What lines in Lord of the Flies describe the setting?

The entire book takes place on the unnamed island in Lord of the Flies. There are two different sides to the island itself. When Chapter One first opens, the reader sees the island immediately after all of the boys crash land upon it. The previous night's storm has carried the wreckage of the plane out to sea and it has left a "scar" on the island in its wake. Chapter One begins in the island's jungle, but the boys quickly make their way out to shore. 

The shore was fledged with palm trees. These stood or leaned or reclined against the light and their green feathers were a hundred feet up in the air. The ground beneath them was a bank covered with coarse grass torn everywhere by the upheavals of fallen trees, scattered with decaying coconuts and palm saplings. (10)

Although the island is described as being relatively small, there is a mountain, which allows a person standing on its highest peak to see the entire island. From that vantage point the island is described as: 

It was roughly boat-shaped: humped near this end with behind them the jumbled descent to the shore. on either side rocks, cliffs, treetops, and a steep slope: forward there, the length of the boat, a tamer descent, tree-clad, with hints of pink: and then the jungly flat of the island, dense green, but drawn at the end to a pink tail. There, where the island petered out in water, was another island; a rock, almost detached, standing like a fort, facing them across the green with one bold, pink bastion. (29)

The island is also described as having two sides. One side is welcoming, warm, and contains a jungle with fruit trees. The boys live on that side of the island during the first half of the book. There is a tiny lagoon with warm water that they use for relaxation and swimming and a sandy beach on that side. The other side of the island is harsher and almost feral. The rocks on that side of the island have formed a peninsula that the boys refer to as a castle. They view it as a fortress of sorts, since it's only approachable from one side. 

He was surrounded on all sides by chasms of empty air. There was nowhere to hide, even if one did not have to go on. He paused on the narrow neck and looked down. Soon, in a matter of centuries, the sea would make an island of the castle. On the right hand was the lagoon, troubled by the open sea; and on the left - (105)

The island, much like the boys themselves, possesses two natures: a civilized, kinder side, and a harsher and savage side.