In Lord of the Flies, a traumatic event takes place and a group of schoolboys, ranging in age from about six to twelve, are all stranded on an apparently deserted island, with "no grown-ups' to supervise them. Piggy, the most intelligent boy on the island and the one who will guide Ralph in his attempts to be a good leader, points out to Ralph that there is no-one to take any news of the boys back to England so they can be rescued. Before the boys landed on the island, he overheard the pilot talking about an atom bomb and so it is almost certain that everyone on the plane is dead.
The boys arrive on the island via a chute or "passenger tube" from the plane which makes a "long scar" into the landscape of the jungle. The scar has cleared away some of the dense foliage allowing Ralph to stand in the middle of it and look around. Ralph and Piggy examine the effects of the passenger tube on a "jagged end of a trunk" as it has apparently done some damage and has left a scar of its own. The chute is nowhere to be seen, however and the boys consider the possibility that it was "dragged out to sea" during a storm. It is likely that there were still some boys in it at the time but the boys try not to dwell on that possibility and they continue exploring.
It is significant that Golding calls it a scar because a scar would normally be found on the skin during or after the healing process and so the scar on the island carries its own significance as the boys must fight the forces of evil. Those who survive will carry a psychological "scar" forever.