Forensic geology is concerned with the application of geological information and techniques to problems that may come before a court of law. However, geology is often defined as the scientific study of the solid earth and is mainly concerned with rocks, minerals, sediments, fossils, and the processes responsible for their formation, whereas soil science is defined as the scientific study of soils which form in the uppermost layers of Earth's surface through modification of geological parent materials by a combination of physical, chemical, and biological processes. The concept of "dust" used by Locard is thus rather different from that generally employed in more specific geological contexts, where dust has been defined as "a suspension of solid particles in a gas, or a deposit formed of such particles" Airborne transport of the fine particles in suspension, prior to possible deposition, is an essential element of this definition.