Linked from
The 12 pages that link to Lunar highlands, each with the reason it gives.
Lunar regolithRelated: Highland regolith differs from mare soil in age and mineral composition.
MoonBroader topic: They preserve some of the oldest exposed crust on the Moon.
AnorthositeBroader topic: Their plagioclase-rich crust is a planetary-scale example of anorthosite.
Earth's MoonBroader topic: They preserve some of the oldest exposed terrain on the Moon.
AnorthiteRelated: Their ancient crust contains abundant anorthite-rich plagioclase.
Pre-NectarianRelated: Highlands preserve much of the Moon’s exposed early crust.