Rock Lobster EarthCache
junglehair: Thanks to everyone that visited this EarthCache. Time to archive.
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There is no physical container hidden at this location. Instead you will need to answer the questions at the bottom of the listing in order to log your "find". This EarthCache will highlight a rock formation known as a "mélange" at Lobster Head Cove in Gros Morne National Park. An entrance fee is required to visit this park.
People often visit Lobster Cove Head to see the lighthouse without ever knowing that below their feet lies some amazing geology exposed at the cliff edge. You will need to follow the trail down to the shoreline, then walk around to the head of the cliff. Please note that you will not be able to access this EarthCache location at high tide. Most other times, you should be able to walk around the headland. Be sure to keep well away from the cliff edges as there is always the danger of falling rocks.
The theory of plate tectonics is such a central theme in geology that it's hard to believe it was only 50 years ago in the mid 1960s when this theory gained general acceptance. The geology of Newfoundland has helped to support and advance the theory of plate techtonics. Newfoundland marks the site where one of the earth's great continental plates split apart about 600 million years ago and then collided again some 200 million years later. When this ancient continental plate split, the two smaller plates began to drift away from each other, and in the space between them an ocean was formed. This ocean has been termed the Iapetus Ocean, and it reached at least 1000 km in width before the wayward drift of the continental pieces was halted, and the two began to come together again.
As the Iapetus closed, between 500 and 450 million years ago, the eastern plate (Eurasia and Africa) slid over the North American plate. Slices of oceanic crust and mantle were thrust into stacks, which were subsequently sliced and restacked. These slices were pushed westward on top of sedimentary rocks crushing them into a mélange of limestone blocks embedded in a shaly ground-mass.
Here at Lobster Cove Head, beds of buff-coloured dolomite (magnesium-rich limestone), shale and ribbon limestones were folded and faulted as slices of ocean floor slid over them. They were originally deposited as the deep-sea portions of submarine landslides.
Logging Questions:
Please email the answers to the following questions to junglehair using the link in her profile: (visit link)
1) What are the 3 main colours you see in the cliff?
2) Do the boulders on the beach appear to be the same type of rock as you see in the cliff?
3) Try to locate a fault line within the rock. Look for matching rock layers that appear to be offset from each other. Estimate the distance of the offset.
4) What differences do you see between the rocks near the top of the cliff and the ones near the bottom?
Once you have emailed you answers, go ahead and log your find. We will respond to let you know if your answers were correct. We hope you enjoy visiting this amazing area as much as we did.
Photos are not required, as per the guidelines, but feel free to add photos to your log if you want to share your experience with others.
References:
Department of Natural Resources, Geology of the West Coast of Newfoundland
(visit link)
Parks Canada (1990) Rocks Adrift: The Geology of Gros Morne National Park. Rocky Harbour, NL. Gros Morne Co-operating Association.
Additional Hints
(No hints available.)