WorldWide Drilling Resource

Frequently-Used Geological Terms Part 77 Glossary Adapted from the Dictionary of Geological Terms R ~ Radiometric Dating - Calculating an age in years for geologic materials by measuring the pres- ence of a short-life radioactive element, like carbon-14, or a long-life radioactive element plus its decay product, such as potassium-40/argon-40. The term applies to all methods of age determina- tion based on nuclear decay of natu- rally occurring radioactive isotopes. Raise - A mine shaft driven upward from a lower to a higher level. Rank - The degree of metamorphism in coal. It is the basis of coal classifi- cation into a natural series from lig- nite to anthracite. Rapakivi Texture - A texture original ly described from Finnish granites. In typical specimens, flesh-colored potassic feldspar occurs as rounded crystals a few centimeters in diameter which are mantled with sodic plagioclase (feldspars dominant in sodium). Rare Earths - Oxides of a series of 15 metallic elements, from lanthanum to lutetium; as well as three other elements, yttrium, thorium, and scandium. These elements are not especially rare in the earth’s crust, but concentrations are. The rare earths are constituents of certain minerals. Often abbreviated REO. Rayleigh Wave - A type of surface wave having a retro- grade, elliptical motion at the free surface. Raypath - The imaginary line along which wave energy trav- els. A raypath is always perpendicular to the wave front in isotropic media. Reaction Line - In a ternary system, a boundary line along which one of the two crystalline phases reacts with the liquid, as the temperature is decreased, to form the other crystalline phase. Reaction Pair - Any two minerals, one of which is formed at the expense of the other by reaction with liquid; any two adja- cent minerals in a reaction series. 46 JANUARY 2019 WorldWide Drilling Resource ® upgrading 20 valves along the project’s route. Replacing part of one pipeline seg- ment required boring below the Harbor Freeway. Construction crews used hori- zontal directional drilling (HDD) to create a small tunnel below the busy freeway to reduce environmental impacts, as well as enhance public safety and energy reliability. “Our natural gas system pipelines are the arteries that keep affordable and clean energy flowing to homes, businesses, hospitals, schools, power plants, and other critical facilities throughout Southern California,” said Rick Phillips, senior director of SoCalGas’ Pipeline Safety Enhancement Plan. “SoCalGas is committed to modernizing our natural gas system so that we can continue to provide every Southern Californian with the affordable and reliable energy they deserve.” The pipeline replacement project is part of SoCalGas’ Pipeline Safety Enhancement Plan, a multibillion dollar pro- gram which tests and updates the natural gas pipeline infra- structure in Southern California. Since the program began in 2013, SoCalGas has conducted hydrostatic pressure tests on 94 miles of pipeline, installed 89 miles of new pipe, and installed or upgraded 152 valves to be automatically or remotely controlled throughout its service territory. The com- pany’s investments help deliver reliable energy while keep- ing bills affordable for customers. Ralph L. Franklin, Councilman for City of Inglewood said, “Thank you, SoCalGas, for the investment that you made in the Inglewood community and for your efforts to provide your customers with a safe and reliable product and service. Your commitment to keep City Officials and City Staff members updated on the project’s progress, along with your efforts to proactively address the concerns of Inglewood residents insured a relatively smooth project with very little inconvenience and/or disruption. This was a job well done and conducted with great professionalism.” California Natural cont’d from page 32. MIN Rapakivi is Finnish for crumbly rock, because the different heat expansion coefficients of the com- ponent minerals make exposed rapakivi crumbly.