Dinosaurs Extinction TheoryDinosaurs Extinction Theory12-212-2

Objective: Give several points on each theory Objective: Give several points on each theory and give supporting evidence by writing a and give supporting evidence by writing a short essay using the notes.short essay using the notes.

Vocabulary Vocabulary

Extinction: there are no longer any living Extinction: there are no longer any living members of its kind or species.members of its kind or species.

# 1 Meteorite Theory# 1 Meteorite Theory

Meteorite impact on Earth (K-T Impact) Meteorite impact on Earth (K-T Impact)

Large meteorites collided w/earthLarge meteorites collided w/earth Threw dust and debris in the upper atmosphere Threw dust and debris in the upper atmosphere

Sun completely blocked outSun completely blocked out Plants could not carry out photosynthesis-diedPlants could not carry out photosynthesis-died Plant-eating dinosaurs- diedPlant-eating dinosaurs- died Meat-eating dinosaurs-diedMeat-eating dinosaurs-died

Layer of clay in sedimentary rock deposited at Layer of clay in sedimentary rock deposited at the same time as extinctionthe same time as extinction

Deformed grains of quartz/same as other Deformed grains of quartz/same as other meteorite cratersmeteorite craters

Clay-layer contain element iridium/rare on Clay-layer contain element iridium/rare on earth, commonly found in meteoritesearth, commonly found in meteorites

Evidence Evidence

#2 Volcanic-Greenhouse Theory#2 Volcanic-Greenhouse Theory Clay layer caused by volcanic eruptionClay layer caused by volcanic eruption

Change in global continental movementChange in global continental movement Large amount of continental activityLarge amount of continental activity Dust and debris in the upper atmosphere caused by Dust and debris in the upper atmosphere caused by

volcanic activityvolcanic activity Change in temperaturesChange in temperatures

Sun completely blocked outSun completely blocked out Plants could not carry out photosynthesis-Plants could not carry out photosynthesis-

dieddied Plant-eating dinosaurs- diedPlant-eating dinosaurs- died Meat-eating dinosaurs-diedMeat-eating dinosaurs-died

Evidence Evidence Layer of clay in sedimentary rock deposited Layer of clay in sedimentary rock deposited

at the same time as extinctionat the same time as extinction Deformed grains of quartz/same as seen Deformed grains of quartz/same as seen

around eruptionaround eruption Mass animal die offMass animal die off

#3 Natural Extinction#3 Natural Extinction Gradual disappearanceGradual disappearance Slow changes in environmentalSlow changes in environmental Possible shifts in continents caused by plate Possible shifts in continents caused by plate

tectonic shiftstectonic shifts

All organisms are dependent on their All organisms are dependent on their environments.environments.

Extinction: no more living members of a Extinction: no more living members of a species.species.

Bell WorkBell Work

1.1. The last species of dinosaurs became The last species of dinosaurs became extinct about _________ years ago.extinct about _________ years ago.

2.2. Louis and Walter Alvarez found a layer Louis and Walter Alvarez found a layer of clay containing ___________ and of clay containing ___________ and __________ that supported a meteorite-__________ that supported a meteorite-impact hypothesis.impact hypothesis.

3.3. The rock record indicates that global The rock record indicates that global temperatures _______ about 66 mya.temperatures _______ about 66 mya.

Fossils: 12-1 Fossils: 12-1

Objective:Objective:

List the conditions that is necessary for fossils to List the conditions that is necessary for fossils to occur by writing a description of the process.occur by writing a description of the process.

Standard:Standard:

S6C1-04: Describe how the rock and fossil record S6C1-04: Describe how the rock and fossil record show that environmental conditions have changed show that environmental conditions have changed over geologic and recent time. over geologic and recent time.

Vocabulary Vocabulary

Fossils: remains, imprints, traces of once Fossils: remains, imprints, traces of once living organisms preserved in rocks.living organisms preserved in rocks.

Petrified remains: hard and rocklike part or all Petrified remains: hard and rocklike part or all of an original materials in the remains have of an original materials in the remains have been replaced by minerals.been replaced by minerals.

Carbonaceous film: organism is pressed under Carbonaceous film: organism is pressed under sediment layer, some heat and gases, leaving thin sediment layer, some heat and gases, leaving thin film of carbon residue forming an outline of the film of carbon residue forming an outline of the original. original.

Carbonization: process of chemically changes Carbonization: process of chemically changes in organic material.in organic material.

Mold: pores in the rock let water and air reach Mold: pores in the rock let water and air reach the shell or hard part and it then decays, the shell or hard part and it then decays, leaving behind a cavity in the rock.leaving behind a cavity in the rock.

Cast: other sediments may fill in the cavity and Cast: other sediments may fill in the cavity and harden into the rock. Leaving a rock in the harden into the rock. Leaving a rock in the shape and form of the organism.shape and form of the organism.

Trace fossils: evidence left behind of an Trace fossils: evidence left behind of an organisms existence.organisms existence. TracksTracks Worm holesWorm holes Burrows Burrows

Original remains: organisms or parts of Original remains: organisms or parts of organisms are found in tacked in tree resin organisms are found in tacked in tree resin (amber), or ice glaciers.(amber), or ice glaciers.

La Brea Tara Pits, LA, CALa Brea Tara Pits, LA, CA

Conditions Necessary for Fossils to OccurConditions Necessary for Fossils to Occur

1)1) Dead organism must be protected from Dead organism must be protected from scavengers and microorganisms. Buried scavengers and microorganisms. Buried quickly by sediments.quickly by sediments.

2)2) Need hard parts such as bones, shells, teeth, Need hard parts such as bones, shells, teeth, soft parts decay quickly or are eaten by other soft parts decay quickly or are eaten by other organisms.organisms.

3)3) Usually found in sedimentary rock; heat Usually found in sedimentary rock; heat sedimentary rock coal. Original structure of sedimentary rock coal. Original structure of plants is lost when coal is formed. The first plants is lost when coal is formed. The first step is a fuel called peat. step is a fuel called peat.

Index fossils: Index fossils: species that exist for a relatively short period of species that exist for a relatively short period of

timetime Abundant and geographically widespreadAbundant and geographically widespread Very few fossils are classified or used as index Very few fossils are classified or used as index

fossilsfossils• Index fossils helpIndex fossils help

Determines the age of rocksDetermines the age of rocks Dates groups of fossilsDates groups of fossils Determines the types of environmentsDetermines the types of environments

Bell WorkBell Work

1.1. _________ are remains or traces of _________ are remains or traces of once-living organisms preserved in once-living organisms preserved in Earth’s rocks.Earth’s rocks.

2.2. When minerals replace the original When minerals replace the original material of an organism, the fossil that material of an organism, the fossil that forms is a(n) __________.forms is a(n) __________.

3.3. A(n) _______ forms when a thin film of A(n) _______ forms when a thin film of carbon is left behind after gases and carbon is left behind after gases and liquids are removed from an organism.liquids are removed from an organism.

Bell Work #2Bell Work #24. Sediment that fills a cavity and hardens forms 4. Sediment that fills a cavity and hardens forms a(n) __________ of the original organism.a(n) __________ of the original organism.

5. ___________ fossils are tracks and other 5. ___________ fossils are tracks and other evidence of animal activity.evidence of animal activity.

Relative Ages of RocksRelative Ages of RocksPrinciple of superposition Principle of superposition states that in an undisturbed states that in an undisturbed

layer of rock the oldest rocks are on the bottom and layer of rock the oldest rocks are on the bottom and the rocks become progressively younger (or more the rocks become progressively younger (or more recent) toward the top.recent) toward the top.

Relative dating Relative dating is used in geology to determine the is used in geology to determine the order of events and the relative age of rocks in a order of events and the relative age of rocks in a sequence.sequence.

Unconformities Unconformities develop when agents of erosion remove develop when agents of erosion remove existing rock layers; also form when a long period of existing rock layers; also form when a long period of time passes without any new deposition occurring to time passes without any new deposition occurring to form new layers of rock. form new layers of rock.

• Angular unconformities Angular unconformities is horizontal layers of is horizontal layers of sedimentary rock tilted and uplifted, so that sedimentary rock tilted and uplifted, so that agents of erosion and weathering wear them agents of erosion and weathering wear them down; younger sediment layers are deposited down; younger sediment layers are deposited horizontally on top of the eroded and tilted horizontally on top of the eroded and tilted layers. layers.

Draw into notes, pages 338 and 339, a, b, c and Draw into notes, pages 338 and 339, a, b, c and d.d.

• Disconformity (unconformity) Disconformity (unconformity) horizontal rock horizontal rock deposited, layers uplifted, exposed, and deposited, layers uplifted, exposed, and eroded. Younger rock is deposited horizontal, eroded. Younger rock is deposited horizontal, the gap that is missing. the gap that is missing.

Draw into notes, page 340, a, b, c.Draw into notes, page 340, a, b, c. NonconformityNonconformity occurs when sedimentary rock occurs when sedimentary rock

layers from above metamorphic intrusive layers from above metamorphic intrusive igneous rocks. The metamorphic or igneous igneous rocks. The metamorphic or igneous rock is lifted and eroded. Sedimentary rocks rock is lifted and eroded. Sedimentary rocks are then deposited on top of this erosional are then deposited on top of this erosional surface.surface.

Bell WorkBell Work

1.1. What is the principle of superposition?What is the principle of superposition?

2.2. ______________ is a technique that ______________ is a technique that determines the age of rocks as compared with determines the age of rocks as compared with one another.one another.

3.3. An unconformity between tilted and An unconformity between tilted and horizontal rock is a(n) _____________.horizontal rock is a(n) _____________.

4.4. A gap between horizontal rock layers is a(n) A gap between horizontal rock layers is a(n) _____________________._____________________.

Absolute Ages of RockAbsolute Ages of Rock

Objective 1: Identify how absolute dating differs Objective 1: Identify how absolute dating differs from relative dating.from relative dating.

Objective 2: Describe how the half-lives of Objective 2: Describe how the half-lives of isotopes are used to determine a rock’s age.isotopes are used to determine a rock’s age.

Absolute dating is a process that uses the Absolute dating is a process that uses the properties of atoms in rocks and other objects properties of atoms in rocks and other objects to determine their ages.to determine their ages.

Radioactive decay occurs when the number of Radioactive decay occurs when the number of protons in an atom changes.protons in an atom changes.

Half life of an isotope is the time it takes for half Half life of an isotope is the time it takes for half of the atoms in the isotope to decay.of the atoms in the isotope to decay.

Rediometric dating is done by knowing the Rediometric dating is done by knowing the parent and daughter materials in a rock and by parent and daughter materials in a rock and by knowing the half life of the parent. The knowing the half life of the parent. The absolute age of the rock can be calculate by absolute age of the rock can be calculate by the geologist. the geologist.

Radiocarbon dating Radiocarbon dating

Carbon-14 is useful for dating fossils, bones and Carbon-14 is useful for dating fossils, bones and wood up to 50 000 years.wood up to 50 000 years.

Principle of Uniformitarianism is a principle that Principle of Uniformitarianism is a principle that states that Earth processes occurring today are states that Earth processes occurring today are similar to those that occurred in the past. similar to those that occurred in the past. Theory by James Hutton, advanced by John Theory by James Hutton, advanced by John Playfair but most credit was given to Sir Playfair but most credit was given to Sir Charles Lyell.Charles Lyell.

Bell WorkBell Work1.1. Which method of dating determines the age Which method of dating determines the age

of a rock in years?of a rock in years?

2.2. What one of the daughter elements of What one of the daughter elements of uranium-238?uranium-238?

3.3. What is the time it takes for half of a What is the time it takes for half of a radioactive isotope to decay?radioactive isotope to decay?