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***THIS CACHE IS NOW OWNED AND MAINTAINED BY GEOTEAM13646***
Drive to Scenic View Park, walk through the Pavallion, to the highest point of the rock formation, the base of the monument. Go left down the walk to the foot bridge, there is a low spot in the sea wall to take the elevation of the water level.
FRONTENAC ARCH
The plate tectonics history of New York is underlain by the “basement” of Precambrian rocks that is physically continuous with rocks in the Canadian Shield, but mostly buried under younger stratified rocks. The shield is a vast terrane of crystalline igneous and metamorphic rocks that forms the nucleus of North America and is exposed in about two-thirds of Canada. The youngest part of the Canadian Shield, called the Grenville Province, lies along the eastern edge of Canada. It occupies a northeast-trending strip of several hundred miles wide extending for nearly 1300 miles from Lakes Huron and Ontario to the northeast coast of Labrador. New York’s exposed crystalline basement rocks are an extension of this Grenville Province; they include the Adirondacks, Thousand Islands, Hudson Highlands, and the Fordham gneiss, all of which range in age from 1300-1100 millions years. The Canadian Shield is ancient Precambrian bedrock and the Adirondack connection with the Grenville Province of the Shield is the Frontenac Arch, exposed in the Thousand islands.
By middle Cambrian time the “Potsdam Sea” had invaded the region southeast of the Adirondacks, and by the late Cambrian time it began to advance westward along the northern edge of the mountains. The North Country, with the Adirondacks proper remaining above sea level to form a peninsula connected to the Canadian Shield by the narrow Frontenac Axis.
The geologic configuration similar to the approach to the Adirondack Dome from the St. Lawrence River you are “climbing up” onto another uplifted feature called the Frontenac Arch. The Arch tends northwest ward through Alexandria Bay. Its uplift appears to be contemporaneous with doming of the Adirondacks, and the apparently once continuous blanket of Potsdam and Theresa strata has been similarly removed by erosion on the crust of the uplifted. The dip of these beds away from the Arch is almost imperceptible in single road cuts. But it is indisputable.
The Thousand Islands are the surface expression of the Frontenac Arch, and the visible connection between the Grenville Province of the vast Canadian Shield and the Adirondacks. The gneisses of the island and Alexandria Bay are mostly pink, massive rocks of granite composition, called Alexandria Bay gneiss, or Thousand Islands gneiss, but darker, syenitic and banded gneisses also occur.
The Islands themselves are elongated parallel to the river and display similar rounded form with pronounce asymmetry of cliffy, upstream ends and gentle, downstream trailing slopes. This indicates that glacial advance during the Ice Age was up valley toward the southwest, more or less parallel to the river. These features may be viewed t close range by crossing the Thousand Island Bridge on Interstate 81 south west of Alexandria Bay to Wellesley Island State Park.
Between Exit 48 and the Thousand Islands Bridge south of the Alexandria Bay, the road traverses nearly level land developed over the first Black River limestone, then Theresa formation and finally Potsdam sandstone, not far from the contact between the latter formation of the underlying Precambrian gneisses, marble, and schist of the Lowland Adirondacks, The lower Paleozoic beds here dip slight to the southwest as a result of the geological young rise of the Frontenac Arch. The Arch tends northwestward across the St. Lawrence Rive and responsible for the erosion stripping of Therese and Potsdam beds and exposure of the underlying Precambrian terrane in the Thousand Island region.
From the traffic light on Route 12, continue down Church Street, turn left at the hospital and proceed to the Scenic Park. You are now situate on the crest of the Frontenac Axis, a ridge of resistant Grenville rocks which connects the Adirondacks with the ancient core of the continent, the vast Precambrian terrane of the Canadian Shield. The Frontenac Axis forms the Thousand Islands where it is crossed by the postglacial St. Lawrence River. This is just a few miles from where the river spills out of Lake
Many of the Grenville rocks had their beginning as sand,lime mud, and clay deposited in seas adjacent to the continent. This Pre-Grenville period spanned perhaps hundreds of millions of years, when continental and oceanic crust were locked together. The coastline then must have been a painfully desolate place: flat, devoid of land plants or animals, and nearly lifeless sea except for mounds of blue-green algae, or stromatolites, poking their cabbage-like heads above the tidal flats.
The ocean basin began to close. Volcanic eruptions added their material to the sedimentary pile. By about 1300 million years ago the oceanic crust bordering the early continent was completley consumed, and the continents slowly collided, creating a lofty mountain range strectching from Labrador to Mexico that we'll call the ancestrial Adirondacks. Rocks formed on the margins of both the continents that borderd the closing ocean and crumled, metamorphosed, and partly melted at great depth.To log earthcache you must post a picture of you with your GPS take in the park with the River in the background and email me the answers to the following:
1. Name the Island connected to The Scenic View Park,
2. Name the Island Bold Castle is on,
3. Can you see Canada from Scenic View Park,
4. What is the elevation at the highest point
What is the elevation at the waters edge.
Additional Hints
(Decrypt)
Fgnaq ng gur onfr bs gur zbahzrag, snpr 30 qrterrf, ybbx whfg nobir Obhl T 189, orgjrra Fgrnzobng Vfynaq naq Qrre Vfynaq.