Tertiary Period (183ed163)

The Tertiary Period gives the explorers a tangible encounter with deep geological time. In the underground world, ancient strata yield fossils and a vast forest of vanished plant forms; the distant past is not merely reconstructed from fragments but appears to unfold around them, culminating in the narrator’s vision of the Tertiary and Quaternary eras brought back to life.

Geological Time Made Visible

As the travelers move through changing rock, the narrator reads the formations as a sequence of geological ages. He identifies a transition into Silurian stone, then sees the rocks advance toward the Devonian: marble bears fossil marks, and the remains include fish associated with an early stage in the development of reptile life. To him, the progression through strata is also a progression through animal history, though Professor Hardwigg presses onward despite the warning the narrator sees in that ascending scale.

The period’s significance is therefore both scientific and dramatic. Geological classification, which could seem abstract in a textbook, becomes a route through the earth. Each change in stone offers evidence of a different world and lets the travelers imagine history not as a human measure of time, but as an immense succession of forms and environments.

The Forest of the Tertiary

After leaving the fossil-rich passages, the travelers reach a forest the narrator identifies as vegetation of the Tertiary Period. Its luxuriant growth includes enormous palms of an unknown species, fossil palms, pines, yews, cypresses, and conifers, all tangled together by creeping plants. Mosses and ferns carpet the ground, while brooks run beneath the trees. The assemblage disregards the familiar geography of the surface: oak stands beside palm, eucalyptus leans against Norwegian pine, and northern poplar mingles with New Zealand kauris.

This abundance is strikingly incomplete. The plants have grown without sunlight’s vivifying warmth, and the whole forest has lost its colors: leaves lack green, while numerous flowers are pale and scentless, like paper faded by exposure. The forest is at once vigorous and lifeless in appearance, a preserved abundance whose strangeness makes the underground environment feel like another world rather than a simple survival of the past.

From Fossil Evidence to Living Prehistory

The period’s meaning is sharpened by the explorers’ earlier encounters with fossils and contemporary paleontological arguments. Their passage through strata containing traces of ancient animals supplies a material prelude to the forest. Above ground, discoveries such as the human jawbone found at Moulin-Quignon had intensified debate over how far human antiquity extended; the narrator recounts arguments about whether people lived during the Quaternary and whether evidence from still older deposits could place human activity in the Tertiary. These controversies frame the underground discoveries as challenges to accepted timescales, not as settled modern conclusions.

In the forest, the distinction between geological record and living scene collapses. The narrator imagines immense elephants tearing down branches and uprooting trees, then recognizes the vision as the realization of a dream in which the Tertiary and Quaternary periods passed before him. The passage turns the scientific idea of deep time into an overwhelming spectacle: the travelers are isolated far below the surface, exposed to the possibility that the ancient world is not only visible but inhabited.