A fascinating survey of the impact of human development as seen through the strata of Walden Pond, located right here in Concord, Massachusetts. The author notes:

“In “Walden,” Thoreau wished for a fanciful “realometer” to cut through the “slush of opinion, and prejudice and tradition … to a hard bottom.” My own realometers are made of soft lake mud.”

A big “aha” for me was to learn if you stick your fist in the mud, pretty soon you’ll touch a layer of cesium 137, which is found at that layer in every body of water on Earth (you’ll need to read the article to learn why it’s there). It’s an eerie reminder of how everything we do matters, and a helpful signal to be mindful of how we will contribute to future layers of the silt in Walden Pond.