Geologically the Hawaiian Islands are considered to be fairly young,
probably no more than 20 million years old. The islands are also
extremely isolated from any other land masses; it is more than 2,000
miles to the nearest continent. Before any resident birdlife could exist
here, plants had to become established. Seeds arrived by various means
from distant lands, and one by one new kinds of plants began to grow on
the volcanoes—at first only a few primitive types could get a foothold
on the barren lava, but in time those early plants decayed and combined
with the basalt rock to produce a soil that could support a complex
vegetation.