Historians often debate questions of when people first came to Ireland,
and theorize what race of people(s) were first to arrive.
We know little about Ireland a million years ago.
The cenozoic period started 70 million years ago and continues
today. Now the earth has experienced about 20 Ice Ages, each producing large
continental size ice sheets which enveloped land wherever they went.
Starting 40,000 years ago we know substantially more; Ireland was
heavily forested and mountains were taller.
This profile began to change 30,000 years ago with the onset of the
last and current ice age. Sheets of ice marched inexorably from the
Scandinavian arctic south for 10,000 years to finally lock Ireland in it's
icy grip. The glaciers extended south to Munster, but left Cork and Kerry
relatively ice free.
20,000 years ago the ice started to melt and the ocean began to rise
from 400 feet below sea level up to present level.
Then Galway Bay was a fresh water lake and the Aran Islands sat on a
limestone shelf 100 to 400 feet thick forming an ocean blocking arc of
burren limestone connecting the land south of Galway with the land north of
Sometime around 9,000 years ago the temperature of Ireland became
people friendly and from that point on could theoretically support
Read about ice age Ireland here.