What is the summary of chap 23 the lost the dark ground?

Robert,Cam,Zak and Nate were on their way to Robert's home and they were very tired.Robert struggled to walk he was exhausted.He ate nut meal and lay beside a tree.Afterwards they were trying to cross a gorge.They went inside the gorge to find food.They found a snail and tried to kill it for food.Robert bravely killed it with his spear.Then they ate it.