you are likely to find Stone in/at/on Cave. you are likely to find Snake in/at/on Cave. you are likely to find Snake in/at/on Pit. 
Gaze is a type of Look. Observation is a type of Look. 
Stone --AtLocation--> Cave <--AtLocation-- Snake --AtLocation--> Pit 
Gaze --IsA--> Look <--IsA-- Observation 