A forensic geologist is an earth scientist who uses soil and mineral analysis to provide legal evidence. The field dates to the early 20th century, when Georg Popp pioneered techniques of using the microscopic characteristics of soil samples to tie a suspect to a crime scene.
The individual minerals and compounds present in soil and rocks can serve as a sort of geologic fingerprint, identifying the source of the material. By comparing an unknown sample with a sample taken from a target area, a forensic geologist may be able to prove that a subject was at a given location. In concert with traditional forensic evidence, this can prove to be a vital link in the chain that ties a suspect to a crime.
Forensic geologists also find work in civil cases. For instance, contaminants released into an aquifer may be traced back to their source by tracing water flow and dispersion patterns. Petroleum leaks can be effectively age dated, helping identify who was responsible for an environmental spill by pinpointing when it occurred. Geologists can also study industrial disasters like mine or road collapses to determine if improper construction or excavation techniques may have been responsible for the failure, or if the accident occurred due to natural causes.