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

Effective Size (D10) “Effective Size” (D10) is an engineering geology term. Effective Size represents a diameter that directly corresponds to the percentage, by weight, of grains that equal to 10% on the grain-size diagram. To illustrate, 10% of the soil sample particles are finer-grained, and 90% of the sample particles are coarser than the “effective…

Porosity (n) “Porosity” (n), in the geological engineering field, is a percentage value that represents the bulk volume of a rock or soil, that is occupied by the void space within. Porosity (n) Formula Porosity (n) = [(Volume of Voids ÷ Total Volume) x 100%]

What is a Concrete Arch Dam? A Concrete Arch Dam is a curved freshwater-retaining structure that is concave in the hydro-geologically down-gradient direction, and uniformly thick from the base to top. With Concrete Arch Dams, a major part of the water load value gets distributed to the abutments of the dam. Thus, Concrete Arch Dams…

Lumber Moisture Content Grade Lumber moisture grading is a manufacturer-provided value of moisture content, for consumers and contractors to use. There are five (5) lumber moisture content designations (S-GRN, S-DRY, KD, MC 15, and HT). Lumber Moisture Grading Lumber grade “S-GRN” stands for “surface green,” which means it is not dry, and has a moisture…

Troposphere Troposphere: The troposphere of a terrestrial planet is the lowest member of the atmosphere. On Earth, the troposphere starts atop the ground surface and terminates roughly 10 kilometers above mean sea level. In fact, geologists understand that most of the Earth’s water vapor (clouds) exists in the troposphere. And the next member of the…