Quaternary

The Quaternary is a geological period whose significance in the novel shifts from a scientific classification to a challenge posed by visible evidence. As the travellers read the rocks and fossils beneath Iceland, the period anchors disputes about the limits of geological theory and the antiquity of humanity; the discovery of a preserved human body then turns those disputes into an unsettling question about life underground.

Geological Time Made Visible

The descent is narrated as a passage through geological formations. In a gallery of changing rock, Harry identifies the strata as belonging to a transition state and to Silurian formations, reading the walls as a record of the earth’s earlier history. Later, the fossil marks in the marbles seem to show a progression from trilobites toward more developed animal life. The geological sequence is therefore not merely background: it gives the travellers a visible scale against which they try to understand where they are and how far back in time their surroundings reach.

That interpretation is repeatedly tested against the travellers’ experience. Harry invokes scientific teaching to argue that a journey deep into the earth should be impossible: the expected increase in heat would make the interior uninhabitable. Professor Hardwigg rejects theory as a reason to stop. Later, Harry calculates that their depth is approaching the accepted extreme limit for the earth’s crust, and asks what temperature known laws would predict there. He nevertheless tries to take the facts as they come, rather than simply force them into a prior explanation. The Quaternary belongs to this larger tension between geological models and observations that seem to exceed them.

The Human-Antiquity Debate

The period’s human significance is introduced through the nineteenth-century controversy over the Moulin-Quignon jawbone. In 1863, workers found a human jaw fourteen feet below the surface near Abbeville, alongside stone hatchets and carved flints. The find drew intense attention from learned societies and geologists. Many accepted it as evidence of a human fossil from the Quaternary, while Elie de Beaumont disputed the age of the deposit and rejected the idea that humans had lived alongside Quaternary animals. Professor Hardwigg had supported the majority view.

The debate had widened by the time of the expedition. Other jawbones and human implements had been reported in deposits in France, Switzerland, and Belgium, strengthening the case for human existence in the Quaternary. Still more provocative finds from Tertiary deposits were interpreted as animal bones shaped by human hands. The narrative explains that these discoveries had pushed estimates of human antiquity back beyond one hundred thousand years and made humanity older than the mastodon in the geological sequence. These claims are presented as part of the period’s changing paleontological debate, not as a timeless or uncontested scientific conclusion.

A Body in the Underground Cemetery

Against this background, the travellers encounter a recognizable human skull in a vast plain of bones. Its skin is stretched and parchment-like, its teeth intact, and its hair abundant. The preserved body appears to belong to the Quaternary and lies among mastodon remains. The scene gives immediate, physical force to a controversy that had previously been argued through disputed fossils, strata, and scholarly authority.

Professor Hardwigg calls the remains a fossil human contemporary with the mastodons, but admits that he cannot explain how the person came to be there or how the covering strata entered the cavity. He proposes that convulsions in the earth’s crust may have produced fissures, landslides, and chasms that carried material into the underground space. The hatchets and carved flints beside the body support his identification of a human presence in the Stone Age, while the body’s preservation remains unexplained. He speculates that the person may have visited the centre of the earth as a pioneer of science, but this is a conjecture rather than an established account of the remains.

The Question Left Open

The discovery is not isolated: other bodies appear across the plain, intermingled with the remains of extinct animals. Their presence transforms the travellers’ interpretation of the underground world. The narrative leaves two possibilities in suspension: the dead may have been buried far below by a catastrophic upheaval, or people may once have lived in this subterranean setting, beneath its artificial sky, and experienced ordinary lives there. The travellers have previously seen living marine monsters and fish, but no living human inhabitants of the abyss. Thus the Quaternary functions both as a measure of deep human time and as the threshold of an unresolved question: whether the underground world preserves only the remains of an ancient catastrophe or evidence of a human world that once existed below.