The Matterhorn in Toronto
In front of you, if you look up, look way up, standing above you is a massive structure, Toronto’s CN Tower, one of Canada’s iconic images. But, if you look down, right in front of you, you will see just a small fragment of something much greater than the CN tower, a chunk of gneiss from Switzerland's Iconic Matterhorn. A mountain that is so symbolic, “Swissness” legislation introduced in 2017 restricts the use of its image to products fully produced in Switzerland, as we learned when the Swiss Chocolate Bar 'Toblerone’ production was moved out of Switzerland.
Now, let's do a comparison. The CN Tower, that Massive structure in front of you stands at a whopping 1,815 feet (553 meters). By comparison, that hunk of Gneiss comes from the Iconic Matterhorn that stands at 4,477.54 m (14,690 ft).
What's that, you're not good at math, let me take care of that for you. The Matterhorn is about 8 times higher than the CN Tower. Take a walk back towards Bremner Blvd, and look up, way up past the top of the CN tower, and imagine the massive height of Switzerland Iconic mountain.
Here is a bit of Geological history to help us understand this Mountain, courtesy of geologyscience.com .
Formation: The Matterhorn, part of the Swiss Alps, were formed as a result of the collision between the African and Eurasian tectonic plates. (More about this later)
Rock Composition: The Matterhorn is primarily composed of rocks such as gneiss and granodiorite (metamorphic rocks) formed under high pressure and temperature conditions.
Glacial Erosion: The Matterhorn’s distinctive shape was sculpted by periods of glaciation, ice flows and glaciers that carved out valleys and shaped the mountain’s features, including its iconic faces.
Now, since this is an EarthCache, and not a Virtual Cache, let's take a closer look at the rock sample itself:
What Is Gneiss?
Gneiss is a foliated metamorphic rock identified by its bands of varying mineral composition. Some of these bands (or lenses) contain granular minerals that are bound together in an interlocking texture. Other bands contain platy or elongated minerals that show a preferred orientation that parallels the overall banding in the rock. It is this banded appearance and texture - rather than composition - that define a gneiss.
How Does Gneiss Form?
Gneiss usually forms by regional metamorphism at convergent plate boundaries (When continental and oceanic plates collide, the thinner and more dense oceanic plate is overridden by the thicker and less dense continental plate).
The most common path begins with: Shale (sedimentary rock); then morph through, slate, then phyllite, schist, and then finally into gneiss. During this transformation, clay particles in shale transform into micas and increase in size. Finally, the platy micas begin to recrystallize into granular minerals. The appearance of granular minerals is what marks the transition into gneiss.
Although gneiss is not defined by its composition, most specimens have bands of feldspar and quartz in an interlocking texture. These bands are usually light in color and alternate with bands of darker-colored minerals.
Questions to be sent to the CO:
1) Which way are the planes in the Gneiss specimen here in relation to the ground? In other words, if you think about this rock sample as an assembly of flat plates, would they be parallel to the ground, or standing on their ends.
2) Determine the volume of this rock sample? Length x Width x Height = cubic dimension with a density of 179 lbs / cubic foot or 2,867 kg / cubic metre.
3) This rock sample is primarily one colour, but there are a number of large patches of a contrasting colour, what is it?
4) What's taller? The Matterhorn or the CN Tower, by how much?
5) According to the sign at GZ, what month and year was this rock sample presented.
6) Finally, post a photo giving this rock sample the thumbs up - if possible include the CN Tower in the background.
References: Geology.com; geologyscience.com