Where can we see meteorite craters in North America?

Got a geology question for Doctor Rock? Send it in!

Dear Dave,
This winter an asteroid missed the Earth by a fairly close margin, and a meteorite swooshed across the sky in Siberia, leaving some fragments but no crater. Those events got the family all excited. We have decided that we would like to visit meteorite craters when we take our family vacation this summer. We have heard of the Meteor Crater in northern Arizona. Are there others in the US or Canada to put on our list?
Jeannette Blankenship, Sioux Falls, South Dakota

Dear Jeannette,

Artist's depiction of a very large meteorite strike. NASA

Great topic. There are many other meteorite craters. But, most are very old and deeply eroded, so they are not very obvious form the ground, or even from the air. Many have been detected using gravity studies (that's a whole different topic!). Meteorite craters are called 'astroblemes'- an obscure but logical term when you think about it for a couple of minutes. To be sure we are all using the correct terms, a 'meteor' becomes a 'meteorite' when it impacts the earth. Not all meteorites come from the asteroids, some are known from Mars and the Moon.

The Barringer Crater in northern Arizona. For scale note the road snaking in at upper right. This photos is from NASA.

'Meteor Crater' (known to science as the 'Barringer Crater' after the discoverer) in northern Arizona is the best known, and the most accessible for your family. The crater is 3/4 mile across and 575 feet deep. It was formed 49,000 years ago when a nickel-iron meteorite weighing around 300,000 tons and 150 feet across hit the earth at a velocity of 28,600 mph. (You may find higher velocities cited on the internet, but this one is from the latest published scientific calculations).

Probably the next best from a spectator's perspective in North America is Upheaval Dome (this link gets you to some great photos) in Canyonlands National Park, near Moab, Utah. This circular structure does not look like a crater. The layered rocks that make up the local bedrock are deformed into a circular structure 1.7 miles across. For years, many geologists thought it could be caused by a dome of salt rising upward and displacing the strata,21 but recent geologic study shows that it is almost certainly the result of an impact around 170 million years ago.

There are others, but they are pretty obscure. Find a map of North American impact craters at the website of the Planetary and Space Science Centre, University of New Brunswick. If you use Google Earth, the PaSSC. An impact site map at Geology.com let's you learn more about 50 of these impact sites around the world. And this website has a .kml file you can download into Google Earth that shows the location in great detail of known and suspected craters all over the world.

So, have a great summer trip, Jeannette!

Dr. Rock

Dino Bones in New England

Dear Doc Rock,
     My family had a great road trip to the western US last summer. The kids (7 and 10) became rabid dinosaur nuts after seeing fossils at Dinosaur National Monument in northwestern Colorado. What a fabulous place to visit. Fossil bones were being excavated right in the visitor center.
     Did dinosaurs only live in the western part of North America. Is their anyplace close to our home in New England to see dinosaur fossils?

Jake Orr
Pittsfield, Massachusetts

Dear Jake,
     I became a dino-nut at about the age of your youngest. I still have a couple of books from that era of my life, which I'll admit was not all that long after the poor brutes went extinct. I'm pretty sure it was my early interest in dinosaurs that led me to become a geologist, and look where that got me! Now I'm on the internet and I have a blog. Great things await your dino-nuts!
     Dinosaur fossils are known from across North America, as long as the rocks are 1] of the right age, 2] exposed through erosion, and 3] those rocks have not been metamorphosed or too badly destroyed by faulting or intrusions. The western USA and Canada have the best combination of rocks and conditions to preserve dinosaur fossils. This website from the Washington State Department of Natural Resources lists some place to see dino fossils in the wild. It is sort of ironic, since no dinosaur fossils have (yet) been found in Washington.

Dinosaur tracks at Dinosaur State Park, Connecticut. Photo by Ken Zirkel (LeKriz). More  photos on Flickr

     Hmmmm, dinosaurs in New England. Massachusetts and Connecticut are famous for preserved dinosaurs foot prints. Dinosaur Footprints Reservation just north of Holyoke, Massachusetts is a famous dinosaur footprint site. There are hundreds of tracks preserved on sandstone slabs. They were left by a probable carnivorous dinosaur about 15' long of an unknown species- no fossil bones have been found with the tracks to identify the animal. The foot prints were given the scientific name Eubrontes giganteus. They were found in 1802, and are the first North American dinosaur fossils described by scientists. That alone makes the Heritage Reservation important. Visit their website for directions and information.

Eubrontes fossil dinosaur tracks at Amherst College.

    Dinosaur State Park in Rocky Hill, Connecticut also displays trackways. Kids can make plaster casts of these tracks to take home. Check out the Park's website. Learn about the track casting at another Connecticut State Park website.
     The Beneski Museum of Natural History at Amherst College has a wonderful exhibit of extinct animal fossils, and the original dino tracks salvaged from the Connecticut valley. (I've been there, very cool for kids.)