Earth History 8E21 - Fossils & Geologic Time Flashcards
remains or traces of animals, plants and other organisms from the past; usually at least 10000 years old
Fossils
fossil known to have lived in a particular geologic age that can be used to determine the date of the rock layer in which it was found
Index Fossil
a fossil that must be studied microscopically
microfossil
forms when sediments bury an organism and the sediments change into rock; the organism decays leaving a cavity in the shape of the organism
mold fossil
forms when the mud or sand hardens to stone where a footprint, trail, or burrow of an organism was left behind
trace fossil
forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber
preserved fossil
forms when organisms or parts, like leaves, stems, flowers, fish, are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock
carbonized fossil
forms when a mold is filled with sand or mud that hardens into the shape of the organism
cast fossil
forms when minerals soak into the buried remains, replacing the remains, and changing them into rock
petrified fossil (permineralized fossil)
measurement of the known rates of decay of radioactive materials that an object contains in order to determine the age of the object
Absolute (radioactive)Dating
states that in undisturbed rock layers that newer layer will be deposited over older layers
Law of Superposition
states rock layers that cut across other rock layers are younger than those they cut
Law of Crosscutting Relationships
determining the age or order of things from the past or past events without knowing or calculating the actual age
Relative Age Dating
rock formed by deposition of sand, clay and other pieces of rock that are compacted together under pressure
Sedimentary rock
radioactive heavy metal that is an abundant source of nuclear energy (14 known isotopes, used in radioactive dating)
uranium
fracture along which blocks of the Earth’s crust that can be caused by the shifting or dislodging of the Earth’s crust. Types include normal, strike slip, or reverse
Fault
system of chronological measurement that relate to the history of events in Earth’s past, consisting of fossils and major events
Geologic Time Scale
a core sample of ice removed from a sheet of ice. Properties of the ice and the crystallized components in the ice are used to reconstruct climatic record
Ice Core
type of rock formed under or above ground when magma or lava cools
Igneous rocks
rock created from the transformation of other types of rock through heat and pressure
Metamorphic rock
the crust that makes up the continents
Continental Plate
the change in a geographic area caused by earthquakes, volcanoes, mountains forming, and other natural phenomena.
Geographic Change
the study of the rocks, processes, and history of Earth
Geology
the part of Earth’s crust that underlies the oceans
Oceanic Plate
the movement or study of the movement of Earth’s crust (the movement of the tectonic plates is responsible for geologic and subsequent biologic change over time)
Plate Tectonics
more dense tectonic plate dives under another, forms trench, causes volcanos, and earthquakes (Andes Mountains)
convergent plate boundary
process in which sediment is laid down in new locations (via glaciers, water, wind, gravity)
deposition
two plates moving away from each other, separating, spreading apart
divergent plate boundary
the process of wearing or grinding something down
erosion
the end of the last type of a specific individual or a group of species (the capability to reproduce and survive is lost)
extinction
when the land is forced together at a convergent plate boundary
folding
when two oceanic plates pull apart, magma rises and new crust is formed
sea-floor spreading
material deposited by water, wind, or glaciers
sediment
molten (liquid) rock that reaches the Earth’s surface
lava
a strike-slip fault that occurs typically between segments of a mid-ocean ridge or other tectonic-plate boundary and that is characterized by shallow high-magnitude earthquakes
transform fault
serve as excellent index fossils, enabling geologists to date the age of the rocks in which they are found, and possibly the second-most famous fossil group after the dinosaurs
trilobites
Earth’s crust and rigid part of the upper mantle
lithosphere
molten (liquid) rock beneath the Earth’s surface
magma
a divergent boundary in the ocean where new sea floor is being made
mid-ocean ridge
a hypothetical continent including all the landmass of the earth
Pangaea
a process that explains the basic relationships among igneous, metamorphic, and sedimentary rocks
rock cycle
a fissure in the earth’s crust through which gases erupt
volcano
disintegration or alteration of rock in its natural or original position at or near the Earth’s surface through physical, chemical, and biological processes induced or modified by wind, water, and climate
weathering
the layer of the Earth below the crust and above the core
mantle
a bowl-shaped geological formation at the top of a volcano
crater
a large crater caused by the violent explosion of a volcano
caldera
a rocky object that orbits the sun and has an average size between a meteoroid and a planet
asteroid
a stratum (layer) of rock (especially sedimentary rock)
bed (in geology)
the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature
Big Bang Theory
a ravine formed by a river in an area with little rainfall
canyon
a shift in the world’s average weather and temperature
climate change
one of the large landmasses of the earth
continent
the gradual movement of very large land masses
continental drift
the outer layer of the Earth
crust
the organic phenomenon of rotting
decay
vibration from underground movement along a fault plane
earthquake
the longest unit of geological time
eon
a unit of geological time that is divided into ages
epoch
a major division of geological time
era
the sudden occurrence of a violent discharge
eruption
sequence of events involved in the development of a species
evolution
the state of being no longer in existence
extinction
the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)
half-life
a stony or metallic object from space that hits the earth
meteorite
a series of hills or mountains
mountain chain
the earth science that studies fossil organisms
paleontology
a unit of geological time when a system of rocks formed
period
the process of turning some plant material into stone
petrifaction
a rigid layer of the Earth’s crust
plate
belonging to or existing before recorded times
prehistoric
a long narrow natural elevation or striation
ridge
