[7] Farming and grazing reduced the island's original vegetation cover by around 90%, before being made a wildlife sanctuary in 1966 and a nature reserve in 1997.

While most attention has focused on the tuatara, the significant and unique factors include: In natural character, Stephens Island is a rugged landmass dominated by maritime influences.

From sea level the lighthouse is a prominent visual feature, while from the air the cluster of buildings and farmed landscape are obvious.

The surrounding sea is rich with marine life, albeit strongly modified and depleted by fishing, and historically by hunting of whales and seals.

Indurated with widespread metamorphic prehnite, pumpellyite, and lawsonite, the formation is subdivided into Queens Beach, Incline, Takapourewa, and Titapua Members, with no discernible top or bottom boundaries.

Notably, the oldest rocks, found in the Queens Beach Member, consist of a 150-meter layer of rounded cobble conglomerate enclosing angular blocks of coarse volcanogenic sandstone.