Geologic Time ScaleGeologic Time Scale

Ch 18Ch 18

Geologic Time ScaleGeologic Time Scale

Law of superposition- youngest Law of superposition- youngest is on top oldest on bottomis on top oldest on bottom

Geologic column- arrangement Geologic column- arrangement of rock layersof rock layers

Era- A very large unit of timeEra- A very large unit of time Period-A division of an EraPeriod-A division of an Era Epoch-A division of a PeriodEpoch-A division of a Period

Section 18.1 reviewSection 18.1 review

Scientists use events such as Scientists use events such as major changes in the earth’s major changes in the earth’s surface and climate and the surface and climate and the extinction of various species as extinction of various species as the basis for dividing the the basis for dividing the geologic time scale into units.geologic time scale into units.

True

Section 18.1 reviewSection 18.1 review

Using the law of superposition Using the law of superposition and the study of index fossils, and the study of index fossils, nineteenth century scientists nineteenth century scientists determined the relative ages of determined the relative ages of rock layersrock layers

True

False Eras are subdivisions of periodsEras are subdivisions of periods

Section 18.1 reviewSection 18.1 review

False Scientists can use the geologic Scientists can use the geologic

column to estimate the relative column to estimate the relative ages of rock layers only if the ages of rock layers only if the rock contains radioactive rock contains radioactive mineralsminerals

Fossils of mammals are Fossils of mammals are common in Cenozoic rockscommon in Cenozoic rocksTrue

Complete the statementComplete the statement

Rock layers in the geologic Rock layers in the geologic column can be distinguished column can be distinguished from one another according to from one another according to rock type and__________rock type and__________

The geologic era that followed The geologic era that followed Precabrian time is called the Precabrian time is called the __________________

Fossil content

Paleozoic Era

Complete the statementComplete the statement

According to the geologic According to the geologic column in the diagram, the column in the diagram, the oldest rock layer is__________oldest rock layer is__________

Based on late Precambrian Based on late Precambrian fossils and other types of fossils and other types of geological evidence, scientists geological evidence, scientists theorize that life began theorize that life began __________________

Layer 4

In the ocean

Last question in 18.1Last question in 18.1

The era that is divided into The era that is divided into epochs is the ___________epochs is the ___________Cenozoic Era

Theory of EvolutionTheory of Evolution Organisms change over time. Organisms change over time.

New kinds of organisms are New kinds of organisms are derived from ancestors.derived from ancestors.

Precambrian timePrecambrian time

Started 4.6billion years agoStarted 4.6billion years ago Ended 540million years agoEnded 540million years ago Characteristics of this time:Characteristics of this time:

Soft-bodies or single cell Soft-bodies or single cell organisms, Stromatolitesorganisms, Stromatolites

Lots of volcanoes, mountain Lots of volcanoes, mountain formation, sediment formation & formation, sediment formation & metamorphismmetamorphism

Paleozoic Era Paleozoic Era 540-248 million years ago540-248 million years ago

Periods:Periods: Cambrian Cambrian OrdovicianOrdovician SilurianSilurian DevonianDevonian CarboniferousCarboniferous PermianPermian

Paleozoic Era Paleozoic Era 540-248 million years ago540-248 million years ago

Cambrian Cambrian Advanced forms of marine life and Advanced forms of marine life and

first invertebrates appearfirst invertebrates appear OrdovicianOrdovician

Brachiopods increase: trilobites Brachiopods increase: trilobites decline: graptolites flourish: First decline: graptolites flourish: First vertebrates (fishes appear)vertebrates (fishes appear)

Paleozoic Era Paleozoic Era 540-248 million years ago540-248 million years ago

SilurianSilurian First land plants and animals First land plants and animals

appearappear DevonianDevonian

Age of fishesAge of fishes First amphibiansFirst amphibians Ferns and cone bearing plantsFerns and cone bearing plants

Paleozoic Era Paleozoic Era 540-248 million years ago540-248 million years ago

CarboniferousCarboniferous Split into two epochs: Split into two epochs:

Mississippian and PennsylvanianMississippian and Pennsylvanian Amphibians flourishAmphibians flourish Giant cockroachesGiant cockroaches

PermianPermian Pangaea comes together mass Pangaea comes together mass

extinctionsextinctions

Mesozoic EraMesozoic Era248-65 million years ago248-65 million years ago

PeriodsPeriods TriassicTriassic

First Dinosaurs, tropical weather,First Dinosaurs, tropical weather, JurassicJurassic

Large Dinosaurs, tropical weather,Large Dinosaurs, tropical weather, CretaceousCretaceous

First flowering plants, mass extinctionFirst flowering plants, mass extinction

Cenozoic EraCenozoic Era65 million years to today65 million years to today

PeriodsPeriods TertiaryTertiary

PaleocenePaleocene OilgoceneOilgocene MioceneMiocene PliocenePliocene

QuaternaryQuaternary PleistocenePleistocene HoloceneHolocene

Cenozoic EraCenozoic Era65 million years to today65 million years to today

PeriodsPeriods TertiaryTertiary

Age of mammalsAge of mammals Pangaea separatesPangaea separates

QuaternaryQuaternary Ice age and human’s develop Ice age and human’s develop

18.2 review18.2 review

The presence of cross-bedded The presence of cross-bedded sandstone may indicate that the sandstone may indicate that the region where it is present was once: region where it is present was once:

Shields are large areas of exposed Shields are large areas of exposed rock of what era?rock of what era?

The fossil record indicates that which The fossil record indicates that which of the following thrived during the of the following thrived during the Paleozoic EraPaleozoic Era

A desert

Precambrian

Advanced forms of marine life

18.2 review18.2 review

The Devonian period is also The Devonian period is also known as the Age ofknown as the Age of

Dinosaurs first appeared during Dinosaurs first appeared during thethe

During which era did glaciers During which era did glaciers cover nearly one third of the cover nearly one third of the earth’s land area?earth’s land area?

Fishes

Triassic period

CenozicCenozic

18.2 review18.2 review

During which epoch did the first During which epoch did the first modern horses appear?modern horses appear?

Which geologic period is Which geologic period is missing from this diagram?missing from this diagram?

PilocenePilocene

SilurianSilurian

The Paleozoic Era

Cambrian Ordovician_________Devonian

Time

18.2 review18.2 review

What are the most common What are the most common Precambrian fossils called?Precambrian fossils called?

Which period of the Cenozoic Which period of the Cenozoic Era includes the time before the Era includes the time before the last major ice agelast major ice age

StromatolitesStromatolites

TertiaryTertiary