Surface-Wave Magnitude “Surface-Wave Magnitude” is the magnitude of an earthquake that scientists estimate using measurements of the amplitude of surface waves.

Body-Wave Magnitude Body-Wave Magnitude: A method for determining earthquake size from the amplitude of body waves. The body-wave magnitude focuses on P-waves and S-waves, which travel faster through the Earth’s crust and mantle.

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.

“Test” Definition in Paleontology In the field of paleontology, a subsidiary of geology, the term “test” refers to the external hard part of an invertebrate.

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,…

Thrust Fault Thrust Fault: In the field of geology, a thrust fault is a reverse fault in which the fault plane dipping angle is less than 45 degrees. Thrust faults are dip-slip faults, and can also be listric faults. For instance, the fault underlying the western embankment of the historical St. Francis Dam in Saugus,…