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.