帮我分析呀hours are marked by changes in the face of

帮我分析呀hours are marked by changes in the face of
Night is a dead and monotonous period under a roof; but in the open world it passes lightly,with its stars and dews and perfumes,and the hours are marked by changes in the face of Nature
marked by到底是什么呀 怎么change in the face of Nature
都说的有道理 我该给谁分呢