Slightly disconcerting: Officials in Louisiana say tar balls and oil are washing up on Gulf Coast shores across an area of more than 30 miles. Even stranger: They’re not sure where it’s coming from. Samples have been sent for testing to determine whether the oil comes from the Deepwater Horizon spill in April 2010. It’s unclear how soon results will be in. Meanwhile, the state is scrambling to get containment booms and skimmers to the area to mitigate the damage, and has asked for Coast Guard assistance. The good news? Even though oil has appeared over a large area, it’s relatively diffuse.