The most obvious events marking the passage of time were the rising and setting of the sun and its continuous apparent motion from east to west through the sky.
(The most obvious events; marking; the passage of time) (The most obvious events marking the passage of time; were; the rising and setting of the sun and its continuous apparent motion from east to west through the sky)
The most obvious events The most obvious events marking the passage of time
marking were
the passage of time
the rising and setting of the sun and its continuous apparent motion from east to west through the sky