Rock Doc

By DR. E. KIRSTEN PETERS

On a lark, when I was a college student I took a class in field biology. It sounded romantic and I was young, so even though it didn't really make any sense for a geology student to take the senior level class in another discipline, I was there bright and early on the first day of the semester.

One week everyone in the course walked to a grove of old hardwood trees near the edge of campus. We had "boring tools"- - drills with long, hollow bits -- with us. The idea was to sink the bit into the trunk of the tree. When the bit reached the middle of the tree, we used a nar...