In Lord of the Flies, Chapter 6, where is Castle Rock mentioned?

Ralph and the biguns discovered Castle Rock in chapter six. The
castle is mentioned on page 148 when the boys were approaching the island on the hunt for the
beast.

Ralph dismissed
Simon and returned to his personal hell. They would reach the castle
some time; and the chief would have to go
forward.

Sam and Eric had been tending
to the fire when they allegedly saw the beast. The twins ran away and later informed the rest of
boys. The boys were horrified as the twins recounted their ordeal. Ralph and the older boys
decided to confirm the allegations by going to the only location where they had not explored.
Apart from the beast, Ralph was worried about the signal fire on the mountain, which was
essential for their rescue. He thus agreed to go on the hunt for the beast so they could
establish the true nature of the creature and face it once and for all. Jack led the way to
Castle Rock, which was a smaller island connected to the main island by a rocky
ledge.

He followed
Jack toward the castle where the ground rose slightly. On their left
was an impenetrable tangle of creepers and trees.

Ralph parted the
screen of grass and looked out. There were only a few more yards of stony ground and then the two
sides of the island came almost together so that one expected a peak of headland. But instead of
this a narrow ledge of rock, a few yards wide and perhaps fifteen long, continued the island out
into the sea. There lay another of those pieces of pink squareness that underlay the structure of
the island.