www.starironworks.com 257 Caroline Street Punxsutawney, PA 15767 800-927-0560 • 814-427-2555 Fax: 814-427-5164 SERVINGTHECONSTRUCTION INDUSTRY Serving the Drilling Industry 36 NOVEMBER 2020 WorldWide Drilling Resource ® Frequently-Used Geological Terms Part 91 Glossary Adapted from the Dictionary of Geological Terms S Seismic Stratigraphy - The study of stratigraphy and depositional facies as interpreted from seismic data. Seismic Surveying - The gathering of seismic data from an area; the initial phase of seismic prospecting. Seismogram - The record made by a seismograph. Seismograph - An instrument used to record seismic waves. Seismologist - A person who applies the methods or principles of seismology, such as earthquake prediction or seismic exploration. Seismology - The study of earthquakes, and the structure of the earth, by both natural and artificially generated seismic waves. Selective Fusion - The fusion of only a portion of a mixture such as a rock. The liquid portion will generally contain a larger proportion of the more fusible components than the parent material had. Selenite - The clear, colorless variety of gypsum, occurring in distinct transparent monoclinic crystals or in large crystalline masses which easily cleave into broad folia. Selenology - A branch of astronomy which deals with the moon and the science of the moon, including its geology. Selenomorphology - Geomorphology of the moon and the study of lunar land- forms as well as their origin, evolution, and distribu- tion. Self-potential Method - An electrical exploration method in which the spontaneous electrical poten- tials caused by electrochemical reactions associated with clay or metallic mineral deposits are deter- mined. Selvage - The altered clayey material found along a fault zone. Also refers to a marginal zone of a rock mass, having some distinctive feature of fabric or composition, specifically the chilled border of a dike which commonly shows a finer grain and sometimes a glassy texture. More terms next month! DIR WWDR photo of Selenite from Washoe County, Nevada. Horizontal directional drilling projects use seismographs to monitor for changes in sensitive locations.