Flexi Says: The lighter parts on the Moon are called terrae, or highlands (Figure above). They are higher than the maria and include several high mountain ranges. The rock that makes up the highlands is mostly composed of feldspar, which is lighter in color and crystallized more slowly than the maria. The rock looks light because it reflects more of the Sun’s light. The rocks of the terrae formed while the lunar magma ocean cooled just after the Moon formed. The maria formed later.