Eastern Head Cove’s Past History EarthCache
Eastern Head Cove’s Past History
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Between Bay Head and Eastern Head you will find a cove called Eastern Head Cove that exhibits a wide range of geologic history from long ago right up until today. This earthcache will help you until understand why this little cove is so important.
Welcome to Herring Cove Provincial Park, a 1,049 acres provincial park located on Campobello Island, New Brunswick near the Maine border that is best known for its trails, golf course and beautiful sand beach. Here the forces of the past and present meet to produce a beautiful little cove. Generally we look at the land and recognize that recent glacial processes coupled with weathering have shaped what we see, but this little cove is different and this earthcache will give you insight into a variety of geologic process at work across time.
Four hundred years ago, the Flemish geographer, Abraham Ortelius, knew enough about the coastlines of the Americas, Africa, and Europe, to speculate that they had once been conjoined in a single continent, and had been rent asunder by some catastrophic force. The movement, people realized, took place at the base of what we call the lithosphere. On the Earth, the lithosphere includes the crust and the uppermost mantle, which is joined to the crust across the mantle. The lithosphere is underlain by the asthenosphere, the weaker, hotter, deeper, and more plastic part of the upper mantle. The boundary between the lithosphere and the underlying asthenosphere is defined by a difference in response to stress: the lithosphere remains rigid for long periods of geologic time, whereas the asthenosphere flows much more readily. In addition, the colder rocks in the lithosphere are denser than those in the underlying asthenosphere, and thus tend to sink, given the opportunity. Thus when, for example, a section of the lithosphere is bowed down and breaks, perhaps as a result of loading by sediment eroded off a continent, the material on one side of the break may begin to sink into the asthenosphere. This process is called subduction.
The Acadian orogeny is the name of a long-lasting mountain building disturbance that most greatly affected the Northern Appalachian region (New England northeastward into the Gaspé region of Canada). The "climax" of this orogeny is dated as early in the Late Devonian, but deformation, plutonism, and metamorphism related to this orogeny continued well into the Mississippian Period. The cause of this great period of deformation is a result of the plate docking of a small continental landmass called Avalonia (named after the Avalon Peninsula of Newfoundland). The docking of Avalonia onto the margin of Laurentia resulted in the closing of a portion of the Iapetus Ocean. The Acadian Orogeny spanned a period of about 50 million years (beginning roughly 375 million years ago). During the course of the orogeny, older rocks were deformed and metamorphosed, and new faults formed and older faults were reactivated.
At this location there is evidence of this subduction in the small folds and metamorphosed rock found on the western side of the cove while on the eastern side of the cove you will see evidence of volcanic activity. The event that formed this cove took place during the Silurian and Lower Devonian period (440-390 million years). The character of the volcanic rocks of the eastern part of this cove indicates a rifting or divergence event that occurred elsewhere along a margin. Finally the glacier shaped what we currently see, which has been further finely tuned by the effects of weathering.
Remember this is an earthcache so there is no container just an earth science lesson at an amazing natural feature. To log this cache, you must post a photo of yourself or your hand with your GPS showing the view of the layers of rock in the background. Email me through my profile the size of the folds in the layer of rock just west of the posted coordinates. Please include the name of the earthcache and the number of people in your group in your email. In your log please take the time to describe what you find special about this beach.
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