Younger Dryas Boundary event debunked once again

At http://phys.org/print254421869.html … a new study, by the US Geological Survey, claims it has found evidence that elevated levels or iridium, magnetic spherules and titanomagnetic grains, usually thought to be impact markers, have a more than likely terrestrial origin. No comet broke up over North America, they say, but we might ask, is this the kind of evidence we might expect of uniformitarian orthodoxy repudiating the YDB event mainly as it does not equate with their belief system as regards the past history of the Earth, or is this serious scientific scepticism. Basically, they are saying that the so called black mat layers are widely distributed and are not solely confined to the Younger Dyras event so they cannot be cosmic and similar mark material accumulated naturally in swamps and bogs. Over at http://cosmictusk.com/breaking-new-study-claims-black-mat-materials-comm… .. is George Howard's response and his line is that the geologists have fundamentally misunderstood the YDB team's stance. They do not claim the blast materials came from space. Their position is that they are terrestrial and the Mexican paper a few weeks ago reiterated their position – so why are these people saying otherwise? Did the geologists actually read any of the papers concerning the YDB impact theory or did they begin on an assumption they knew what those papers had said solely on the basis that detractors have been repeating the false manatra for some time. It seems unlikely as surely serious scientists would check out what they were critiquing. However, the other alternative is that it is a purposeful ploy to concentrate on a fallacy of their own invention, a tactic widely used by the co2 doomsayers in the climate debate.