Geology of the United States A slice of the Earth from the Pacific Ocean through the Pacific Northwest might look something like the adjacent image. Beneath the Cascades, a dense oceanic plate plunges beneath the North American Plate; a process known as subduction. As the oceanic slab sinks deep into the Earth's interior beneath the continental plate, high temperatures and pressures allow water molecules locked in the minerals of solid rock to escape. The water vapor rises into the pliable mantle above the subducting plate, causing some of the mantle to melt. This newly formed magma rises toward the Earth's surface to erupt, forming a
Thermal history of the Earth heat flow from the core mantle boundary. formula_10 is the secular cooling heat from the core, and formula_11 and formula_12 are the latent and gravitational heat flow from the inner core boundary due to the solidification of iron. Solving for formula_13 and formula_14 gives, and, In 1862, Lord Kelvin calculated the age of the Earth by assuming that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface to cool to its present temperature. Since uniformitarianism required a much older Earth, there was a contradiction. Eventually, the additional heat sources