What geographic term is used for markings that may be located on a horse's legs?

The geographic term used for markings that may be located on a horse's legs is "Sock." In equine terminology, a sock refers specifically to a white marking that extends from the horse's hoof up to some point on the leg, generally covering a portion of the cannon bone. This marking is common and can vary in height and size.

In contrast, terms like dorsal stripe, bald face, and blaze refer to markings found in other areas or are different in nature. A dorsal stripe runs along the back of the horse, a bald face covers a significant portion of the face, and a blaze describes a wide stripe down the horse's face, but none specifically describe leg markings. Hence, sock is the correct answer as it specifically pertains to leg markings on horses.