Plotting values indicative of characteristics of an underground formation. At least some of the illustrative embodiments include: obtaining a plurality of values indicative of characteristics of an underground formation; and plotting the plurality of values on an output device of a computer system. The plotting may further include: plotting parallel to a first axis a first plurality of symbols where each symbol is indicative of a value of a characteristic of a first portion of the underground formation, location of the first plurality of symbols with respect to the first axis is indicative of a first parameter, and location of the first plurality of symbols with respect to a second axis is indicative of a second parameter distinct from the first parameter; and wherein location of at least one symbol with respect to the first axis is also indicative of a third parameter, different than the first and second parameters.