The Frontenac Axis EarthCache
Remote Sensor: Moving on.
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This cache is designed to done by car as you drive by. Heading along Highway 10 you pass through the unique divide between two significantly different geologic features. The highway department has done some widening so the features are very exposed.
Welcome to the Frontenac Axis! This is a narrow extension of the Canadian Shield which traverses the area and links the Algonquin Highlands with the Adirondack Mountains. At the posted coordinates you are straddling the join between the St. Lawrence Lowlands and the Shield.
St. Lawrence Lowlands
The sedimentary rocks that lie under the surface of the Great Lakes and St. Lawrence Lowlands were formed some 500 million years ago, in the early Paleozoic Era. At that time, a shallow sea existed along the southern edge of the Canadian Shield. Over time the water and the sediments at the bottom of the sea pushed down on sediments beneath them. This pressure gradually turned the lower sediments into sedimentary rocks such as limestone.
Canadian Shield
The Canadian Shield, also known as the Precambrian Shield or Laurentian Plateau, covers about half of Canada as well as most of Greenland and part of the northern United States; an area of 4.4 million square kilometers (1.7 million square miles).
It is the oldest part of the North American crustal plate and contains fossils of bacteria and algae over 2 billion years old.
The shield is composed of granite and the earth's greatest area of exposed Precambrian rock (igneous and metamorphic rock formed in the Precambrian geological era 500 million years ago).
The shield was the first part of the continent to be permanently raised above sea-level. Subsequent rising and falling, folding, erosion and continental ice sheets have created its present topography. The reoccurring invasion and withdrawal of the ice sheets (1.6 million to 10,000 years ago) depressed the surface creating Hudson Bay, scraped out tens of thousands of lake basins, carried away much of the soil cover and redeposited glacial debris.
The shield plateau ranges from 305 to 610 meters (1000 to 2000 feet) above sea level. In northern Labrador and Baffin Island the crustal plate has tilted so much that it rises over 1,500 meters (5,000 feet) above sea level. There are a number of mountain ranges within the shield: the Adirondack (northeastern New York state), Superior Highlands (northern Minnesota, Wisconsin & Michigan states), Torngat and Laurentian.
The shield is a rich source of metallic minerals such as iron, nickel, copper, zinc, uranium, gold, silver, platinum and molybdenum.
Your tasks at the cache location are straight forward, but may require you to do a little research after the drive:
If you look North from the coordinates you will see an exposed outcrop of the Shield, two Pre-Cambrian rock types are visible, what are they?
Looking South is the exposed St. Lawrence Lowlands, what is the rock type here?
Email me the answers.
Both answers can be derived by visually checking as you drive-by.
Time warp from billion year old rock to 570 million year old in a couple of metres.
Additional Hints
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Treasures
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