Eras
Geologic time intervals based on the sequence of rock strata and different life forms.
Precambrian Era
4600 to 600 million years ago; characterized by bacteria and worms.
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Flashcards about Geology
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Eras
Geologic time intervals based on the sequence of rock strata and different life forms.
Precambrian Era
4600 to 600 million years ago; characterized by bacteria and worms.
Paleozoic Era
600 to 225 million years ago; characterized by reptiles, insects, and land plants.
Mesozoic Era
225 to 65 million years ago; characterized by dinosaurs, birds, and flowering plants.
Cenozoic Era
65 million years ago to today; characterized by mammals and grasses.
Fossils
Traces of once-living things that are preserved in rocks.
Paleontologist
A scientist who studies early lifeforms by interpreting fossils.
Mold
An empty shape formed in rock (such as a skeleton decaying).
Cast
When a mold is filled with rock or minerals.
Strata
Layers of sediment that have formed over millions of years where fossils are found.
Index Fossils
Fossils that can be used to identify a particular time period or era.
Petrified Fossil
Formed when minerals replace the structure of an organism.
Carbonaceous Film
A very thin layer of living material that has been compressed in rock.
Original Remains
An actual body or body part of an organism.
Trace Fossils
Things left behind by ancient creatures, such as a footprint, nests, or scat.
Continental Drift
How continents moved to their current locations in geologic time.
Pangaea
At one time, all the landmass together.
Theory of Plate Tectonics
The idea that the continental crust is broken up into large areas called plates that are moving very slowly in various directions.
Convection Current
Pattern of moving liquid or gas particles when heat energy is transferred to a substance.
Plates
Continental and oceanic crust segments of the Earth
Ridges
Mountain chains that rise from the ocean floor.
Trenches
Deep valleys on the ocean floor.
Subduction
Collision between the oceanic and continental plates where the dense ocean plate slides below the lighter continental plate.
Divergent Boundary
When neighboring plates are moving away from one another.
Convergent Boundary
Where neighboring plates are moving towards one another.
Transform Boundary
When neighboring plates are sliding past one another.
Mountain
Part of Earth's surface that is much higher than the land around it.
Mountain Range
A series of mountains formed when continental tectonic plates collide.
Mountain Building
The process of creating mountains.
Folds
Bends that form in rock.
Anticline
Upward fold
Syncline
Downward fold.
Faults
Large cracks that form from breakage.