Seismic Study of Ancient Cataclysm Begins"The seismic recordings will give us a look at the subsurface rock and sediment layers, faults, and other structures produced 35 million years ago by the Chesapeake Bay impact," said USGS scientist Greg Gohn. "This ancient event probably fractured bedrock to a depth of at least 5 miles. These surveys will tell us more about the impact processes and products and their effects on ground-water resources available today in the southern Delmarva Peninsula."
United States Geological Survey
Monday, October 4, 2004
The project will involve 30 small explosions buried at depths of about 60 feet, and about 800 seismic-shotgun blasts at depths of about one foot. As energy waves from the blasts travel through the ground they will be recorded by portable seismometers placed throughout the area. Because the ground motion being recorded is less than that caused by normal daylight activities, such as vehicular traffic or vibrations from pumps, most of the blasting and recording will be done at night, usually between 10 p.m. and 3 a.m. over a 2 or 3 day period...
Scientist Rufus Catchings, who is with the USGS Western Region Earthquake Hazards Team in Menlo Park, Calif., is leading the seismic survey. He expects the high-resolution seismic imaging effort to locate crater features to depths of about one mile, and the lower-resolution survey to image structures to depths of more than 3 miles across a broad area.
Three chunks of the same asteroid, probably, formed all three of these:
http://en.wikipedia.org/wiki/Chesapeake_Bay_impact_crater
http://en.wikipedia.org/wiki/Toms_Canyon_impact_crater
http://en.wikipedia.org/wiki/Popigai_crater
Eocene–Oligocene extinction or Grande Coupure:
http://en.wikipedia.org/wiki/Eocene%E2%80%93Oligocene_extinction_event