How does Caryl Phillips use imagery in Crossing the River?

Example of Imagery:

"...it was the African fever, or malaria, which most affected the lives of the settlers. The severe chills, producing a sensation of cold as fearful as any American winter, and the accompanying delusions which infected the imagination, combined to introduce a deep misery."

"Curling herself into a tight fist against the cold, Martha huddled in the doorway and wondered if tonight she might see snow. Beautiful. Lifting her eyes without lifting up her head, she stared at the wide black sky that would once more be her companion. White snow, come quickly."