Devonian

The Devonian is a geological period invoked during the explorers’ descent to interpret the rocks and fossil life around them. In the narrative, its strata preserve traces of ancient marine animals, and the identification of a living fish as belonging to a family known only from Devonian fossils makes geological time feel less remote: the past appears not only in stone but in a creature held before the travelers.

Strata and the Descent

As the travelers move through the underground gallery, the rock changes from shining lava to formations Henry identifies with an earlier geological state. He describes the transition into Silurian stones and reads the surrounding schists and calcareous rocks as sediment deposited by waters that once covered the Earth. The strata are thus not merely a route through the subterranean passage; they become evidence through which the expedition tries to reconstruct the planet’s history.

Further along, the gallery’s direction is uncertain, and the rocks retain their transitional character even when the path seems to descend. Under the electric light, the walls display calcareous rock, old red sandstone, and variegated marbles. Their surfaces bear marks of primitive animals. Henry sees a progression from rudimentary trilobites toward more developed forms, including fish that suggest an early stage in the development of reptilian life.

Fossils and Geological Time

The Devonian seas, Henry explains, supported large numbers of these fish, whose remains were deposited in immense quantities in newly formed rocks. He reads the fossils as part of an ascending scale of animal life, with humanity at its summit. The observation gives the descent a chronological dimension: the travelers seem to pass through successive records of ancient life, even as the geological evidence does not always confirm Henry’s interpretation of their direction.

The period also belongs to a wider nineteenth-century debate about how far back human existence could be placed. The narrative recalls the Moulin-Quignon jawbone, discovered in 1863 fourteen feet below ground near Abbeville alongside stone tools. Scientists disputed the age of the deposit and whether humans had lived alongside Quaternary animals; further finds and objects attributed to human workmanship in older, Tertiary deposits intensified arguments about humanity’s antiquity. Against this debate, Devonian strata mark a much earlier world of fossil marine life, not evidence that humans lived in that period.

The Living Fish

The Devonian becomes consequential to the expedition when the Professor examines a captured fish. Its flat head, rounded body, bony scales, toothless mouth, enlarged pectoral fins, and near-absence of a tail make it unlike familiar living species. After studying it carefully, the Professor identifies it as belonging to a family extinct for ages and otherwise known only through fossil remains in Devonian strata.

That identification changes the meaning of the fossils the travelers have been reading. The fish is not merely a resemblance to an ancient form: in the Professor’s account, it is a living specimen of a lineage represented elsewhere only by fossils. Henry’s astonishment gives the discovery its force, while the Professor treats the chance to examine such an animal as a naturalist’s extraordinary privilege.

Narrative Significance

The period links the physical route underground to the deep chronology reconstructed by geology. Fossil impressions make distant eras legible in the gallery walls, while the live fish unsettles the usual boundary between the extinct past and the present. The episode stages scientific knowledge as both disciplined classification and direct encounter: the Professor tests Henry’s initial opinion by inspecting the animal’s features, then uses its anatomy and fossil record to identify it.

The human-remains discussion broadens that encounter into a question of scale. The narrative presents contemporary disagreement over the age of human fossils and the implications of artifacts found in older deposits, while distinguishing those claims from the Devonian’s fossil fish. Geological time is therefore not a single settled ladder but a field of evidence and argument, made immediate by the travelers’ passage through strata and by an animal that appears to have crossed the boundary between fossil record and living world.