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.

Hardpan (Caliche) “Hardpan” is a highly dense and solid layer of soil near the ground surface, which is usually comprised of clay or silty-clay soils. Hardpan forms by cementation over time, during the process of precipitation of insoluble substances such as calcium carbonates, silica, iron oxides, and other organic matter. “Hardpan” is a term mostly…

Transgression Transgression: In geology, the term transgression is the formation of a specific sequence of sedimentary and metamorphic layers, that are the result of ocean water advancing onto land. To illustrate, when transgression occurs over millions of years, geologists find a layer of sand, overlain by shale, and overlain again by limestone. The opposite of…

Runoff (R) The term “Runoff” (R) in hydrogeology and geology refers to the part of rainfall which accumulates on the ground surface and naturally forms into flowing streams.

Perforated Horizontal Pipe in Methane Mitigation Perforated Horizontal Pipe: As per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a perforated horizontal pipe is a PVC or ABS pipe that contains a series of small holes or narrow openings placed equidistantly along the length of the pipe, and is…

Mineral Assemblages Mineral Assemblages: In the field of geology and the branch of mineralogy, the term “mineral assembles” means the minerals that compose a rock, including the different kinds and their relative abundance.