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Ch 15 Science 8
Term | Definition |
---|---|
rock | the solid material in the earth’s crust, formed from one or more minerals or organic materials |
petrology | the study of rocks |
sedimentary rock | rocks made up of particles that have been bonded together by natural cements or of solids that have settled from water solutions |
igneous rock | rocks that have cooled from a molten mixture |
metamorphic rock | sedimentary or igneous rocks that were altered by agents such as heat and pressure |
rock cycle | a concept that describes how the earth’s rocks are recycled between the crust and the upper mantle |
strata | A layer of sedimentary rock |
clastic | fragmental; rocks that have been bonded together by natural cements |
nonclastic | chemical; rocks made of solids that have precipitated or evaporated from water solutions |
matrix | a material in which something else is enclosed or embedded |
porosity | ratio of the volume of empty space between the particles in a rock to its total volume |
permeable | the ability of a rock to permit liquids and gases to pass through its pores |
precipitate | the solid that crystallizes out of a super-saturated solution and settles to the bottom of the solution |
evaporite | evaporation of water can leave the minerals behind |
fossil | any trace or remains of a living organism that has been preserved by natural means |
paleontology | the study of fossilized plants and animals |
index fossils | or “guide fossils”; fossils that seemingly linked layers of rock together to a corresponding time |
fossil fuels | natural solid, liquid, and gas materials that appear to come from fossilized remains of plants and animals |
magma | molten rock found beneath the earth’s surface |
lava | molten rock that flows out onto the earth’s surface |
extrusive | form when lava solidifies above the earth’s surface |
intrusive | formed beneath the earth’s surface, but may appear at earth’s surface because of erosion |
sill | an igneous rock intrusion that cuts horizontally across the original sedimentary rock strata |
dike | a vertical sheet of intrusive igneous rock that has been forced between existing rock strata |
local metamorphism | small-scale process when magma heats and compresses the surrounding rock materials, altering their crystal structure and chemical composition |
regional metamorphism | occurred over large areas because of the heat and pressure from immense forces---forces that folded great tracts of rock, lifted mountains, and pushed plates of the earth’s crust together |
foliated | layered or banded |
nonfoliated | not layered, tend to break into sharp, angular pieces |
polystrate fossils | fossils that extend through several layers of sedimentary rock |
Geologic column | a sequence of rock units and layers that supposedly extends through time from the earliest known rocks to the recently deposited mud, gravel, and sand |