Two teams of engineers, one funded by the state of Louisiana and one based at the University of California, Berkley, have previously put the blame on the Army Corps of Engineers and on a weak layer of ground below the canal walls.

NPR: Panel's Report Assigns No Blame in Levee Failures

The latest developments concerning the new ground were not expected to be an issue as Layer Road has been fit to host the club for the last 70 years.

BBC: Colchester should be in their new home by 2008

"An inversion layer is keeping the smoke close to the ground, limiting visibility and reducing helicopter air operations, " Berry said.

CNN: Firefighters make headway in California wildfire

This autonomous, solar-powered robot carries a ground-penetrating radar to study how snow accumulates, adding layer upon layer to the ice sheet over time.

ENGADGET: NASA's GROVER eco-rover to examine Greenland's ice sheet (video)

Interestingly, Mr. Davis has cited the importance of layered or "tiered" defense among his rationales for restarting the canceled E2I secondary interceptor for the single ground-based defense site he advocates -- despite the fact that the E2I system does not represent an independent layer.

CENTERFORSECURITYPOLICY: Center For Security Policy