Foreshadowing is an important element in any drama and allows the reader to anticipate what may occur later. It also encourages the reader to continue reading to check if he is correct in his assumptions and to check for any twists in the tale.
There are many moments when a future event is hinted at, in Lord of the Flies and in chapter 6 there is the relevance of Castle Rock - which will ultimately claim Piggy's life.
The boys that enter the island see its fort potential.. and playfully roll the rocks over the edge.
It is Jack and his followers who become increasingly excited at the potential they see on Castle Rock and how it could be a fort - ironically to fight the Beast! Ralph has allowed Jack to assume control of the hunt for the beast on the unknown part of the island - also significant as, although Jack will hesitate and allow Ralph to go ahead, the descent into savagery is linked to the 'hunt' and Simon will later be sacrificed when the boys, in their frenzy, believe him to be the beast, chanting "kill the beast."
Reinforcing this is the personification of the Beast - as the parachutist floats down to the island
the figure sat on the mountain-top and bowed and sank and bowed again.
Samneric are already tense and as an excitable pair, it is not difficult for them to over- exagerrate the situation and
paint a frightening picture of the beast they believe they saw, one with eyes, teeth, and claws.
This is a classic example of foreshadowing as the beast has become so real to them that they really do imagine - right down to the scratch on Eric's face - that they were chased by the beast.
The reader knows that, even though the beast is a figment of the imagination, its essence in everyone - even seemingly innocent, well-bred, schoolboys - is very real and can be overwhelming if it is not controlled - the point that Golding primarily wanted to emphasize.
By the end of chapter 6 there can be no mistaking the important part the beast will play and Jack's increasingly important role
..undermining the frail system of the island and introducing anarchy to the boys.