In southern Alberta, scientists have found a vast, ancient crater that they claim dates back some 50 to 70 million years. Discovered entirely by accident in near the hamlet of Bow City, some 20 km south-west of Brooks, and 100 km south-east of Calgary. According to assessments of the impact zone, researchers estimate that the space rock would have been the size of an apartment block, and would have left a crater 8 kilometers wide and roughly 2 and half km deep.
All told, this explosive force of this impact would have been 200 times stronger than the most powerful thermonuclear bomb ever built. That’s basically a force of 1000 megatons, a detonation so powerful that anything within 200 km of the impact would have received 1st-degree burns. To put that in perspective, this means that the city of Calgary would have been decimated by the blast, and in Edmonton, some 400 km away, every window would shattered.
But even more awe inspiring was the long-term effects of the damage, which would have thrown enough dust and debris into the atmosphere to mess with the Earth’s climate for the next few years. As Schmitt put it:
Something of that size, throwing that much debris in the air, potentially would have global consequences; there could have been ramifications for decades.
But after eons of erosion, very little of the crater is left. In fact, the discovery happened entirely by accident when a geologist – who was doing some routine mapping of the underground layers a few meters beneath the surface – apparently noticed a circular disturbance that was covered. Schmitt and his lab were called in to inspecting the feature and used seismic data to create a complete image of it. They quickly realized that it was most likely an impact crater, complete with a central peak where the meteorite would have struck.
The size of the object can only be estimated, but assuming the meteor was composed mostly of iron, it would have had to have been between 300 and 500 meters in diameter to create a crater of this size. If the meteorite was rock, it would have had to have been a kilometre across. Schmitt said the crater is a rare opportunity to study the floor of an impact crater. His team is now looking for certain types of minerals that form only under certain conditions so as to confirm the crater is from a meteor impact.
But he doesn’t have much doubt. As he put in a recent interview with CBC news:
We’re able to get at the lower parts of (a crater) and see how rocks have been moved around… We’re pretty confident it can only be a meteorite impact. It’s pretty clear.
Once they’ve had a chance to uncover and examine the area in greater detail, a clear picture of the meteorite’s size, composition, and what lasting marks its impact left beyond the crater. This information will only contribute to our understanding of our Solar System, but of the history of our planet as well.
Sources: cbc.ca, calgarysun.com