The largest crater in the United States can be found in the Chesapeake Bay. Roughly 35 million years ago the Appalachian Mountains were covered in tropical rainforests. Little critters wandered about when a mile-wide rock or chunk of ice traveling at supersonic speed crashed into the Atlantic Ocean off of North America. Ocean water and rocks were thrown 30 miles into the sky. Everything within a few hundred miles of impact on the East Coast was incinerated. The force of the impact spawned tsunamis hundreds of feet tall that smashed into Blue Ridge Mountains (maybe the tsunamis were even taller than the Blue Ridge Mountains). When all was settled, a 56-mile-wide crater formed in the floor of the Northern Atlantic Ocean.
Scientists believe that this asteroid or comet impact, along with others, largely contributed to the Oligocene extinction, which severely affected land mammals.
The extinction is believed to have been caused by climate change. Records show that temperatures were relatively warm around 35 million years ago. Based on geologic data, it is believed that between 36 and 34 million years ago a comet/asteroid shower occurred on Earth. Suddenly around 34 million years ago records indicate the Earth cooled rapidly. By 33.4 million years ago the Oligocene extinction took place. Scientists theorize that the multiple impacts of asteroids and comets caused prolonged darkness, wildfires, and acid rain. These events led to the mass extinction and the rapid cooling.
The extinction is believed to have been caused by climate change. Records show that temperatures were relatively warm around 35 million years ago. Based on geologic data, it is believed that between 36 and 34 million years ago a comet/asteroid shower occurred on Earth. Suddenly around 34 million years ago records indicate the Earth cooled rapidly. By 33.4 million years ago the Oligocene extinction took place. Scientists theorize that the multiple impacts of asteroids and comets caused prolonged darkness, wildfires, and acid rain. These events led to the mass extinction and the rapid cooling.
Now back to the Chesapeake Bay Crater. Recently, scientists drilling over a mile down into the crater discovered something absolutely astounding. The drill poked into a pocket of water deep in the Earth. This is not just any water, this water is 100 to 145 MILLION years old. It is trapped over a mile underground in an area of about 60 square miles.
The water was in the sediment long before the impact occurred and was trapped by folding and faulting that took place when North America broke away from Europe. The impact of the object only stirred the water but did not allow it to seep out. The water is very salty- twice as salty as modern seawater. The problem with this is that the aquifers for groundwater in the area are highly susceptible to contamination by this extremely salty groundwater just below. With such a large population to support, this is concerning.
The water was in the sediment long before the impact occurred and was trapped by folding and faulting that took place when North America broke away from Europe. The impact of the object only stirred the water but did not allow it to seep out. The water is very salty- twice as salty as modern seawater. The problem with this is that the aquifers for groundwater in the area are highly susceptible to contamination by this extremely salty groundwater just below. With such a large population to support, this is concerning.
The crater itself also has dramatic impacts (no pun intended); local rivers and even the Chesapeake Bay are severely influenced by the crater. The depression of the crust of the Earth due to the crater predetermined the course of rivers and the location of the Chesapeake Bay. In addition, the crater is contributing to the sinking of land near the Bay. The coast is literally slipping into the crater.
The importance of this discovery of this water cannot be underestimated. The analysis of the ancient seawater will provide insight into the evolution of life. In addition, it will help scientists understand how salty ancient seawater was to gauge the threat of modern ocean acidification. Moreover, it is really cool.
Thanks for reading.
Sources:
https://www.uwgb.edu/dutchs/EarthSC102Notes/102PTEarthHist.htm
http://www.nature.com/nature/journal/v503/n7475/full/nature12714.html
http://news.nationalgeographic.com/news/2001/11/1113_chesapeakcrater_2.html
The importance of this discovery of this water cannot be underestimated. The analysis of the ancient seawater will provide insight into the evolution of life. In addition, it will help scientists understand how salty ancient seawater was to gauge the threat of modern ocean acidification. Moreover, it is really cool.
Thanks for reading.
Sources:
https://www.uwgb.edu/dutchs/EarthSC102Notes/102PTEarthHist.htm
http://www.nature.com/nature/journal/v503/n7475/full/nature12714.html
http://news.nationalgeographic.com/news/2001/11/1113_chesapeakcrater_2.html