One example of savagery in the book is when the boys make the fire. They run up the mountain like animals, while Piggy yells at them about how they are a crowd of immature kids.
I've got the conch!
Another example in the book is when Jack and his tribe have a feast and reenact the killing of the pig. However, the boys savage motives, and careless timing, ends up killing Simon.
You voted for me as chief. Now you do what I say.
The symbol of savagery in the book, Lord of the Flies, is the pig head that Jack and his tribe kills. This is because the pig and his meat was Jack's priority the whole the boys were on the island.
One example of civilization is when Piggy argued over having the conch at one of Ralph's called meetings. He reminds everyone that when a person has a conch, they have a right to speak.
Another example of civilization is when Ralph calls another meeting and tells them that he was selected as chief and they need to follow his rules because they are being unsanitary.
The symbol that represents civilization is obviously the conch that they use in the book for calling meetings and for speaking. The conch creates order and a civilized manner while the boys are at the island.