Different Types of Rocks
There are three classifications of rocks:
- Igneous
- Metamorphic
- Sedimentary
Mostly what you witness in the Rockies are metamorphic and sedimentary rocks.
Igneous
Igneous rocks put simply are cooled molten rock. Magma is molten rock beneath the Earth's surface and due to the magma's slow cooling, intrusive igneous rocks form and are characterized by large crystals due to extended cooling time. An example of an intrusive rock is granite. Extrusive igneous rocks form when lava on the Earth's surface cools rapidly and small or no crystals form. Examples of extrusive rocks are basalt or obsidian.
Igneous rocks are rare in Alberta and are only really found near Waterton National Park or in the far northeast of the province. Chunks of igneous rocks can also be carried long distances by glaciers and be deposited in locations where there are no other examples of igneous rock around (Mussieux and Nelson, 1998).
Sedimentary
There are three classifications of sedimentary rocks and 90% of Alberta's bedrock is of the sedimentary class (Mussieux and Nelson, 1998). Sedimentary rocks are fragments (or clasts) of other rocks compressed under pressure to form a new mix of rock such as sandstone, shale, or conglomerate. Sedimentary rocks can also be chemical in nature, where saline solution evaporates to leave salt behind as halite or the skeletons of tiny marine animals are compressed to form into limestone (Mussieux and Nelson, 1998). The third type of sedimentary rock is of the organic class and coal falls under this classification. Examples include soft coal and Anthracite (hard coal).
Metamorphic
Metamorphic rocks can be considered a hybrid of igneous and sedimentary rocks. They are generally existing rocks that are compressed under immense heat and pressure to be partially melted but also have their chemical composition changed slightly. Due to the high level of compression and partial melting, these rocks are very hard and tough. These rocks are found in the southern rocky mountains of Alberta, around Jasper, and in the northeast of the province in the Canadian Shield. Examples of these rocks are Gneiss and Quartzite (Mussieux and Nelson, 1998).
What am I seeing here?
The cliff before you looks significantly different from any other location in the Rockies. Why is this?
This surface is unique in that it is alive and formed from a massive colony of microscopic plants, called Travertine Algae working together to build this cliff face. Unlike normal plants that extract carbon dioxide from the ambient air, Travertine Algae extracts carbon dioxide from the water flowing over the surface (Parks Canada, 2014).
The cliff face is made out of limestone and is constantly being created by these tiny plants (Parks Canada, 2014). Spring water seeping from the ground surface at the top of the cliff is full of dissolved limestone and as the water runs down the cliff's face, the algae extracts the CO2 therefore precipitating the limestone out of solution (Senese, 2010).
As long as the cliff's face remains moist, the limestone cliff face will continue to be constructed outward.
The Johnston Canyon Upper Falls in August
Questions
Please send me the answers to the following questions through my geocaching.com profile. You do not have to wait for an answer from me before logging but I do expect answers within a reasonable amount of time. Logs without an accompanying e-mail will be deleted.
1.) Which of the three types of rock is this cliff face?
2.) What is a major use of limestone in today's society?
3.) What action(s) (human or natural) would halt the growth of this cliff face?
References
Mussieux, R., & Nelson, M. (1998). A Traveller's Guide to Geological Wonders in Alberta. Edmonton, AB: Federation of Alberta Naturalists, and Canadian Society of Petroleum Geologists.
Senese, F. (2010). What is the Reaction of Limestone with Water? Retrieved from http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/limestone-and-water-reaction.shtml. General Chemistry Online! (2014, November). Retrieved from http://antoine.frostburg.edu.
This Wall's Alive [Sign]. (Retrieved August, 2014). Lake Louise, AB: Parks Canada-Parcs Canada
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