Please be aware that Gros Morne is a fee area. Also, please DO NOT collect rocks or fossils from this site, since it is a National Park.
Logging Requirements:
- At GZ find a piece of each: (red) oxidized peridotite, (black to dark green) unoxidized periodite, (green to gray with a snake skin surface) serpentinite. What are THREE things that are differences between the three other than color? DO NOT COLLECT—THIS IS A NATIONAL PARK!
- Do you see more serpentinite near or far from water/creeks/seeps/streams? Why? (see description, audio tour, common sense)
- TAKE ALONG A DARK COTTON PIECE OF CLOTH/CLOTHING you don’t care about. Dip it in water coming from a SEEP near GZ (NOT the main creek esp at flood stage). Is there a bleaching action that takes place? Explain geological reason. YOU CAN EASILY DO THIS FROM THE BOARDWALK! OR
- dip your fingers in the water, then rub them together. Describe the sensation. Does the water/wetness feel chalky, soapy, gritty, pure?
Geology:
The view of barren red/black/gray in front of you is the uppermost layer in the Humber Arm allochthon is a slab of the earth’s mantle that use to lie sever miles/ km below the surface. This piece of the mantle used to lie at the bottom of the ancient Iapetus ocean. Thanks to glacial action during the last Ice age, the layers of rock that usually exist above the mantle were scraped away leaving one of the most pristine examples of exposed earth mantle in the world.
Geologically, the altered peridotite before you has been changed in two ways. This rock was intended to be far underground, and is thus unstable in the cold damp climate of Newfoundland. Add to that the water seeping and running down the creeks and streams across the Tablelands, and you have water helping to turn the peridotite into serpentinite. This process also changes the water chemistry, making it a ph of 12 on a scale of 0-14. (Note: household bleach is ph 10). See logging requirement #3.On the surface the process of alteration is oxidation (rusting) that makes the peridotite look like Mars.
Both the American and Canadian space agencies have declared the Tablelands to be a Mars analog, meaning that peridotite and serpentinite are rocks that have been identified as existing on Mars.
Geological Terms:
Analog – geologically similar to another environment, in this case the planet Mars
Peridotite -- is a dense, coarse-grained igneous rock, consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. …. Peridotite is derived from the Earth's mantle, either as solid blocks and fragments, or as crystals accumulated from magmas that formed in the mantle” (Wikipedia “Peridotite”)
Serpentinite – is formed from ultramafic rocks such as Peridotite when it is metamorphized by heat and water. Serpentinite has a lot of olivine in it since Olivine is altered in the chemical process and forms the greenish hue within the Serpentinite.
Oxidation – rocks containing iron rust when they are exposed to air. This “rusting” process is a visible form of oxidation.
Alkaline/basic Ph – high ph water limits the aquatic life that can live in these pools. Microbes that do survive are called extremophiles.
Resources:
Hild, Martha Hickman., and Stephanie Porter. Geology of Newfoundland: Touring through Time at 48 Scenic Sites. Portugal Cove-St. Philip's, N.L.: Boulder Publications, 2012. Print
"Serpentinite." Wikipedia. Wikimedia Foundation, 06 Apr. 2013. Web. 15 July 2013.
"Peridotite." Wikipedia. Wikimedia Foundation, 06 Apr. 2013. Web. 15 July 2013.