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.
So you haven’t heard of the Chesapeake Bay crater? Poag and others published their discoveries in 1994 of a giant meteorite crater beneath the bay:
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.”
Can you imagine the devastation? That impact caused a mass extinction. While 35 million years ago may be difficult for man to understand, our time on Earth is so recent:
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.
Ever wondered why the James and York rivers take a sharp turn before they enter the Chesapeake Bay? If you were in the waterways, it isn’t something you’d notice, but from satellite images and maps, it is more obvious.
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.
From an urban planning standpoint, we are dealing with issues from sea level rise. Hampton Roads already was dealing with issues from the land slowly sinking (about seven inches every century) and for the past two decades, planners have been able to point to the crater as the main culprit.
Man’s time on Earth has been very short, but the potential for a mass extinction that could wipe us out is there. NASA and the U.S. Air Force are working on ways to detect the next potential collision from a large near-Earth object (NEO):
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.
On a side note, this book reminded me that the “Carolina Bay” in Windsor Farms exists. A possible remnant from when the ocean levels were much higher and the shoreline was around Richmond?
Phil Riggan 