It has been over a month since I’ve released the first ‘impact structures’ network link for Google Earth, showing you the top 25 largest impact craters on earth. And it has been quite succesfull. (It’s in the top 3 most requested items off ThinkLemon.com)
So, after the release of ‘impact structures by continent‘ it’s now time for a fresh new release: impact structures by age. One for the most recent and one for the oldest…
The most recent impact structures
Pieces of ‘rock’ hit our planets atmosphere on a daily basis. But they’re generally the size of anything between a grain of sand up to a tennis ball. Because of friction and subsequent loss of mass they generally do not make it to the surface, let alone make a dent in the soil. To make an impact you need a decent size piece of ‘rock’ staying somewhat intact untill impact with the ground, and then hopefully leave a crater. Although the Tunguska event of 1908 and Vitim event of 2002 are thought to be caused by ‘meteor impacts’, no one has ever found a crater. Even though the Tunguska one supposedly felled
an estimated 60 million trees over 2,150 square kilometers. It does not count, no crater/structure, no inclusion, sorry.
The most recent impact event in history however, that did leave a ‘hole in the ground’, happened on 10:30 in the morning on February 12, 1947. It happened in a sparsely populated area in eastern Russia. But nonetheless it was seen by many an eye-witness. It is the Sikhote-Alin impact event. In fact it left a bunch of holes in the ground, with the largest one measuring up to 26 meters and 6 meters deep. (It is estimated that of the original 100 metric-ton bolide, only 27 metric-ton ever reached the surface of the earth.) For an artist impression see the picture on the left.
On a side-note: The event was commemorated with a postage-stamp. And pieces of the iron-meteorite are being sold on ebay!
So what about other ‘humanly’ witnessable impact events? Let’s say humans/hominids where around some 5 million years ago (written history dates back some 4000 years?). At least 35 confirmed impact events happened in the past 5 million years. Some of them 10 kilometers wide. So if you care to wonder, some impacts may have been witnessed by our forefathers, leaving an impression that somehow may have entered our collective conscience. (Probably not.)
If you wonder, like me, what kind of impact events our forefathers may have witnessed (or even killed). Here’s the Most Recent Impact Structures KML (Google Earth needed).
The oldest impact structures
Where there’s a ‘most recent’ there must be an ‘oldest’. Thus in the same fashion I present you ‘the oldest impact structures on planet Earth‘.
Mind you these are impacts are so old as… well… before there was any dinosaur ruling the earth, there was something else. But 2 billion years ago there was probably nothing more than bacterial soup. So no humans were harmed, but the sheer size of the impacts may (or may not) have impacted the course of evolution. Who knows?
Enjoy! (And wonder…)