For all he knew, these tunnels were infinite and ran from one magnetic pole to the other, filling the entire mantle like an enormous ant farm. All he knew for sure was that the two primary laws of aquatic physics still applied. Even in the absence of running water, he could use those rules to predict the course it had taken long ago. These tunnels might have been the result of arbitrary flow and chemical interactions with the acidic limestone, but they still demonstrated an element of predictability. He’d learned that for flowstone to form there had to be an orifice through which some quantity of fluid passed. Mere drops of condensation and the eternal patience of nature formed stalactites, stalagmites, and all of the various other speleothemic projections. Duan undoubtedly would have been able to lend deeper insight that would have saved Mitchell a number of false starts and wrong turns, but he tried not to think about the geologist’s fate for fear of losing his resolve, which was about the only thing keeping him going.
