A geological engineer is an engineer who specializes in the field of geological engineering; that is, the application of engineering science and technology to the study of geological materials as part of the engineering design of such things as mines, minerals and mineral products. After traveling back to 1893 San Francisco Earth, Lieutenant Commander Data visited an assayer named Ches Whitley. During his visit, Data claimed to be a geological engineer who was interested in locating information about mining operations during the 1850s. (TNG: "Time's Arrow, Part II" )