Geology or Related Geological Terms +

An upward buildup of a surface by deposition of sediment: An aggradation is an expansion of land altitude caused by the accumulation of deposits or residue.

A naturally occurring fine-grained white or light-colored translucent form of gypsum: Alabaster is is often streaked or mottled (spotted or blotched with different shades or colors).

A soft material which is easily carved but seldom used for outdoor sculpture.

One of the aquatic protistan organisms that include many lime-secreting kinds: The seaweed is considered to be an alga in the its size varies from one cell to huge kelps.

Pertaining to algae: Algal limestones and reefs are largely formed by algae.

There are alga structures, generally laminated crusts called ooids, and pisoids, some of which may be inorganic.

Pertaining to precambrian granite of the Canadian Shield region: The Algoman age dates back to the post-Timiskamingian time and is classified as Archean.

Late Proterozoic: Algonkian is the main division of late Precambrian time and rocks (equivalent to Proterozoic).

Referring to material that is formed or introduced from somewhere other than the place it is presently found: Allochthonous rocks are those whose primary constituents have not been formed in their natural or original places.

Allocthonous is the misspelling of allochthonous.

A type of coal arising from accumulations of plant debris moved from their place of growth and deposited elsewhere: In her book on geology, Jill learned that allochthonous coal originated from a mass of plant remains transported from the place where they grew to somewhere else.

A rock that was transported a great distance from its original deposition by some tectonic process: Allocthon is generally related to over thrusting, recumbent folding, or gravity sliding.

Allocthon is a large displaced body of rocks, such as a rock mass that has moved a considerable distance by thrust faulting.

Allocthon is the opposite of autocthon.

Pertaining to alluvium (relating to, consisting of, or formed by sediment deposited by flowing water): Examples of this term are alluvial cones, alluvial fans, which are deposited gravel and associated sediments, and alluvial plains.

Deposited gravel, silt, soil, or clay by flowing water while slowing down in a river bed, estuary, or flood plain: An alluvium is unconsolidated detrital deposits ranging from clay to gravel sizes, generally poorly sorted, typically fluviatile (river or stream) in origin.

Succession of sexually and asexually formed groups of offspring belonging to a given species of organisms; metagenesis: Examples of the alternation of generations are microspheric and megalospheric foraminifers, polyps, and medusa stages of some coelenterates (invertebrate lacking a backbone or spinal column), etc.

"Coelenterates" are radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms.

One of the primitive mammals of the order Amblypoda: An amblypod is a moderately large early Paleogene hoofed mammal with blunt, elephant-like feet, small brain case, and unspecialized teeth.

A variety of quartz, colored violet by the presence of small quantities of impurities, such as manganese or iron and used as a semiprecious stone: Amethysts are found chiefly in the Ural Mountains, India, the United States, Uruguay, and Brazil.

Extinct late Paleozoic or Mesozoic cephalopod distinguised mainly by the complexity of the suture pattern of the shell: The ammonite had a coiled divided shell.

The closest current relation is the pearly nautilus.