The Arizona Daily Sun has a nice article about Dale Shewalter's life.
I was his student between 1990 and 1992 [twenty years ago!] and I remember going on field trips to mark out parts of the Arizona Trail. Mr. Shewalter loved nature, and worked hard to inculcate that love in his students. He was always trying new and innovative things in the classroom. Once we did a unit on the Colorado plateau, and each group of students made a 3D relief map of the plateau at a certain point in its history, showing how the geography had changed over time. The maps were quite large, made of paper-mâché on a 3' x 3' sheet of plywood.
I think perhaps my favorite memory is that he read the entire Hobbit and Lord of the Rings to the class, bit-by-bit. I still love those books.