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Stark's Knob
Stark's Knob is a basaltic pillow lava formation near Schuylerville, New York, United States. It formed about 460 to 440 million years ago in relatively shallow sea water. It is often mistakenly referred to as a volcano, probably because early investigators described it as a volcano or volcanic plug. It was here during the Saratoga Campaign of the American Revolution that General John Stark of New Hampshire cut off the retreat of British General John Burgoyne's army, hence its name. Geology Stark's Knob formed in the Connecticut River Valley during the Taconic orogeny, when the shrinking Iapetus Ocean caused marine sediments to accrete onto the coast of the North American continent. This bulldozing effect also inevitably dragged in an island chain that probably resembled the Japanese Island chain. As a result, pressure in the rocks caused magma to erupt on the sea floor. The pillow lava that eventually formed Stark's Knob flowed out of these cracks and onto the sea floor. Fossils o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
