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Comment: 02:04 - 03:09 (01:05)
Source: Annenberg/CPB Resources - Earth Revealed - 14. Intrusive Igneous Rocks
Keywords: volcano, "James Hutton", "Abraham Vernor", granite, Scotland, "igneous rock", eruption, volcano, magma
Our transcription: The study of igneous rocks began in the 1780s when Scotsman James Hutton became embroiled in a controversy with another influential geologist, Abraham Vernor.
Vernor believed that the Earth was once covered entirely by a great ocean from which all rocks formed starting with granite.
Hutton disagreed. In exploring the highlands of Scotland, Hutton observed veins of granitic rock slicing across sedimentary strata.
He reasoned that the granite must have been injected into the strata as a molten liquid and not been precipitated from a primordial sea.
He made a link between granites formed at depth and the quickly cooling deposits of erupting volcanoes.
Both are products of molten liquid or magma from Earth's interior.
Thanks to Hutton, geologists recognized a new class of rocks called "igneous", literally fire formed rocks.
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