Published time: October 17, 2013 22:50 Fire boat response crews battle the blazing remnants of the offshore oil rig Deepwater Horizon, off Louisiana, in this April 21, 2010 file handout image. (Reuters/U.S. Coast Guard/Files) The US Coast Guard has discovered a 4,100-pound tar mat under the sand around Louisiana’s southernmost port. It is believed to … Continue reading New mass of tar on Louisiana coast linked to 2010 BP oil spill