William Golding's novel Lord of the Flies is quite symbolic, so anything which plays a significant role in the novel also has a significant symbolism to be examined. The answer above, given by tropicof, is excellent; I would only add several other considerations.
The first description of the jungle which Golding gives us is the image of the scar: "All round him the long scar smashed into the jungle was a bath of heat." Despite the lush beauty of this tropical setting, it is the scar which Golding immediately highlights, setting the tone for the rest of the novel.
The three boys who explore the mountain (Ralph, Jack, and Simon) can clearly see the scar from above; throughout the novel, these three characters are the most aware that something is wrong on this island. Ralph has trouble articulating the evil he senses, but he knows it exists, like the scar. Simon, too, recognizes the evil and is able to identify it as themselves; however, no one listens to him. Jack is less obviously aware that things are not right on the island (probably because he is the primary cause of the evil), but he has just been shocked that he was not elected chief (something which was a given in his mind), so he is wounded and aggressive.
The scar is also a symbol of what happens when something beautiful is destroyed, and other examples of that can be found throughout the novel: the innocent little boy with the mulberry birthmark who died in the initial fire, the sensitive Simon who only wanted to share his revelation with everyone, the intelligent boy (Piggy) who was ignored and tormented because of physical attributes, some of which were beyond his control.
The other children will go on to live their lives but will always carry the scars of this experience.