Transcript Paleo Test Review

Paleo Test
Review Guide

Hutton’s principal of uniformitarianism
states….
-current geologic processes are the
same processes that were at work in
the past.

Relative age indicates…
-one layer of rock is older or younger
than another layer. It does not tell an
exact numerical age.

The law of superposition states…
-an undeformed sedimentary rock layer
is older than the layers above it and
younger than the layers below it.

The principle of original horizontality
states…
-sedimentary rocks left undisturbed will
remain in horizontal layers.

A break in the geologic record is an….
-unconformity.

Three types of unconformity…
-nonconformity, angular unconformity,
and a disconformity.

Absolute age is…
-the numerical age of something.

The law of crosscutting relationships
states…
-a fault or igneous intrusion is always
younger than the rock layers it cuts
through.

Four ways to determine absolute age
are…
-rates of erosion, rates of deposition,
varve count, and radiometric dating.

Radiometric dating is…
-using radioactive decay to measure
absolute age.

What are isotopes?
-atoms of the same element that have
different numbers of neutrons.

What is half-life?
-amount of time it takes half the mass of
a given amount to decay into its
daughter isotopes.

Carbon-14 is an isotope. What is it’s
effective dating range?
-less than 70,000 years.

The remains of animals or plants that
lived in a previous geologic time are
called….
-fossils

The study of fossils…
-paleontology.

Almost all fossils are found in what
type of rock?
-sedimentary rock

What are the five main ways fossils
can be formed?
-mummification, amber, tar seeps,
freezing, and petrification.

The four main types of fossils are…
-imprints, molds & casts, coprolites,
gastroliths, and trace fossils.

Index fossils…
-occur only in rock layers of a particular
geologic age. Can be used to estimate
absolute ages of specific rock layers.

What is a geologic column?
-represents a timeline of Earth’s history.
The oldest rocks are at the bottom
and the youngest are towards the top.

What are the four main eras?
-precambrian, paleozoic, mesozoic,
cenozoic

The Devonian Period is best known
as…
-The Age of the Fishes!

What is the leading theory on how the
dino’s became extinct?
-meteorite impact hypothesis.

What era is considered the Age of the
Mammals?
-Cenozoic Era

What are the most common types of
fossils you would expect to find dating
back to Precambrian Time?
-stromatolites

What are the three periods of the
Mesozoic Era?
-Triassic, Jurassic, and the Cretaceous

The largest unit of geologic time is
called…
-an Eon.

The gradual development of new
organisms from preexisting organisms
is called?
-evolution

Large areas of exposed Precambrian
rocks found on every continent are
called…
-shields

Coal deposits found in Pennsylvania,
Ohio, and West Virginia can be linked
to what period?
-Carboniferous Period

When and what caused the
Appalachian Mountains to form?
-End of the Permian period (Paleozoic
Era), the collision of the continents
forming into Pangea.

The Mesozoic Era is also known as
the…
-Age of Reptiles

The Cenozoic Era is also called the…
-Age of Mammals

What mountain ranges were created in
the Cenozoic Era?
-Alps, Himilayas

Mountain ranges created in the
Mesozoic Era include…
-Sierra Nevada’s and the Andes

A decrease in temperatures during the
Cenozoic Era resulted in…
-new species of animals being
developed.

Explain the concept of evolution as
brought on by geologic change.
-figure this one out on your own!

What period and era mark the end of
the dino’s?
-end of the Cretaceous period, Mesozoic
Era.

What method of dating seems to be
the most accurate?
-radiometric dating.