Despite the title, the book covers very little specifically on geology.  It works through stress, strain, and other tensor quantities, but assumes you know little about the math.  Fully worked problems make up the bulk of the book following a few introcutory chapters.  I've found it a nice review of the math, but haven't fully explored the solution sections.  I got the book from Cabot Science Library here at Harvard. I wouldn't recommend buying it on amazon it's not worth the $72, but it is a nice addition to Timoshenko's theory of elasticity.