Twinning Definition
Twinning is the observed intergrowth of multiple crystals in a symmetrical fashion. This term applies to the examination of rock thin sections, in the field of optical mineralogy.
Twinning is the observed intergrowth of multiple crystals in a symmetrical fashion. This term applies to the examination of rock thin sections, in the field of optical mineralogy.

Maximum Soil Screening Levels (MSLs) Maximum Soil Screening Levels (MSLs): MSLs are a list of risk-based hydrocarbon concentrations for soil pollution evaluations, that is developed by the California Regional Water Quality Control Board. These screening levels are based on the Leaking Underground Fuel Tanks (LUFT) Manual, for cleaning up soil contamination from leaking USTs. However, MSLs…

Topple Definition Topple – Slope movement due to forces that cause an overturning moment about a pivot point below the center of gravity of the unit.

Well Log (Boring Log) Well Log: A geological well log (or boring log) is a detailed record of subsurface materials encountered during a drilling project. Boring logs, or well logs, are written by a geologist, and describe the physical subsurface characteristics and lithological units encountered during well-plotting. Well logs include information about depth, different formations,…

Ultramafic Definition In the study of geology, the term “ultramafic” refers to an igneous rock that comprises up to 90% mafic minerals, or more.

Seismology Seismology: (seis·mol·o·gy) a branch of geology and geophysics that relates to earthquakes, including but not limited to their causes, effects, hazards, and mitigation techniques. Seismologists at the United States Geological Survey (USGS) use cutting-edge technology to measure seismic wave properties and geological hazards that trigger them or are triggered by them. In turn, seismology…

Dip-Slip Fault Dip-Slip Fault: In geology, a dip-slip fault is any fault in which the earth’s movement is parallel with the dip of the fault plane. For example, a normal fault, reverse fault, or listric fault. The opposite of a dip-slip fault is a strike-slip fault.