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The first of three eras of the Phanerozoic Eon, lasting from about 570 to 240 million years ago.


A tract of land or real property owned by individuals, a group of people, organizations, the government, etc.


A general term for a small, rounded, water-worn stone; specifically, a rock fragment larger than sand and smaller than a cobble, having a diameter in the range of 0.16 inches to 2.5 inches (4 millimeters to 64 millimeters).


An ultramafic, intrusive, igneous rock composed primarily of olivine and pyroxene.


A geologic time unit intermediate in rank between an Era and an Epoch, e.g. Ordovician Period.


How quickly water moves through soil and the ability of water to be held for plant use.

Pore Water

Subsurface water in the voids of rock, sediment, or soil.


The amount of empty space between soil particles.


That eon of geologic time represented by rocks in which there is little evidence of life (fossils), comprising three eras: Early, Middle, Late – from about 2,500 million to 570 million years ago.


A common, pale-bronze or brass yellow, cubic-shaped mineral composed of iron and sulfur; also, commonly referred to as “fool’s gold.”


A group of dark silicate minerals with varying amounts of Ca, Fe, Na, and Mg, typically found in mafic and ultramafic rocks.