click below
click below
Normal Size Small Size show me how
18weekassessment
Term | Definition |
---|---|
igneous rock | formed when magma cools and hardens |
magma | magma forms when rock melts |
crystalline | full of crystals |
intrusive | magma cools below ground; larger crystals |
extrusive | magma cools above ground |
coarse-grained | generally light colored with dark crystals spread throughout |
fine-grained | small grains invisible to the human eye |
porphyritic | rock with a mix of large and small crystals; granite is an example |
glassy | few or no crystals; obsidian is an example |
vesicular | many holes inside and outside; pumice is an example |
felsic | rich in minerals that form feldspar and quartz |
mafic | contains a group of dark colored minerals |
compaction | sediment progressively loses its porosity due to the effects of loading |
chemical sedimentary rock | formed when minerals, dissolved in water, begin to precipitate out of solution and deposit at the base of the water body |
organic sedimentary rock | contains significant amounts of organic carbon |
clastic sedimentary rock | form by weathering processes which break down rocks into pebble, sand, or clay particles by exposure to wind, ice, and water |
sorting | the tendency for currents of air or water to separate sediments according to size |
cementation | hardening and welding of clastic sediments by the precipitation of mineral in the pore spaces |
angularity | used to describe the shape of the corners on a particle of sediment |
stratification | the layering of rocks |
cross-bedding | horizontal units that are internally composed of inclined layers |
ripple marks | sedimentary structures and indicate agitation by water or wind |
mud cracks | when muddy deposits dry and shrink |
concretions | lumps of rock that have a composition that is different from that of the main body |