Buchner and Kenkmann in GEOLOGY, March 2008, report evidence of shocked quartz at Upheaval Dome vindicating Shoemaker and Herkenhoff’s description of Upheaval Dome as an impact structure in 1983. Their paper is:

Shoemaker, E.M., and Herkenhoff, K.E., 1983, Impact origin of Upheaval Dome,
Utah: Eos (Transactions, American Geophysical Union), v. 44, p. 747.


Buchner and Kenkmann's paper is:

Upheaval Dome, Utah, USA: Impact origin confirmed

ABSTRACT
Upheaval Dome is a unique circular structure on the Colorado Plateau in SE Utah, the origin of which has been controversially discussed for decades.
[...]
The shocked quartz grains were found in the periphery of the central uplift in the northeastern sector of the crater, which most likely represents the cross range crater sector.


See picture of Upheaval Dome here.

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(By the way, I hate it that so many papers in the areas of planetary science and geology are not easily avaiable to the dreaded "non-subscribers". It is like they are screaming at me: "YOU CAN'T HANDLE THE TRUTH". Good, I feel better now.)

I know you are a person who takes his physics seriously, but isn't it said that most great discoveries aren't discovered with "Eureka!" but with, "Hmmm, that's funny." Big Don