Revisiting Geological Eras

Poul Anderson treats us to:

the Psychotechnic Institute;

the Polesotechnic League;

Technic civilization;

the inappropriately entitled The Psychotechnic League;

the Paleotechnic geological era (mass extinction)!

The Paleotechnic must have been preceded by the Neotechnic?

Anderson's Time Patrolmen visit, e.g., the Pleistocene and the Pleiocene, and other time travelers visit elsewhen, but none of them share with us any detailed information about future Epochs, Eons, Eras or Periods so it is the nodes of the galactic brain in Genesis who inform us of the Paleotechnic.

In the period of Wayfarer and Kalava, there is an Arctican continent with geographical features known only to Gaia:

the Coast Range;
the Remnant River;
the Bountiful Valley;
the Boreal Mountains (with naked rock peaks);
the Rainbowl Lake;
the forested Mount Mindhome, hiding Gaia's physical centrum in clouds.

The centrum: dome, towers, silver spiderwebs, mobile units, darting and hovering flyers, shimmering air, force fields, quantum waves, microscopic and submicroscopic entities. (Kalava knows "'...old tales of monstrous things glimpsed from afar.'" (Genesis, p. 115))

Approaching from space, Wayfarer gets a god's eye glimpse of territory that we have already seen from a human point of view:

the mainly green fringe of a large continent stretching east-west;
"...a stretch of sea..." with maybe "...something peculiar on it..." (p. 128);
the circumpolar landmass;
a globe entirely unlike the one Brannock remembers.

Plate tectonics have slowed. Radioactivity and core heat have declined. But geological processes continue. Arctica broke free (from where?), drifted north, collided with other land and lifted the Boreals. Gaia and Brannock remember the Earth that was.