What does Zelda use as a metaphor for the passage of time in the book, Z: A Novel of Zelda Fitzgerald?

Rivers symbolize life and the passage of time, as Zelda feels life has pulled her down a metaphorical river that she could not pull herself out of. Thus, rivers also symbolize the turbulence of Zelda’s life, which she felt powerless to fight against. Zelda says both her and Scott were stuck in a metaphorical river, as the waters left them confused until they were surprised to see just how much time had passed by; they find themselves separated from one another after an eventful and difficult marriage.