Santa Fe Impact Structure

December 2011

"The Santa Fe impact structure is an eroded remnant of a bolide impact crater in the Sangre de Cristo Mountains northeast of Santa Fe, New Mexico. The discovery was made in 2005 by a geologist who noticed shatter cones in the rocks in a decades-old road cut on New Mexico State Highway 475 between Santa Fe and Hyde Memorial State Park. Shatter cones are a definitive indicator that the rocks had been exposed to a shock of pressures only possible in a meteor impact or a nuclear explosion. It is called an "impact structure" and not a crater because it is so deeply eroded. Current estimates place the age of the impact between 1.4 and 1.6 billion years. Only the crater's basement rocks remain on the surface in the mountains today. The estimated diameter of the structure is currently a subject of study, but may be 10 times larger than the one that created Meteor Crater in Arizona. The shatter cones occur for about 1 mile (1.6km) along the highway, which is interpreted to coincide with a central area within a crater of greater diameter. " From wikipedia

Since it turned out I was going to Santa Fe (and other places) over the winter break, I figured, what better time to look for shatter cones when they are likely buried beneath the snow!!!

Part 1 - How do you get from downtown to Highway 475?

A map

After that, where???

Keep going out the Hyde Park Road / Highway 475 - Trees, roadcuts, hiking trails.... when you get to the visitor center or ski rental shop, you've gone too far! turn around and go back towards Santa Fe - Pull off at the pull-out on the left side where the nice exposure is... Carefully cross the road... The closer you get, the more you see... 

In Earth View

Here's our site of interest -
The nice exposure - at least it was mostly snow free

And the following is what is interesting about it:


Earth Impact Database Page  It doesn't say much - an estimated diameter of 6-13 km, and an age <1200 Million years ago.

Fackelman, S.P.; T. H. McElvain, J. R. Morrow, and C. Koeberl (2007). "Shatter Cone Exposures Indicate a New Bolide Impact Structure near Santa Fe, New Mexico". Lunar and Planetary Science XXXVIII. Lunar and Planetary Institute.

Tegtmeier, E. L.; H. E. Newsom, W. E. Elston, and T. H. McElvain (2008). "Breccias and geological setting of the Santa Fe, New Mexico USA impact structure". Large Meteorite Impacts and Planetary Evolution IV. Lunar and Planetary Institute.

Map images courtesy Google, all other images Copyright Ted Brattstrom 2011, 2012
webpage by ted Brattstrom - Update 14 Oct 2012