What happened to the wings of Michael Schumacher?

http://www.formula1.com/gallery/race/2011/848/review.html

In the last picture, you might see the wing with some dirty stuffs. By its colour of black and appearance, the dirt might be some carbonates, which is oil etc. Then, why is there such industrial dirt than sand or soil which is plenty around the course? We can think very few candidates possibly to be on the circuit. Oil from car, debris from the car body (carbon fabricate), and the part of tyres. In this season, we have seen the shortness of endurance of Pirelli tyres. At the backstraight of the China, we could see rolling little pieces of rubber which considered to be from tyres after and after from the series of cars. So, the debris taken out from the tyre is considered to have to be some 'pieces'. However, considering the basic mechanism of how tyre works, the surface of circuit is attached with melted rubber from tyres. Usually they stick on the surface so on the most of cars we cannot see such dirt. However, seeing the picture, we can see how Pirelli tyres are easy to melt, which is softer than Bridgestone.