It was found by those evil oil companies. Nothing good can come from this.
Those evil oil companies supplied the data that enabled the Alvarez team to discover the Yucatan meteor crater of 65 million years ago (mya). Apparently oil deposits and the extreme pressure caused by these strikes can go hand in hand. There is an apparent crater off the Brazilian coast which seems to be an oil source. Given the oil in the North Sea, this goes along with that idea. Also, multiple craters around the same time period are not unheard of. The Chesapeake (Bay) Meteor strike of 34 mya, also had companions of roughly the same age, including a 10 mile wide crater off Toms River, NJ, and a 60 mile wide crater (Popogai (sp?) in Siberia. Another comment here mentions a possible crater off Maine of the right age (65 mya).
The Chesapeake Meteor was verified by deep coring which showed breccia and shocked quartz. They also hope to find oil around there.