces of calcite and small disks. These disks are the fossils of ancient bottom of the sea, slowly building up thick layers or strata. This accu- crinoids, or “sea lilies”, and the building stone is called encrinal or cri- mulation of shells and body coverings compressed into a solid mass noidal limestone. and formed limestone. What is a crinoid? Crinoids are animals that look like flow- Mount Royal Club ers on jointed stalks. The flower part, or 51175 Sherbrooke Street West calyx, has both a mouth and an anus and is surrounded by many feathery arms Built with: that gather food into the mouth. Species that live attached to the sea floor have Trenton limestone, a sedimentary a stalk which is actually a column made rock from Quebec, formed during the of many segmented pieces. Most beds Ordovician Period, about 470 million of crinoidal limestone consist mainly years ago of broken columns, with few calyxes. What to look for: Relatives in today’s oceans include star- On the stone wall by the sidewalk are fish, sand dollars, sea urchins and sea gastropod molds from the sea snail cucumbers. called Maclurites. Close-up of mouth crinoid calyx What is a gastropod? arms Gastropods are snails and slugs. Their coiled shell protects the snails from predators and desiccation (drying out). This snail lived about 470 million years anus ago, when this area was a tropical sea. Le Château Apartments Erskine & American Church 7 1321 Sherbrooke Street West 8 1339 Sherbrooke Street West Built from: Built from: This building is made of very distinctive Three different types of rock: The grey sedi- Tyndall limestone from the Garson Quarry mentary stone on the walls is limestone. about 40 km northeast of Winnipeg. The olive brown bands are sandstone. The steps and walkways are made of grey What to look for: granite. Look at the base of the tower and All the most exciting fossils can be found notice how the sandstone is wearing away on the eastern wall of the building on rue more quickly than the other rocks. de la Montagne. You will find gastropods (see Building 5), cephalopods and corals. Why is the sandstone wearing down? Sandstone is porous and takes more pun- What is a cephalopod? ishment than the limestone when it rains Cephalopods are the brainiest of marine mollusks. They are predators in the summer or freezes in the winter. Although limestone is a very that move around by water jets. The shell is divided internally strong rock, it reacts to acids. Acid rain eats into the limestone and into chambers or partitions; the animal occu- dissolves minerals within it. These are then absorbed by the porous (below) fossil pies only the front opening of the shell. Its cephalopod sandstone beneath as the water washes over it. head is surrounded by tentacles which usually have hooks or Musée des Beaux-Arts suckers. The most com- 9 mon living forms are the 1379 & 1380 Sherbrooke Street West squid, octopus, cuttlefish (above) Built from: prehistoric and nautilus. Both buildings are made What is coral? cephalopod with Vermont marble, The round structure, composed of many small tubes or chambers, is a a metamorphic stone. colonial coral. The animal or polyp that lives inside each chamber is a Layers and folds of grey simple bag-shaped creature with no specialized organs. A ring of ten- and black minerals run tacles at the top of the bag allows the polyp to collect food and push through this fine-grained it through the central mouth.