One device that Golding uses in Lord of the Flies to build suspense is setting imagery, particularly that related to the weather and nature. For example, at the beginning of Chapter 4 "Painted Faces and Long Hair," Golding opens the chapter by describing the scenic details of the course of the day. Then he describes the sea:
Strange things happened at midday. The glittering sea rose up, moved apart in planes of blatant impossibility; the coral reef and the few stunted palms that clung to the more elevated parts would float up into the sky, would quiver, be plucked apart, run like raindrops on a wire or be repeated as in an odd succession of mirrors.
Piggy claims that scenes like this are just mirages, but they build suspense for the reader who senses that the weather and the scenes of nature are really symbols for the events to come on the island. The natural backdrop of the island sets the tone for the events in the novel, so unsettling scenes such as the one above suggest to the reader that something equally unsettling is coming in the novel. And of course later in this chapter, Jack and his hunters show up with their faces painted similar to war masks, signaling the divide between his group of hunters and the boys who are still under Ralph's leadership.