Rib Mountain, formerly called Rib Hill, is a four-mile-long ridge of ancient rock dating back about 1.7 billion years. It is among the oldest geological features on earth. It is composed of a very hard metamorphic rock called quartzite.
For many years, it was believed to be the highest point in Wisconsin. Now it's generally accepted that Timm's Hill, near Ogema in Price County, is the highest at 1,952 feet above sea level and Rib Mountain is fourth at 1,924 feet above sea level. However, Rib Mountain does stand higher above the surrounding terrain, 670 feet, than any other hill in the state.