Subterranean lands occur repeatedly throughout the Oz literature.
L. Frank Baum, Ruth Plumly Thompson, and later writers on Oz had a range of precedents and models for creating exotic locations under the earth. Two of the most famous works of this type are Lewis Carroll's Alice's Adventures in Wonderland (1865) and Jules Verne's Journey to the Center of the Earth (1864), though there were various others too; John Uri Lloyd's Etidorhpa (1895), for one example, was very famous in its own era but is less well known today.
In addition to purely fictional works, there were others that pretended to factuality, in a genre that today might be called speculative pseudoscience. These books presented a theory that the Earth is a hollow sphere, and its concave interior surface holds landscapes, countries, even continents and oceans, all lit by a central inner sun. John Cleves Symmes, Jr. was the most famous of several nineteenth-century theorists who propounded hollow-Earth ideas — though the general concept can be traced further back through the intellectual history of humanity.
These works, overtly fictional or otherwise, address ideas that include sources of light and gravitational fields. (The hollow-Earth advocates often give the outer and inner spheres of the Earth there own separate fields of gravity, with a zone of equilibrium, a balancing-point, between them.)
Baum seems to have been influenced by the hollow-Earth literature at one particular point, when he sends Dorothy Gale's party underground at the start of Dorothy and the Wizard in Oz. Via earthquake, they pass into a vast interior space, lit by "six great glowing balls suspended in the air." The largest is white and sunlike. Dorothy and company fall more slowly (like Alice entering Wonderland) until they touch down gently in a landscape comparable to those of the outside world, and then proceed on an adventure through a series of subterranean countries. From the Land of the Mangaboos they pass through the Black Pit to the Valley of Voe, Pyramid Mountain, and the Land of Naught.
Baum's other major subterranean domain is the Nome Kingdom, which he introduces in Ozma of Oz and employs in subsequent books (notably Tik-Tok of Oz). The Nome Kingdom is in general the spelunker's world of caves, caverns, and tunnels, though it has some interest offshoots as well, like the Metal Forest.
John Dough and his companions visit the underground Kingdom of the Fairy Beavers in John Dough and the Cherub. Twinkle and Chubbins visit a gleaming white city inside "Sugar-Loaf Mountain." Trot and Cap'n Bill pass through a cave and a tunnel at the start of The Scarecrow of Oz.
Thompson presents a number of subterranean lands in her books, starting with her first and continuing to one of her last. Yet since her underground realms tend to have their own skies and suns and moons, it is not always clear what is underground and what is not.
Down Town, in The Hungry Tiger of Oz, is certainly subterranean, though it has its own sky and sun. The title character is not surprised to find the sun shining underground: as the Hungry Tiger says, "Doesn't the sun go down every day?" Down Town's night is lit by a moon that is green and square, a detail that Thompson does not elucidate.
In her first book, The Royal Book of Oz, the Scarecrow falls through the Earth to the Silver Island, another place that has its own sky and sun; is it underground, or has the Scarecrow fallen all the way through the Earth to an alternative China on the other side? Benny the Public Benefactor similarly falls through the Earth in The Giant Horse of Oz, and reaches Oz — but this does not mean that Oz is underground. In the same book, Benny, Trot, and the Scarecrow have a sojourn in caves of the Ozure Isles that are unambiguously subterranean.
Blankenburg, in The Lost King of Oz, is another ambiguous case. To get there, Snip falls down a well, but then travels sideways and up again through another well, so that Blankenburg could be...who knows where.
Torpedo Town and the Delves are found in The Purple Prince of Oz. The protagonists in Handy Mandy in Oz penetrate the domain under the Silver Mountain. Wumbo the Wonder Worker lives in a cave in The Gnome King of Oz. There is an enchanted cavern in Jack Pumpkinhead of Oz.
- Crooked pillars of irregular rock held up the blue stone sky.... Radium stars in the sky sent out a misty phosphorescent glow. From the square, arched passageways branched out in every direction, not unlike the subways at home, except that they were much higher and lighter, beautifully tiled, and decorated with precious stones.
Subterranea has is own paradoxical weather — showers of sunshine called "subter-rain."
While there, Speedy learns that Subterranea is the lowest of nine layers of underground realms:
- Farther Down
The ninefold scheme may ultimately derive from Dante's Inferno.
Other Royal Historians
Jack Snow does not create a true subterranean land in either of his Oz books, though he comes close in The Magical Mimics in Oz. His Magical Mimics live within the hollow Mount Illuso; and Dorothy and the Wizard are imprisoned in a dungeon in its depths. A second visit to the Fairy Beaver Kingdom occurs in The Shaggy Man of Oz.
As its title indicates, Marcus Mebes' The Mysterious Caverns of Oz also belongs in the subterranean category.
- Alberto Manguel and Gianni Guadalupi. The Dictionary of Imaginary Places. New York, Harcourt Brace Jovanovich, 1987.