Spatter cones, [104].
Speculative philosophy vs. observational geology, [5].
Spencer, J. W., cited, [260], [344], [350], [353], [366].
Spethmann, H., cited, [267].
Sphalerite, [453].
Spherulites, [33].
Spherulitic texture, of igneous rocks, [33].
Sphinx, erosion by natural sand blast, [205].
Spits, [240].
Spitzbergen, [154].