Palisade is a fortiﬁcation wall made of tall wooden stakes, or palings, and has its origins in the Latin word palus. Geologically, a palisade is a tall, inaccessible cliff of column-shaped basalt. Palisades are formed when a sill—a thick volcanic ﬂow that has forced its way through two layers of sedimentary rock—becomes exposed by a combination of uplifting, faulting, and erosion. As a result particularly of water erosion, palisades are often found bordering a lake or river, such as the spectacular Hudson River Palisades across from New York City. Rising as much as ﬁve hundred feet and extending for ﬁfty miles, these palisades are magisterial in their solidity. Their raw geometry and primitive power stand in stark contrast to the steel, glass, granite, and sandstone palings of Manhattan and are reminders of the enduring forces that shape the surface of the planet and the temporal quality of human ediﬁces.