The Saga of Pliocene Exile by Julian May
Highly Recommended

Vol 1. THE MANY COLORED LAND
Del Rey 1983
PB 429 pgs
ISBN 0-345-30989-8

Vol 2. THE GOLDEN TORC
Del Rey 1983
PB 483 pgs
ISBN 0-345-30838-7

Vol 3. THE NONBORN KING
Del Rey 1984
PB 429 pgs
ISBN 0-345-31421-2

Vol 4. THE ADVERSARY
Del Rey
PB 472 pp
ISBN 0-345-31422-0

Disillusioned and misfit humans from Earth's future, use a government
sanctioned one-way time machine to be transported back to Earth's Pliocene
Epoch, in an effort to live a more tranquil and individualistic life. Little
do they realize, that their arrival in this chosen time frame has been
preceded by the arrival of a group of humanoid aliens, who themselves have
escaped from their own untenable situation and who greedily greet the new
human arrivals; seeds for their own needs.

This is a richly textured, highly detailed and marvelously told series
(actually, from what I understand, a subset of a larger whole), with
elements of both SF and fantasy blended together. Colourful characters
abound and black humour runs amok. My only possible complaint, weak as it
may be, is that the story is TOO detailed; demanding constant attention and
defeating reading under distracting conditions.