How was the assembly area in chapter 5

From the text:

The place of assembly in which he stood was roughly a triangle; but irregular and sketchy, like everything they made. First there was the log on which he himself sat; a dead tree that must have been quite exceptionally big for the platform. Perhaps one of those legendary storms of the Pacific had shifted it here. This palm trunk lay parallel to the beach, so that when Ralph sat he faced the island but to the boys was a darkish figure against the shimmer of the lagoon. The two sides of the triangle of which the log was base were less evenly defined. On the right was a log polished by restless seats along the top, but not so large as the chief's and not so comfortable. On the left were four small logs, one of them--the farthest-- lamentably springy. Assembly after assembly had broken up in laughter when someone had leaned too far back and the log had whipped and thrown half a dozen boys backwards into the grass. Yet now, he saw, no one had had the wit--not himself nor Jack, nor Piggy--to bring a stone and wedge the thing. So they would continue enduring the ill-balanced twister, because, because. . . . Again he lost himself in deep waters.

Grass was worn away in front of each trunk but grew tall and untrodden in the center of the triangle. Then, at the apex, the grass was thick again because no one sat there. All round the place of assembly the grey trunks rose, straight or leaning, and supported the low roof of leaves. On two sides was the beach; behind, the lagoon; in front, the darkness of the island.