rock electrical conductivity
41rare-earth element — /rair errth /, Chem. any of a group of closely related metallic elements, comprising the lanthanides, scandium, and yttrium, that are chemically similar by virtue of having the same number of valence electrons. Also called rare earth metal. [1955 …
42Ganymede (moon) — Ganymede Image of Ganymede s anti Jovian hemisphere taken by the Galileo probe. Lighter surfaces, such as in recent impacts, grooved terrain and the whitish north polar cap at upper right, are enriched in water ice. Discovery …
43Ground-penetrating radar — (GPR) is a geophysical method that uses radar pulses to image the subsurface. This non destructive method uses electromagnetic radiation in the microwave band (UHF/VHF frequencies) of the radio spectrum, and detects the reflected signals from… …
44archaeology — archaeologist, n. /ahr kee ol euh jee/, n. 1. the scientific study of historic or prehistoric peoples and their cultures by analysis of their artifacts, inscriptions, monuments, and other such remains, esp. those that have been excavated. 2. Rare …
45mining — /muy ning/, n. 1. the act, process, or industry of extracting ores, coal, etc., from mines. 2. the laying of explosive mines. [1250 1300; ME: undermining (walls in an attack); see MINE2, ING1] * * * I Excavation of materials from the Earth s… …
46Phosphorus — This article is about the chemical element. For other uses, see Phosphorus (disambiguation). silicon ← phosphorus → sulfur …
47Mountaintop removal mining — Mountaintop removal site Mountaintop removal in Martin County, Kentucky M …
48Near-surface geophysics — is the use of geophysical methods to investigate small scale features in the shallow (tens of meters) subsurface. It is closely related to applied geophysics or exploration geophysics. Methods used include seismic refraction and reflection,… …
49Honey — For other uses, see Honey (disambiguation). Jars of honey and honeycomb …
50Nikola Tesla — Tesla, aged 37, 1893, photo by Sar …
