After Jack quits Ralph's group, he establishes his own tribe of savages on the opposite end of the island. Jack's headquarters are located on the top of Castle Rock, which is an ominous, desolate place. Castle Rock is a large, steep rock formation jutting out of the treacherous sea, which is connected to the island by a narrow walkway about fifteen-feet long. Jack protects his headquarters by placing savages as lookouts at the edge of the precipice and has logs placed underneath massive boulders that can be rolled from above onto intruders. In chapter 10, Roger attempts to climb Castle Rock and is stopped and questioned by Robert, who acts as the lookout on the top of the rock formation. After giving Roger permission to enter, Robert shows him their defenses used to protect the headquarters. Golding writes,
"A log had been jammed under the topmost rock and another lever under that. Robert leaned lightly on the lever and the rock groaned. A full effort would send the rock thundering down to the neck of land. Roger admired" (228).
Essentially, there are numerous boulders located on the top of Castle Rock that the savages strategically use to roll down the precipice towards intruders. In chapter 11, Roger rolls a large boulder towards Piggy from the top of Castle Rock that ends up crushing him to death.