In Chapter 4, Roger and Maurice have just been released from their shift in tending the signal fire, so they make their way toward the beach. Roger, who is a natural bully, heads not to the water to swim, but instead goes through the sandcastles Henry, Percival, and Johnny have made, "kicking them over, burying the flowers, scattering the chosen stones." Maurice, a natural imitator, follows along and "added to the destruction."
The little boys don't actually mind that their creations have been leveled because they have moved on to other interests. Percival starts crying because he got sand in his eye, and this is enough to cause Maurice to feel guilty, so he hurries away to go take a swim. Not having obtained the reaction he wanted, Roger follows Henry, who wanders down along the beach. Keeping himself hidden, Roger begins to throw stones at Henry, but he throws to miss.
Interestingly, Henry gets involved with playing with the tiny water creatures that the tide is bringing in. He traps them in little pools and "became absorbed beyond mere happiness as he felt himself exercising control over living things." Likewise, Roger is trying to exercise control over the littluns. Henry's game with the sea creatures "gave him the illusion of mastery." Roger, too, is enjoying his feeling of power over something (someone) smaller as he throws the stones around Henry without letting him see where they are coming from. As the novel progresses, Roger's lust for power becomes stronger and stronger until he finally ends up rolling the boulder on top of Piggy and killing him.
In Chapter 4, a few of the littleuns are making sand castles. They have made a bunch of them on the sand bar and the mouth of the little river.
While they are doing that, Roger and Maurice come along and destroy the sand castles by kicking them over. They also scatter the rocks and flowers that the littleuns have been using.
This shows that Roger, especially, is getting less civilized. However, we will find out a bit later in the chapter that he has not completely broken from civilization because he is unwilling to actually hit Henry with the rocks he throws.