Travel Reference
In-Depth Information
Entrance Road along Soda Butte Creek
[GEO.5]
and the East Entrance Road near Sylvan Pass
[GEO.6]
both pass through fine examples of these volcanic mountains.
he Yellowstone Caldera
The Yellowstone Caldera is the most recent of a long line of calderas that started forming
around 14 million years ago far to the southwest in what is now the southwest corner of Idaho.
A series of ever younger calderas are located to the northeast along the edges of the Snake
River Plain.
A
caldera
is the collapse of a large land area after the emptying of a magma chamber in a
massive volcanic explosion. Figure 6 shows the Yellowstone Caldera in particular, but similar
events occur in the formation of all calderas. (A caldera is not exactly the same as a volcan-
ic crater, which is a depression in the ground, usually circular in form, from which magma
erupts.) The conditions for caldera formation require the concentration of heat and magma in
a relatively small area near the surface.
Figure 6. Cross sections showing evolution of the Yellowstone Caldera event cycle.
