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The Ginkgo basalt was examined over its 500 km (310 mi) flow path from a Ginkgo flow feeder dike near Kahlotus, Washington to the flow terminus in the Pacific Ocean at Yaquina Head, Oregon.
The basalt had an upper melting temperature of 1095 ± 5 °C and a lower temperature to 1085 ± 5 °C; this indicates that the maximum temperature drop along the Ginkgo flow was 20 °C.
In the middle Miocene, 17 to 15 Ma, the Columbia Plateau and the Oregon Basin and Range of the Pacific Northwest were flooded with lava flows.
Both flows are similar in both composition and age, and have been attributed to a common source, the Yellowstone hotspot.
The Latah Formation sediments of Washington and Idaho are interbedded with a number of the Columbia River Basalt Group flows, and outcrop across the region.
Absolute dates, subject to a statistical uncertainty, are determined through radiometric dating using isotope ratios such as (800,000 sq mi) in Russia.
The lava must have spread quickly to achieve this uniformity.
Analyses indicate that the flow must remain laminar, as turbulent flow would cool more quickly.
The Yellowstone hot spot volcanism track shows a large apparent bow in the hot-spot track that does not correspond to changes in plate motion if the northern CRBG floods are considered.The ultimate cause of the volcanism is still up for debate, but the most widely accepted idea is that the mantle plume or upwelling (similar to that associated with present-day Hawaii) initiated the widespread and voluminous basaltic volcanism about 17 million years ago.As hot mantle plume materials rise and reach lower pressures, the hot materials melt and interact with the materials in the upper mantle, creating magma.This could be accomplished by sheet flow, which can travel at velocities of 1 to 8 metres per second (2.2 to 17.9 mph) without turbulence and minimal cooling, suggesting that the Ginkgo flow occurred in less than a week.The cooling/hydraulics analyses are supported by an independent indicator; if longer periods were required, external water from temporarily dammed rivers would intrude, resulting in both more dramatic cooling rates and increased volumes of pillow lava.