A sag is a depression caused by the uneven settling of the ground. The saddles and gaps of a ridge or mountain range, as well as the shallow dips in flat or mildly sloping terrain, are called sags. In cowboy jargon, the slope of a hill or mountain is sometimes called a sag. Sags frequently appear along major faults such as the San Andreas. When water collects in these fault depressions, sag ponds are formed. Lost Lake, Soda Lake, Jackson Lake, and many others strung out along the San Andreas are all sag ponds. The Illinois and Michigan basins contain sags, and the till sheets of the Midwest often give way to an undulating topography called sag-and-swell. Oddly, Sag Harbor takes its name not from the marshy depression it occupies at the end of Long Island but from the nearby town of Sagaponack, which is a transliteration of the Algonquian weg-wag-onuch (“land at the end of the hill”).

Michael Collier