A
wrinkle ridge is a type of feature commonly found on
lunar maria. These features are low, sinuous
ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are
tectonic features created when the
basaltic lava cooled and contracted. They frequently outline ring structures buried within the mare, follow circular patterns outlining the mare, or intersect protruding peaks. They are sometimes called
veins due to their resemblance to the
veins that protrude from beneath the skin. These are found near craters.