Many bizarre, X-Files-worthy theories claim that the earth's center, rather than being a blazing chunk of molten ore, is actually hollow and populated by gnome-like necromancers and mystic elves. Fort Collins power trio Core of the Earth (playing Friday, August 13, at the 15th Street Tavern) sounds like it could go either way on its debut full-length, Loadstone. On one hand, the disc's lava flow of sludgy tempos and iron-alloyed guitar is straight out of the smelting pot of stoner rock, a viscous and vitriolic compound of the Melvins, Saint Vitus and vintage Black Sabbath. And yet the ethereal drone of songs like "Grimaldi (The Cycle of Transformation)" and "It Came From Gongüttar" hint at a serious obsession with the mythologies of both ancient Scandinavia and the movie Heavy Metal. Lodged somewhere between rock-and-roll fantasy and technical ecstasy, Loadstone points the way toward the hidden essence of hard rock, punk and the subterranean grinding of science against magic. The truth is in there.