Geologic Miscellany


Dendritic
(adjective) Tree-like. A drainage pattern resembling branches of a tree.
Felsic
Adjective applied to light-colored rocks -- usually igneous or metamorphic -- containing significant quantities of feldspar.
Iapetus
Ocean existing about 650-300 million years ago; ancient analog of modern Atlantic Ocean. Father of Atlas in Greek mythology.
Limesink
Large pit resulting from collapse of subterranean cavern dissolved in limestone. Common in Florida and south Georgia. Often a result of lowered water table.
Mafic
Adjective applied to dark-colored rocks -- usually igneous or metamorphic -- containing sigificant quantities of ferromagnesian (iron- or magnesium-bearing) minerals. "MA" for magnesium; "F" for iron.
Pangea
Postulated and probable ancient supercontinent incorporating all major land masses. Assembled about 300 My ago; fragmented about 200 My ago.
Proto-Africa
Ancient continent; analog of modern Africa, existing before assembly of Pangea.
Proto-North America
Ancient continent; analog of modern North America, existing before assembly of Pangea.
Saprolite
"Rotten" rock, altered by weathering (often decomposition of feldspars) into crumbly, disaggregated material. May retain original rock structure. Intermediate between rock and soil.
Trilobite
Extinct three-lobed marine animal; distant relative of horseshoe crab. Common fossil in Paleozoic deposits.
Ultramafic
Adjective applied to black or dark green rocks -- usually igneous or metamorphic -- containing large quantities of ferromagnesian (iron- and magnesium-bearing) minerals.