Glossary


collision zone

a collision zone is the zone or belt where two pieces of continental crust have collided after closure of an intervening ocean.

 

conglomerate

coarse grained clastic sedimentary rock, composed of more or less rounded fragments or particles at least 2mm in diameter (granules, pebbles, cobbles, boulders), set in a fine-textured matrix of sand or silt, and commonly cemented by calcium carbonate, silica, iron oxide, or hardened clay.

 

continental blocks

separate or geologically unique blocks or rock masses that together form the continent - these would have formed independently of one another, having different geological histories and ages.

 

craton

a part of the continental crust that has been stable for at least 1000 million years. Cratons are typically formed of Lower to Middle Precambrian igneous and metamorphic rocks with a subdued surface relief which in places are overlain by largely undeformed Upper Precambrian or younger sedimentary rocks.

 

Cretaceous

the interval of geological time that began about 140 million years ago, and lasted about 75 million years. It is the final period of the Mesozoic era, and precedes the Tertiary Period.

 

crustaceans

any arthropod of the subphylum Crustacea, characterized chiefly by two pairs of antenna-like appendages in front of the mouth and three behind it. Present groups are represented by shrimp, crabs, lobsters, copepods and isopods; most forms are marine.

 

deformed

having undergone deformation - the alteration, such as faulting, folding, shearing, compression and extension of rock formations by tectonic forces.

 

desertification

is the slow expansion of the world's deserts, either due to gradual climate change, and also nowadays due in part to rain falling in the desert margins, and the land being heavily farmed and overgrazed, allowing soil to dry out completely.

 

dinosaur

any of that particular group of reptiles that dominated or were prominent among Mesozoic life forms. They are divided into two forms on the basis of pelvic structure: the Saurischia with the normal reptile pelvis structure, and the Ornithischia, in which the pelvis resembles that of a bird. They ranged in size from 30cm to 26m. They were carnivorous, herbivorous, bipedal or quadrupedal. Most were terrestrial, but there were also aquatic and semi-aquatic representatives. Range, Triassic to Cretaceous.

 

dolerite

a medium-grained intrusive igneous rock of basaltic composition, composed of the minerals pyroxene, plagioclase and iron-titanium oxides. It may be seen in the field as dykes and sills - feeding magma to form basalt lavas flows.

 

dyke

a tabular body of intrusive igneous rock that cuts across the layering or structural fabric of the host rock. It may be a composite or multiple intrusion.


 

Sources Consulted:
Farndon, J. (1998). Concise Encyclopedia Earth, Dorling Kindersley, Great Britain, 192.
Lapidus, D.F. (1987) Collins Dictionary of Geology, Winstanley, I. (Ed.), HarperCollins, Great Britain, 565pp.


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