Thanks JT and Atpollard. Atpollard, to answer your questions in reverse order: no, I haven't discussed this method in any of my tutorials. The hewn-stone-inlay effect was really just a matter of applying a low opacity (35%) pattern overlay (a sort of gravel pattern) to the polar projections and other text and symbols, and then adding several applications of Bevel & Emboss (Inner Bevel, Direction Down), each at different sizes. Then I just turned the original polar projection layer as well as the text and symbol layers invisible and voila. Nothing to technical.

Cheers,
-Arsheesh