Geology is what helped keep the main types of New Caledonia Jurassic and Cretaceous vegetation.
The Grande Terre of New Caledonia broke away from Gondwana continent (which grouped the lands which after breaking apart formed Australia, Antarctica, South America, India, Madagascar and Africa) about 85 million years ago (at the end of Cretaceous). As the Noah ark this upper cretaceous New Caledonia took on board the flora of these times. Soils on the ultrabasic rocks (terrains "miniers"), to which this flora subsequently adapted (about forty million years later), being toxic or insufficiently mineralized for most modern plants, became a refuge for many of the original flora species.
Grande Terre of New Caledonia has thus isolated and preserved an important part of the main types of the ancient flora, particularly on the ultrabasic massifs. These massifs are like an archipelago in the island, they carry the primitive vegetation but with a specificity unique for each massif. The ancient flora occurs also in New Caledonia mountains rain forests.
This unique set of events explains why New Caledonia's flora is so original and particularly rich in primitive groups.
"Many vegetal taxons of the current New Caledonian flora, appear, because of their archaic characteristics, as primitive forms belonging to ancient groups which have lasted without important changes until today. They are the remnants of ancient lineage, true relics of Gondwanaland cretaceous flora and can be qualified as living fossils." (Aubréville, A., 1975. - La flore australo-papoue, origine et distribution. Adansonia, 15 (2) : 159-170).
The endemic vegetation of New Caledonia is heir of the vegetal world of the dinosaurs. ( Dinosaurs disappeared at the end of the Cretaceous at the limit between Secondary and Tertiary eras.
Jean-Jacques Espirat