Essential Question: summarize Essential Question: summarize the development of the the development of the

geologic column and its Major geologic column and its Major units of timeunits of time

18.1 The Geologic Time Scale18.1 The Geologic Time Scale

Homework:5/8 vocabulary page 360 – define and give one fact5/6 section review page 346

18.1 The Geologic Time Scale18.1 The Geologic Time Scalegeologic columngeologic column an ordered arrangement of an ordered arrangement of

rock layers that is based on the relative ages of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the rocks and in which the oldest rocks are at the bottom.the bottom.

► Evidence of changing conditions on Earth’s Evidence of changing conditions on Earth’s surface is recorded in the rock layers of Earth’s surface is recorded in the rock layers of Earth’s crust.crust.

► The geologic time scale outlines the The geologic time scale outlines the development of Earth and of life on Earth.development of Earth and of life on Earth.

The Geologic ColumnThe Geologic Column► Rock layers in a geologic column are Rock layers in a geologic column are

distinguished by the types of rock the layers distinguished by the types of rock the layers are made of and by the kinds of fossils the are made of and by the kinds of fossils the layers contain.layers contain.

► Fossils in the upper layers resemble modern Fossils in the upper layers resemble modern plants and animals.plants and animals.

►Many of the fossils discovered in old layers are Many of the fossils discovered in old layers are from species that have been extinct for millions from species that have been extinct for millions of years.of years.

Divisions of Geologic TimeDivisions of Geologic Time► The geologic history of Earth is marked by The geologic history of Earth is marked by

major changes in Earth’s surface, climate, and major changes in Earth’s surface, climate, and types of organisms. types of organisms.

► Geologists use these indicators to divide the Geologists use these indicators to divide the geologic time scale into smaller units.geologic time scale into smaller units.

► Rocks grouped within each unit contain similar Rocks grouped within each unit contain similar fossils and each unit is generally characterized fossils and each unit is generally characterized by fossils of a dominant life-form. by fossils of a dominant life-form.

Earth-History ClockEarth-History Clock►EonEon

EraEra►PeriodPeriod

EpochEpoch

EonsEons►The largest unit of geologic time is an The largest unit of geologic time is an eoneon. .

Geologic time is divided into four eons: the Geologic time is divided into four eons: the Hadean eon, the Archean eon, the Hadean eon, the Archean eon, the Proterozoic eon, and the Phanerozoic eon.Proterozoic eon, and the Phanerozoic eon.

►the Hadean eon, the Archean eon, the the Hadean eon, the Archean eon, the Proterozoic eon = Precambrian Time. This Proterozoic eon = Precambrian Time. This 4 billion year interval contains most of 4 billion year interval contains most of Earth’s history.Earth’s history.

ErasEraseraera a unit of geologic time that divides a unit of geologic time that divides

eons into smaller units of time.eons into smaller units of time.

►Only the Phanerozoic eon is divided Only the Phanerozoic eon is divided into eras.into eras.

►Examples: Paleozoic, Mesozoic, and Examples: Paleozoic, Mesozoic, and Cenozoic erasCenozoic eras

PeriodsPeriodsperiodperiod a unit of geologic time that a unit of geologic time that

divides eras into smaller units of time.divides eras into smaller units of time.

►Eras are divided into shorter time units Eras are divided into shorter time units called periods. Each period is called periods. Each period is characterized by specific fossils.characterized by specific fossils.

►Example periods: Devonian, Jurassic, Example periods: Devonian, Jurassic, Quaternary periods.Quaternary periods.

EpochsEpochsepochepoch a subdivision of geologic time that a subdivision of geologic time that

divides periods into smaller units of time.divides periods into smaller units of time.►Where the rock record is most complete, Where the rock record is most complete,

a detailed fossil record may allow a detailed fossil record may allow scientists to divide periods into shorter scientists to divide periods into shorter time units called epochs. time units called epochs.

►Examples: Paleocene, Pleistocene, Examples: Paleocene, Pleistocene, Holocene epochs.Holocene epochs.

Essential Question: Identify the Essential Question: Identify the Characteristics of Precambrian Rock Characteristics of Precambrian Rock and what has been learned of life in and what has been learned of life in the Paleozoic era, Mesozoic era and the Paleozoic era, Mesozoic era and Cenozoic eraCenozoic era

18.2 Geologic History18.2 Geologic History

EvolutionEvolutionevolutionevolution an inheritable change in the an inheritable change in the

characteristics within a population from one characteristics within a population from one generation to the next; the development of generation to the next; the development of new types of organisms from preexisting types new types of organisms from preexisting types of organisms over time.of organisms over time.

► By examining rock layers and fossils, scientists By examining rock layers and fossils, scientists have discovered evidence that species of have discovered evidence that species of living things have changed over time. living things have changed over time.

► Scientists call this process evolution.Scientists call this process evolution.

Evolution and Geologic Evolution and Geologic ChangeChange

► Scientists think that evolution occurs by Scientists think that evolution occurs by means of means of natural selectionnatural selection. Evidence for . Evidence for evolution included the similarity in skeletal evolution included the similarity in skeletal structures of animals.structures of animals.

► Major geologic and climatic changes can affect Major geologic and climatic changes can affect the ability of some organisms to survive.the ability of some organisms to survive.

► By using geologic evidence, scientists try to By using geologic evidence, scientists try to determine how environmental changes determine how environmental changes affected organisms in the past.affected organisms in the past.

EvolutionEvolution

Precambrian RocksPrecambrian Rocks►Precambrian time is from 4.6 billion years Precambrian time is from 4.6 billion years

ago to about 540 million years ago, stared ago to about 540 million years ago, stared when the Earth’s crust cooled enough for when the Earth’s crust cooled enough for rocks to form.rocks to form.

►The rock material has been completely The rock material has been completely changed by the process of plate tectonics changed by the process of plate tectonics and metamorphismand metamorphism

►Exposed Precambrian rock is call a shield Exposed Precambrian rock is call a shield and can be found on every continent, half and can be found on every continent, half of all valuable minerals are here. (gold, of all valuable minerals are here. (gold, iron, nickel, and copper)iron, nickel, and copper)

Precambrian RocksPrecambrian Rocks►Fossil are a rare find, the most common is Fossil are a rare find, the most common is

a Stromatolites, which formed from a Stromatolites, which formed from cynobateriacynobateria

►This implies shallow seas, the imprints of This implies shallow seas, the imprints of worms, jellyfish, and one celled worms, jellyfish, and one celled organisms have been found late in organisms have been found late in Precambrian rocks Precambrian rocks

The Paleozoic EraThe Paleozoic Era►Started 540 million years ago and Started 540 million years ago and

ended 248 million years agoended 248 million years ago►The continents came together during The continents came together during

this time and there was abundant life in this time and there was abundant life in the oceans and on landthe oceans and on land

►This era has been divided into seven This era has been divided into seven periods: Cambrian, Ordovician, Silurian, periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian Devonian, Carboniferous and Permian

The Cambrian periodThe Cambrian period►During this period there was an explosion During this period there was an explosion

of marine life, trilobites been one of there of marine life, trilobites been one of there marker index fossils used to date the marker index fossils used to date the different periods.different periods.

►Brachiopods also formed during this time Brachiopods also formed during this time and still exist todayand still exist today

►The fossil record is rich because animals The fossil record is rich because animals developed hard shells during this period.developed hard shells during this period.

►There is no evidence of life on land in this There is no evidence of life on land in this periodperiod

The Ordovician PeriodThe Ordovician Period►More brachiopods developed and the More brachiopods developed and the

trilobites began to decline, snail clams trilobites began to decline, snail clams and other mollusk became the and other mollusk became the dominate life formsdominate life forms

►The first fish with a vertebrate The first fish with a vertebrate developed in this period, no jaws or developed in this period, no jaws or teeth and it had bony platesteeth and it had bony plates

►Still no life on landStill no life on land

The Silurian PeriodThe Silurian Period►During this time both invertebrate and During this time both invertebrate and

vertebrate creatures thrivedvertebrate creatures thrived►Echinoderms (sea stars) and corals Echinoderms (sea stars) and corals

became more numerous, as well as became more numerous, as well as eurypterids ( a scorpion like creature) eurypterids ( a scorpion like creature) that reach 2.7 m in length.that reach 2.7 m in length.

►Early plant life formed and spiders and Early plant life formed and spiders and millipedes evolvedmillipedes evolved

The Devonian PeriodThe Devonian Period►This is the age of fish, a population This is the age of fish, a population

explosion of fish caused adaptations explosion of fish caused adaptations like air breathing fish or lung fishlike air breathing fish or lung fish

►Amphibians probably evolved from Amphibians probably evolved from these fishthese fish

►Land plants, giant horsetails, ferns and Land plants, giant horsetails, ferns and cone bearing plantscone bearing plants

The Carboniferous PeriodThe Carboniferous Period►This is the period, it is believed, that This is the period, it is believed, that

coal and oil formedcoal and oil formed► It is also a time when it was warmer It is also a time when it was warmer

and more humid world wide, swamps and more humid world wide, swamps and forest covered most of the landand forest covered most of the land

► Insects dominated the land and at the Insects dominated the land and at the end of the period the first lizards end of the period the first lizards evolvedevolved

The Permian PeriodThe Permian Period►Was the first mass extinction, many Was the first mass extinction, many

marine life disappeared forevermarine life disappeared forever►The land joined together to form The land joined together to form

PangaeaPangaea►Reptiles flourished in this new Reptiles flourished in this new

environmentenvironment

The Mesozoic EraThe Mesozoic Era►248 million years ago to 65 million years 248 million years ago to 65 million years

agoago►The planet was warm and humidThe planet was warm and humid►Pangaea broke apart, tectonic plates Pangaea broke apart, tectonic plates

collide and formed new mountain ranges collide and formed new mountain ranges ►Reptiles like lizards, turtles, crocodiles, Reptiles like lizards, turtles, crocodiles,

snakes and dinosaurs … the age of reptilessnakes and dinosaurs … the age of reptiles►Broken into three periods; Triassic, Broken into three periods; Triassic,

Jurassic, and cretaceous Jurassic, and cretaceous

The Triassic PeriodThe Triassic Period►Dinosaurs first appeared, some as small Dinosaurs first appeared, some as small

as a squirrel and others up to 30 m as a squirrel and others up to 30 m ►most about 4 to 5 meters, could move most about 4 to 5 meters, could move

quicklyquickly►The land was covered with cone bearing The land was covered with cone bearing

trees and palmstrees and palms►The even inhabited the oceans The even inhabited the oceans ►Mammals first appeared in the forest and Mammals first appeared in the forest and

about the size of a rodentabout the size of a rodent

The Jurassic PeriodThe Jurassic Period►Dinosaurs dominated, two types Dinosaurs dominated, two types

saurischians (lizard hip) and saurischians (lizard hip) and ornithischians (bird hip)ornithischians (bird hip)

►Lizard hip included herbivores and Lizard hip included herbivores and carnivores, the largest was Apatosaurus carnivores, the largest was Apatosaurus at 25 meters and 50 tonsat 25 meters and 50 tons

►The stegosaurs was part of the bird hipThe stegosaurs was part of the bird hip►Pterosaurs was a flying dinosaur and the Pterosaurs was a flying dinosaur and the

first feather bird appeared at this time.first feather bird appeared at this time.

The Cretaceous PeriodThe Cretaceous Period►Dinosaurs still ruled the world with a Dinosaurs still ruled the world with a

great variety of creatures and T-Rex as great variety of creatures and T-Rex as the apex predatorthe apex predator

►Plant life also evolved into angiosperm, Plant life also evolved into angiosperm, which means they flower and fruitwhich means they flower and fruit

►A mass extinction ended this period, no A mass extinction ended this period, no dinosaur fossils found after this perioddinosaur fossils found after this period

Mass ExtinctionsMass Extinctions

The Cenozoic EraThe Cenozoic Era►65 million years ago to the present65 million years ago to the present►Continents close to current positions, Continents close to current positions,

tectonic activity increased forming the Alps tectonic activity increased forming the Alps and Himalayasand Himalayas

►Major climate change, mammals become Major climate change, mammals become dominate life on the planet.dominate life on the planet.

►Two periods; tertiary and quaternaryTwo periods; tertiary and quaternary►Seven epochs; paleocene, eocene, Seven epochs; paleocene, eocene,

oligocene, miocene, pliocene (tertiary), oligocene, miocene, pliocene (tertiary), pleistocene and holocene (quaternary)pleistocene and holocene (quaternary)

Paleocene and EocenePaleocene and Eocene►Mammal evolution took offMammal evolution took off►The first primates evolved, lemursThe first primates evolved, lemurs►The worldwide temperature dropped 4 The worldwide temperature dropped 4

degrees celsiusdegrees celsius

Oligocene and MioceneOligocene and Miocene►The large mammals developed in this The large mammals developed in this

time as the planet grows coldertime as the planet grows colder►Sea levels dropped and the polar ice Sea levels dropped and the polar ice

caps formedcaps formed►Deer, horses, camels, cats, dogs, Deer, horses, camels, cats, dogs,

raccoons, wolves, pigs and saber tooth raccoons, wolves, pigs and saber tooth catcat

PliocenePliocene►Fully evolved dogs, cats, bears and Fully evolved dogs, cats, bears and

horse appeared in this epochhorse appeared in this epoch►The ice age started and land bridges The ice age started and land bridges

between the continents formed between the continents formed allowing the animals to travelallowing the animals to travel

Pleistocene and HolocenePleistocene and Holocene►There where several ice ages in this time, There where several ice ages in this time,

with some animals developing thick fur or with some animals developing thick fur or migrating to warmer climates and some migrating to warmer climates and some went extinct altogetherwent extinct altogether

►Humans first appeared as huntersHumans first appeared as hunters►The Holocene started 11,000 years ago The Holocene started 11,000 years ago

with the end of the ice age, Homo sapiens with the end of the ice age, Homo sapiens developed agriculture and use tools made developed agriculture and use tools made from metals from metals