Cation Cation: In the fields of chemistry and geochemistry, a cation is a positively charged ion. The oppositely charged ion is an anion.

Thermosphere Thermosphere: The thermosphere of a terrestrial planet is the fourth and final member of the atmosphere. On Earth, the thermosphere starts atop the mesosphere at approximately 85 kilometers above mean sea level. The upper limit of the thermosphere is reasonably presumed to terminate approximately 95 kilometers above mean sea level. In fact, most of…

Seiche Definition The term “Seiche” in geology refers to a wave-oscillation, that comes from any surface body of water, that is initiated by an earthquake or changes in atmospheric pressure. For instance, the rippling waters of a lake or at the bay of an ocean.

Unconfined Aquifer Unconfined Aquifer: In the hydrogeology branch of geology, an unconfined aquifer is an aquifer that has a water table. In fact, an unconfined aquifer can only be the uppermost hydrogeologic unit and is particularly one that has no hydraulic head (or pressure) that is equal to atmospheric pressure. To illustrate, depth to groundwater…

Liquid Limit (LL) “Liquid Limit (LL)” in the field of geological engineering, refers to the upper limit of the “plastic state.” This is a separation of the plastic phase and viscous liquid phase when measuring soil consistency. Mathematically, it is the water content (basing on the percent of dry weight), at which two sections of…

Trench Dam Trench Dam: Per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a trench dam is part of a methane mitigation system. A trench dam is essentially a subsurface barrier that exists within a furrow or ditch, that is adjacent to the foundation of a building in a…