Travel Reference
In-Depth Information
Figure 5. What's under Yellowstone: Moving plates, mantle plumes, and the Yellowstone hot spot.
The cross sections in Figure 5 are approximately southwest to northeast, from the coast of
northern California to just east of Yellowstone Park, and reflect current geoscientists' think-
ing about what is now under the park.
A
shows the formation of the Absaroka Range about
45 million years ago. The oceanic plate is subducting in a northeastern direction under the
overriding North American Plate. It has reached deep enough for melting to start and to form
the
magmas
that rose and created the Absaroka volcanoes 53 to 44 million years ago. Most
subducting plates dive into the earth at a very steep angle. It is one of the curious things about
western geology that this oceanic plate went down at a very shallow, almost flat, angle.
B
il-
