Barringer 3

 

Impact and Shock effects

 

The culprit 

 

 Unshocked / ordinary Sandstone  

Below the Moenkopi Sandstone and Kaibab Limestone, the Coconino / Toroweap sandstones were calmly lying.

The impact of the meteorite not only caused its vaporizing, but the blast and subsequent heat and pressure altered the structure of the material. Grains squeezed together, and eventually, the high pressure forms of quartz, Coesite and Stishovite were formed. It was the detection of these minerals by Eugene Shoemaker and Ed Chao that conclusively proved the impact formation of Meteor Crater, and set the stage for recognition of other impact craters on Earth.

Since that time, discovery of shocked quartz and/or shatter cones has clinched the determination of impact. Crater morphology and meteoritic material help a lot too!

 Moderately Shocked Sandstone

"Notably" Shocked Sandstone 

 

 Highly Shocked Sandstone

 

 

 Highly Shocked Coconino Sandstone, on unshocked Coconino Sandstone

The difference in density is amazing, the shocked sandstone is significantly less dense!

 The original layers are still visible in the shocked sample.

 

Shattercone - I was told this was a shattercone from Meteor Crater... however, other reading suggests that no shattercones have been found there. It does look similar to Steinheim shattercones...
 

 

Meanwhile - outside the crater

 

They really don't want you walking around looking for things. Truth is, people have been over this area so much, there are certainly next to no examples of meteorite shale or meteorite to find. What can be found by passing a magnet through the sand, is a lot of Magnetite (from volcanoes to the west) and occasionally Meteorite Spheroids, condensed / cooled metal from the meteorite after it vaporized/melted.
However, it you park too long on the side of the road, a Meteor Crater pickup truck will come by and tell you you can't do what you are doing and it's time to move on.

 

 Some up-ended blocks of Kaibab limestone at the craters rim

 

Looking around, the white blocky rocks are bits of the Kaibab Limestone thrown from the crater

 

 Chunk of Limestone

 

Block of Kaibab Limestone with crater rim in the distance 

 

 If you are driving old Route 66 - Now I-40, and you have a few hours, stop by and have a look. You may not think a hole in the ground is impressive, but look carefully, think about the process, try and get a feel for the real size of the crater... it's bigger than you think it is. Then imagine the size of the rock that made it - how small that is, and consider that NASA isn't even looking for something that size! [Then, when you think what this would look like on your city, write your senators and representatives and get them to allocate money for NASA to really search for NEO/PHOs]

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Page and images by ted Brattstrom - updated 15-Apr-2009