Mountain Top Mystery - Gertrude Chandler Warner

Henry, Jessie, Violet, and Benny used to live alone in a boxcar. Now they have a home with their grandfather, and are spending the summer mountain climbing in New England. A dangerous rockslide, a mountain cave, and a secret treasure are a few of the adventures in store for the boxcar children! Marooned on a mountain, the Aldens survive a landslide and find a Native American secret.