Rocks formed all over the world can be found in our McMaster gardens, pathways, and architecture.By observing different features of a rock, one can learn a lot about the environment in which it was deposited in. Geologists use these features as clues to help recontruct past environments, and to predict where important resources are!
From the Faculty of Science graduating class of 2006, three gneiss rocks (pronounced ‘nice’) were given to McMaster, and were placed in front of the Life Science building.
Gneiss, a high grade metamorphic rock, is composed of the same minerals found in granite. Gneiss is recognizable by its distinct banding pattern (foliation) of light and dark minerals, created through exposure to intense heat and pressure.
Benches made of packestone at Divinity College make for a quiet retreat for students to study and get some fresh air!
Packestone is grain supported carbonate rock. This means that there are more fossils and large clast fragments in the rock compared to the clay, or matrix, content holding the fragments together.
Several large decorative gneiss (pronounced ‘nice’) rocks found in the Arts Courtyard next to KTH and the Michael G. DeGroote Building.
Gneiss is a high grade metamorphic rock, meaning it is formed when a pre-existing rock like sandstone, shale, or granite, undergoes conditions of extreme high temperature and pressure. Shale that is metamorphosed will become slate, phyllite, and schist, before it becomes gneiss.
Dolostone blocks make excellent benches outside the front entrance of MDCL.
Dolostone is a sedimentary rock composed mostly of the minerals calcium, magnesium, carbon, and oxygen. Dolostone is formed from limestone via a process known as diagenesis, when magnesium in pore water is substituted for some of the calcium in the original limestone. As the magnesium takes up less physical space than calcium in the rock, void spaces called vugs form. Vugs are small cavities within the rock and give dolostone its characteristic appearance.
Mudstone: MDCL Atrium
The MDCL Atrium waterfall is lined with bricks made of laminated mudstone rocks.
The mudstone bricks are sedimentary rocks, laminated with alternating layers of fine grained clay particles (darker colour) and slightly courser grained silt particles (lighter colour). The clays were deposited in an extremely calm environment and the silts were deposited in an environment with slightly more enery present.
A granite rock memorial to Gwen George, wife of McMaster President Peter George, sits in the Gwen George Memorial Garden in front of BSB.
Granite is an igneous rock formed from magma cooling and crystallizing within the earth at depths up to 50km within the earth’s crust. Most granite was formed during the Precambrian era, which began 4500 million years ago and ended 542 million years ago.
The old exterior wall of Gilmour Hall exposed in the MUSC is composed of sandstone bricks that show an array of sedimentary structures such as planar (flat) laminations, cross-bedding, and ripples.
Sandstone is a sedimentary rock formed from the lithification of sand grains. Structures visible within a sedimentary rock provide geoscientists with clues to interpret the depositional environment of the rock, which may include the energy available during the time of deposition, the direction of the water current, etc.
The Oasis Garden beside Faculty Hollow is home to large decrotive granitic rocks. The Science rock pictured is a granite (an intrusive igneous rock), containing large crystals, or phenocrysts, of micas, quartz, and feldspars and formed within the earth's crust.
Igneous rocks form when magma from within the earth cools and becomes a solid. Magma extruded as lava on the earth's surface will cool relatively quickly, not allowing for largel crystals to form, creating an extrusive igneous rock. Magma that is never extruded and cools within the earth's crust will cool relatively slowly, allowing for large crystals to form, creating an intrusive igneous rock.
Pillars of diorite mark the front entrance of the General Science Building on campus.
Diorite is an intrusive igneous rock, meaning that it formed as magma that cooled under the ground. The magma is generated most often at volcanic arcs or mountain building regions. The main minerals in diorite are plagioclase, hornblende, and pyroxene and the light and dark speckley texture is often referred to as “salt and pepper”.
Limestone lines the walls of the General Science Building. Look closely and you can see that there are many fossils in the rock, including lots of pieces of broken up crinoids.
Crinoids, often called sea lilies, are related to starfishes, sea urchins, sea cucumbers, and brittle stars. Crinoids have lived in the world's oceans since at least the beginning of the Ordovician Period, roughly 490 million years ago.