This is a place that Ruby apparently goes in when she wants to be alone to think. She goes to this place in the third episode: The Star Day Celebration.
From what they have shown in this episode, it has a large spot in front with a good view of the Great Valley and has a small cave as well.
It is during this episode while Ruby is there that an earthshake happens that makes a part of the area that Ruby likes to sit breaks off and falls onto the enterance which she is trapped until being rescued within the cave. Though since the gang can stand in front of the cave entrance, it seems that Ruby could still go here to use it, though the area in front of the cave is a little smaller after this episode.
Ruby's Thinking Place has appeared in the third episode of the LBT TV series called 'The Star Day Celebrations' which Ruby apparently goes in if she wants to be alone to think. The episode had the location with a large spot in front with good views of the Great Valley and has a small cave as well.
An earthshake that appeared in the first LBT film trapping Littlefoot & Cera from their families before, happened which one part of the area that Ruby likes to sit on, breaks off and slams itself on the enterance, getting her trapped. The gang can stand in front of it which they seem Ruby could still use it but the front of the cave turns smaller after the episode ends.
The Star Day Celebrations is the third episode between the second episode called 'The Mysterious Tooth Crisis' and the fourth one, 'The Canyon of Shiny Stones'.