What surprised you the most when writing The Guide?

During my research, I kept being jarred by the discrepancy between Thoreau’s description of the pond shore in the 1840s and 1850s and what we can see today.   I have long since known that the vast swimming beaches of the eastern shore were created from whole cloth by massive excavation and the importation of excavated sand.  What I had not realized before this project was that the bulk of the natural perimeter has been changed as well. Thoreau’s stony shore is largely gone; being partially buried, and partly lost due to human inattention.  The simple fun of tossing stones into the water or skidding them onto the ice is actually an an important agent of denudation.  I contributed to this problem myself before calculating the cumulative effect of pitching stones away from the shore.