For years it was believed to be a collapsed salt dome (hence the name),
but later research, starting with Eugene Shoemaker, shows that nearly all
the evidence points to an impact origin. Recent (2008) research by
Thomas Kenkmann and Elmar Buchner have finally put the matter to
rest, finding planar
deformation features in quartz crystals embedded in the Kayenta
sandstone of Upheaval Dome's outer ring.
Here's their paper in GeoScience World:
Dome, Utah, USA: Impact origin confirmed.
(I hope someone tells the national park service; their sign at the overlook still emphasizes the salt-dome theory.)
That it is an impact crater should come as no surprise to lunar observers, since Upheaval looks remarkably like a terrestrial version of the Orientale Basin, which we see in profile on the southwestern limb of the moon, or like the Nectaris basin which is more subtle than Orientale, but has the advantage of being visible face-on from earth.
|Compare this aerial photo of Upheaval Dome:||with this face-on satellite shot of Orientale:|
For further reading, Kurt Fisher has an excellent Bibliography of Upheaval Dome references.
|Around the South Rim of Upheaval Dome|
|Upheaval Canyon and the center of the dome: a hike up into the center of the crater|
The first time we encountered Upheaval Dome, after spending a
while at the overlook staring amazed at the spectacle,
we attempted to hike the trail that winds downhill just inside the
first shock ring to the bottom, where a spur trail heads inside
the crater. Unfortunately, we
ran out of water before we got much more than halfway to the bottom.
The trail continues down toward this canyon (carved by a tributary
of the Green River) then bends around the bottom part of the outer
shock ring -- the big red rocks looming just right of center --
and the trail to the center would be just on the other side of those
Looking up from different vantage points at various parts of
the outside of part of Upheaval Dome's first shock ring.
Left, another view of the outer shock ring, and the way the terrain
beyond it drops off into the canyon; right, concentric shock rings.
Other links on Upheaval Dome, including some great aerial shots showing the double-ringed basin structure: