The blade of his skate had nicked the ice, causing him to trip.
Big houses can depress the ice, causing water to flood the surface.
The loss of ice causes the crack to get deeper and wider.
Inspections are taking place at football grounds across Britain as snow and ice causes havoc.
Hejduk's head smashed against the ice, causing his helmet to bounce off his head.
Of course, the groove can be too deep and cause the blades to dig into the ice, causing injuries.
In southern Minnesota, freezing rain on Saturday night and Sunday morning left roads coated in ice, causing hundreds of crashes.
Charlotte police reported two people killed in separate fatal crashes early on Saturday, although investigators were still trying to figure out if ice caused the wrecks.
One of the difficulties of taking cores is that the drill bit can melt the ice, causing samples of different ages to mix.
Carsten Kengeter, Deutsche Börse's chief executive, said: "ICE caused some speculation and have confirmed that they have a certain interest in LSE but that is all they did.
