While exploring for the first time, Venters finds evidence of beavers in Surprise Valley and realizes that he must find the the stream where they entered. Why does Venters need to see the where the stream enters Surprise Valley? What is he afraid of?

While exploring Surprise Valley for the first time, Venters finds evidence of beavers and needs to find the entrance to the stream that they live in. Venters is worried that the stream entrance may be another way to enter the valley and thus leave them open to attack.