It may be the most disturbing site yet: the first heavy sludge now oozing into the marshes of Louisiana as the slick continues to grow in size out in the gulf.
CBS News correspondent Kelly Cobiella reports it's an ominous sight. The oil is thick and black and stretches about a quarter mile down a beach. It goes beyond the booms into the sensitive marsh lands which are home to migratory birds.
Louisiana Gov. Bobby Jindal flew over it Tuesday.
"This wasn't just sheen, we were seeing heavy oil out there," Jindal said. "This wasn't just tar balls. It shows you how quick the oil showed up."
When CBS News tried to reach the beach, covered in oil, a boat of BP contractors with two Coast Guard officers on board told us to turn around under threat of arrest. Coast Guard officials said they are looking into the incident.
The impact on wildlife is unclear. Government officials say that 162 sea turtles have died, about half a dozen bottle nose dolphins have died. The sea turtles have not been thoroughly examined yet but federal officials say this seems related to the oil spill. And they admit they have no idea what's happening in the deeper waters because they can't watch it.
Special Section: Disaster in the Gulf
Under Pressure from Congress, BP Releases Video
Were Oil Rig Warnings Ignored?
Oil Spill by the Numbers
Also on Tuesday, nearly two dozen tar balls were found off Key West, Fla., the U.S. Coast Guard said, but the agency stopped short of saying whether they came from the massive oil spill.
Some 5 million gallons of crude has spewed into the Gulf and tar balls have been washing ashore in several states along the coast.
Government scientists are surveying the Gulf Coast to determine if oil has entered a powerful current that could take it to Florida.
National Oceanic and Atmospheric Administration Administrator Jane Lubchenco says aerial surveys show some tendrils of light oil close to or already in the loop current, which circulates in the Gulf and takes water south to the Florida Keys and the Gulf Stream. But most oil is dozens of miles away from the current.
Lubchenco says it will take about eight to 10 days after oil enters the current before it begins to reach Florida. But scientists from the University of South Florida are forecasting it could reach Key West by Sunday.
The Coast Guard said the Florida Park Service found the tar balls on Monday during a shoreline survey. The balls were 3-to-8 inches in diameter.
Coast Guard Lt. Anna K. Dixon said no one at the station in Key West was qualified to determine where the tar balls originated. They have been sent to a lab for analysis.
© 2010 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.