craters

The New York Times reports today on some research being done using Google Earth to help identify new impact craters which may point to a higher frequency of large impacts than previously theorized. A group called the “Holocene Impact Working Group” believe there have been multiple large impacts within the last 10,000 years whereas most astronomers have believed there haven’t been any in longer than that. The new group believes there is evidence of multiple strikes which landed in the ocean. After all, the Earth’s surface is 75% water – so this isn’t surprising. The researchers have been looking for signs on land using Google Earth in the form of “chevrons” which are enormous wedge-shaped sediment deposits. Often these chevrons have fossilized ocean materials and it is believed they are formed by enormous super-tsunamis which resulted from large meteor impacts in the ocean. Already the group has identified several locations dated less than 10,000 years ago which have strong evidence of having been the result of impacts. They have also examined ocean floor data and identified the suspected impact locations themselves. They have taken soil samples from one location and found evidence of melted material only found in impact sites.
The group who has put forward the theory will be presenting at the American Geophysical Union (AGU) meeting in December. I’m planning to attend the AGU virtual globes meetings and will report if more interesting news is revealed. In the meantime, you might want to check out this collection of 172 large impact crater sites. Also, you might be interested in this story about a recently discovered crater which is easily visible in GE.

In response to the new Saharan Crater story, I was contacted by E-mail by an Editor at Sky & Telescope Magazine. He told me a reader had recently written them about a crater up on on Melville Island, on the northern part of the Sabine Peninsula. Here’s what Gerald Hanner wrote:

I have read with interest your pieces on impact craters — especially
the ones found on Earth. Some 40 years ago, when I was an Air Force
navigator, I used to fly a route from Fairbanks, Alaska, to Thule,
Greenland. At the northern tip of the Sabine Peninsula, on Melville
Island, my ground mapping radar would pick out a circular structure
with a peak in the middle; it sure looked like a crater to me,
although I never actually got a visual on it.

He goes on to say he recently checked for it in Google Earth, and there he found it very easily in this GE satellite photo . He wasn’t sure whether this was an impact crater. Based on what I’ve been learning, I think it is an impact crater. It quite clearly has two rings which is evidence of a strong impact. The main crater is about 7.5 km wide, the secondary crater is almost 14 km wide! One expert confirmed it wasn’t in a database of impact craters (I checked out this GE database of known craters as well), but didn’t have enough data to confirm. Can any other experts comment?
Thanks to Stuart Goldman, Associate Editor for Sky Publishing, for bringing this to my attention.
[EDIT 12:20 EST: Looking nearby, there appears to be an oval-shaped crater just to the northeast of this new crater. Also, there are other possible craters to the south and southeast. Very interesting!]

At a site in the Saharan desert on the border between Egypt and Libya, scientists have determined a huge 19 mile-wide crater was formed by an impact of a rock from space. More like an entire asteroid probably. They used satellite photos to help make the determination. Provided was a picture from an enhanced Landsat satellite photo. Naturally I had to go into Google Earth to see if I could find it. Not only did I find it easily, but it was quite recognizeable in GE that its a meteor crater . I’m surprised it took this long for someone to notice! The scientists said this crater is so large it probably would not be noticed except from space. Here’s the story at space.com.
You can check out lots of craters in Google Earth, and here’s a link to an earlier story I did about the crater collection.