ASH TUESDAY: In their pretty dresses, front-row VIPs stood out like flowers against Chanel’s apocalyptic show set in the Grand Palais, a rocky landscape of smoking black volcanic ash. “I think dark shoes are needed to walk in for this kind of planet,” laughed Inès de la Fressange. “It’s totally crazy, I never thought the place would be this big, it’s amazing,” said Emma Roberts, who stars in the soon-to-be-released “Scream 4.” The actress said she planned to squeeze in some sight-seeing during her trip. “I’m going to enjoy some free time in Paris, then it’s back to L.A. — back to my boring life.” Delicately stepping through the rubble, Virginie Ledoyen said she is about to start filming a movie about the French Revolution. “It will be filmed in Versailles,” she said. Clémence Poésy arrived just as the show was about to start and had to watch from the nosebleed section. “I got stuck in a traffic jam,” she explained afterwards.