[Guildo]

It was Sauruman that hurled the snow at them from Isengard not mordor, and i agree with Marilpajgfbvkyklaobvuy (sp) the dead Marshes where a far more complicated magic than just a spell of Sauron, like the paths of the dead which i believe to be Gondolin. Perhaps the dead marshes wher a result of Morgoths and Saurons torment and torture over thousands of years that left many angry uneasy sad gory scary unimaginable uneasy spirits but not a direct spell, and even if Sauron could do such magic when Sam and Frodo where their Sauron did have enough power to take phisical form much less mantain a magic as terrible and gutrenching as the dead marshes.

but thats just my two lembas worth