Jules Verne intended his Journey to the Centre of the Earth to be not only thrilling but also didactic; he wanted to share the exciting new developments in various scientific fields with his readers and give them more in-depth knowledge than they might normally expect from a novel. Thus, modern readers should keep in mind a few of the geological aspects that the novel covers and that supplement Verne’s narrative.
1. The structure of the Earth: the Earth is divided into a crust, mantle, and core. The crust is hard but thin, about five miles under the oceans and twenty under the continents. The mantle, which is divided into an upper and lower part, is about 1,800 miles thick and is comprised of hot, semisolid rock. The core is also divided; the outer core is comprised of liquid (iron and nickel) and is about 1,800-3,200 miles below the surface and 1,400 miles thick, while the inner core is solid nickel and iron, extremely hot, and 3,200-3,960 miles below the crust and 750 miles in diameter. According to a recent article from Live Science, "The reality of exploring under Earth's surface isn't so simple, says Damon Teagle, professor of geochemistry at the National Oceanography Center, University of Southampton. Teagle has worked on eight drilling projects worldwide, all of which have extended just miles into the Earth's uppermost layer, the crust. Those holes might sound deep, but they're nowhere near getting to the Earth's center, some 3,951 (on average) miles below the surface."
2. Mastodons: These massive creatures roamed a terrain primarily in North America about 3.75 million to 11,000 years ago (the Pleistocene era). They are part of the Proboscides order (like elephants and mammoths), were about 8-10 feet tall at the shoulder, and weighed between 4 and 6 tons. Their blunt, grinding teeth were used to chew plants and herbs. Both males and females had upper tusks, while only males had short lower tusks. Their bodies were long, their legs comparatively short, and they were covered in long, reddish-brown fur.
3. Ichthyosaurus: Its name, which means “fish lizard,” is apt given its long, sinuous body and eel-like movements. These creatures are often grouped with dinosaurs but were part of a separate group of marine vertebrates. First appearing in the Triassic era, they became most numerous in the Jurassic era. The last appeared during the Cretaceous period. Ichthyosaurs did not leave the water to lay eggs; rather, they gave birth to live young. They breathed air and lacked gills, to some extend resembling the whales of today.
4. Plesiosaur: This creature was not a dinosaur but a prehistoric marine reptile. It was characterized by a long neck, four flippers resembling paddles, and a tail. Plesiosaur teeth were like needles and curved around its U-shaped jaw, its nostrils were closer to its eyes than to its snout, and its hearing capabilities were similar to those of whales and dolphins. These animals were each about 12 feet long, weighed 900 pounds, and could reach speeds of 10 mph. A creature that gave birth to live offspring, the Plesiosaur had a long neck that made it look like a swimming brachiosaurus.
5. Etna: This mountain, located on the island of Sicily above the town of Catania, is the largest active volcano in Europe and has the longest period of documented eruptions of any volcano worldwide. Its maximum elevation is 10,925 feet. Etna has been growing for over 500,000 years and is currently in an ongoing series of eruptions. (The first eruptions were recorded in 1500 BC and its most powerful was in 1669.) The UNESCO world heritage website says, "The almost continuous eruptive activity of Mount Etna continues to influence volcanology, geophysics and other Earth science disciplines. The volcano also supports important terrestrial ecosystems including endemic flora and fauna and its activity makes it a natural laboratory for the study of ecological and biological processes. The diverse and accessible range of volcanic features such as summit craters, cinder cones, lava flows and the Valle de Bove depression have made the site a prime destination for research and education.”