The film begins with a saber-toothed squirrel (known as Scrat) who is trying to find somewhere to store his prized acorn. Eventually, as he tries to stomp it into the ground, he causes a large crack in the ground that extends for miles and miles and sets off a large avalanche. He barely escapes, but finds himself stepped on by a herd of prehistoric animals. The animals are trying to avoid the ice age by migrating south, except for Manfred, an agitated mammoth who is heading north. Sid, a clumsy Megalonyx sloth left behind by his family, decides to go on by himself and angers Carl and Frank, two Brontops by ruining their salad and is attacked. Sid is soon saved by Manfred, who fights them off. Not wanting to be alone and unprotected, Sid follows Manfred.