Science is awesome. I recently read “Chesapeake Invader: Discovering America’s Giant Meteorite Crater” by C. Wylie Poag. For a book about science, it is well-written, easy to read and thoroughly explains a fascinating topic, namely “America’s largest meteorite impact crater.”
Though the crater was formed 35 million years ago, it continues to influence Virginia and the Chesapeake Bay. So many mysteries about our region can be tied back into that catastrophic event.
It is humbling to contemplate the force required to excavator 50-mile-wide crater to a depth of more than a mile, and then fill it back up again with breccia, all within a couple of minutes or hours, or at most, a few days. Computer simulations and comparisons with nuclear explosions show the rapidity of successive of events in impacts of this magnitude. It punched into the seafloor with a force equal to 10 trillion tons of TNT – a natural holocaust of colossal proportions. The blast wave alone would have instantly incinerated all higher life forms within 600 miles of the impact site.
- Breccia: “Rock composed of irregular, angular fragments of preexisting rocks mixed together into a matrix of finer-grained particles.”
It took evolution nearly 4 billion years to turn primitive aquatic bacteria into the complex, interactive communities of the Eocene. Thirty-five million years ago may seem like an eternity to us short-lived humans, but it was only yesterday in the grand scheme of organic evolution. If we imagine that life on Earth begin only one year ago, the late Eocene would have begun only three days ago.
These geological and topographical features are not the only evidence of a buried crater’s residual effects. I’d you examine a map of the Chesapeake Bay region, you will notice something strange about the courses of two major rivers that enter the bay. The Rappahannock and other rivers north of the crater take a nearly direct southeasternly route to the bay. But the James River takes a quite different route. As it approaches the bay, the James makes a sharp right-angle bend to the northeast just as it crosses the buried crater rim, and flows directly toward the crater center. The York River does the same thing. The lower course of each appears to be controlled by the crater’s location, though the rim is buried 1,000 feet below.
An Air Force telescope on Mount Haleakala in Maui, Hawaii, detected more than 10,000 asteroids. Ninety-nine of them are larger than half a mile in diameter and orbit within five million miles of Earth. This is the dangerous category. The estimated total in the dangerous half-mile size range is 1,500. An asteroid this large is expected to strike Earth an average of once every 150,000 years.