Assignment 14. Review
Scientists think the earth is approximately _____ years old.
4 ½ billion
According to stratigraphy and its laws, what is the correct order—from oldest to youngest, of the following rock strata:
A, B, C, D
Match each eon with the appropriate characteristic or event.
Hadean eon- formation of the solar system Archean eon- toxic atmosphere; first bacteria Proterozoic eon- buildup of oxygen; first eukaryotes Phanerozoic eon- current eon
The era that is defined by both a huge explosion in the diversity of life as well as the largest mass extinction is the _____.
Paleozoic
fossil record
The placement of fossils throughout the surface layers of the Earth that are used as a guide for determining when life forms existed, and how they evolved.
paleoanthropology
The study of early forms of humans and their primate ancestors.
taphonomy
The study of the conditions under which plants, animals, and other organisms become altered after death and sometimes preserved as fossils.
index fossil
a fossil that is widespread geographically but only occurs in one layer or a small number of layers of rock
molecular clock
a technique for estimating the age of species by comparing molecular differences between species
The Cretaceous-Tertiary extinction, the most famous of the Big Five, has been attributed to what major event(s) that triggered the extinction of the dinosaurs?
an asteroid hitting the earth massive volcanoes erupting around the world
The longest interval of time is called _____.
an eon
law of faunal and floral succession
animals and plant fossils occur in consistent sequences through time, generally changing from simpler to more complex
transition fossil
any fossil which gives us information about a transition from one species to another.
law of superposition
any undisturbed sequence of layered rocks has the oldest rock on the bottom and newest rock on the top
radiometric dating
dating a rock or mineral by measuring the proportions of an original radioactive material and its decay products
The climate of the earth throughout history has always _____.
fluctuated between hot and cold periods
uniformitarianism
geologic principle that Earth's processes act in the same manner today as they always have throughout Earth's history
absolute time
geologic time measured in a specific duration of years
law of cross-cutting (or intrusive) relationships
in a sequence of layered rocks, the crosscut, or intrusive feature, is younger than the layers it intercedes
climate
long-term weather patterns of a particular area
eon
longest interval of geologic time
era
major divisions of geologic time within each eon; identified by major changes in the fossil record
period
major divisions of geologic time within each era; identified by changes in the fossil record
relative time
placing events in chronological order without reference to their ages measured in years
rifting
process by which the earth's crust is pulled apart and new crust forms
Geological evidence of the age of the earth includes _____.
radiometric dating of rocks fossil evidence gradual processes of rock formation
law of original horizontality
sediment deposited into water will settle at the bottom in flat, horizontal layers
law of original lateral continuity
sediment deposited into water will spread in a horizontal and continuous sheet
paleontology
study of fossils
stratigraphy
study of rock layers and the processes that form them
excavation
the action of excavating (unearthing) something, especially at an archaeological site.
atmosphere
the gaseous envelope of a planet
sedimentation
the natural process in which material is carried to the bottom of a body of water and forms a solid layer.
mass extinction
the process in which huge numbers of species die out suddenly
In order to accurately determine absolute time, you need to know which of the following?
the rate at which radioactive decay occurs how much radioactive decay has occurred
decomposition
the state or process of rotting or decay.
catastrophism
theory that Earth's rock layers formed in a global flood followed by the uplifting of rocks and mountain building over a short, violent period, possibly in the recent past
fossils
traces, remains, or impressions of a prehistoric organism preserved in petrified form or as a mold or cast in rock.