Paleontology and Fossils images.usatoday.com/.../2006/11/07/fossil472.jpg

Uni-form-i-ta-rian-ism  In 1798, ____________, published the Theory of the Earth.  He said that the Earth’s geologic processes, that shaped the Earth, have been working together to continue reshaping the Earth.  This principle is called______________.

Ca-ta-stro-phism  _____________is the belief that all geologic change occurs suddenly.  These scientists believed that catastrophes (earthquakes, floods, hurricanes, etc.) caused the Earth to change.

Which Theory is Correct?  Scientists now believe that _______ processes shape the Earth!  It is believed that some catastrophes do change the Earth. For example, an Asteroid hit the Earth and caused extinction of Dinosaurs.

How Do Scientists Know about the Earth?  Studying layers of the Earth explains our history. (stratification!)  Scientists use 2 types of Dating:  ______________ is determining whether an object is older or younger than another by using____________.  ______________ is determining the _____age of an object by using a number of years.

Dating – A Measure of Time  Which statement describes Relative or Absolute age? 1.She is 12 years old. ______________ 2.She is my younger sister. _____________ 3.The 75 foot oak tree is older than the 12 foot oak tree. _________________. 4.The man is older than the teenager. _______________

 Write a short paragraph explaining why geologists use both absolute and relative dating to interpret the past.(pg st 2 paragraphs, pg st paragraph)  __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________

Relative Dating  Superposition is a principle that states younger rocks lie above older rocks.  “Law of Superposition”

Law of Superposition By applying this law scientists know that layer A is older than Layer C. Layer C is younger that Layer B. Which layer is the youngest? ______

Challenges  _______________ cause older layers to be pushed above younger layers and makes it hard to distinguish between older and younger.  They have used ___________ from all around the world to create a geologic column.

Geologic Column  The ______________is a ________ of ____________ that contains all the known fossils and rock formations on Earth arranged from _______to youngest.  View geologic column: The column The columnThe column

4 Disturbances  Natural forces are disturbances that cause changes in rock layers. (pg. 139)  All ____________are _______than the rock around them.  Faults  ___________  Folding  ________

Disturbances continued  Geologists use ________that __________ existing rock to help determine the rock’s ____________.  ______are breaks in the Earth’s crust where breaks______.  When molten rock squeezes into existing rock and cools it is called an_________.

Disturbances continued  _______occurs when rock layers bend and buckle from Earth’s internal forces.  _______occurs when internal forces slant rock layers without folding them.  _____________ are always _______than the rock layers that they affect.

Formation of Unconformities  When layers of rock are missing in sequence we call this____________.  ________and _____________have a lot to do with wearing away rock and causing unconformity.  Where does this rock go?

Types of Unconformities (pg. 141)  Unconformities link: Unconformities Unconformities  _____________– part of a parallel rock layer is missing. ___________.  _____________– sedimentary rock layers __________of eroded igneous or metamorphic rock.  ____________________– appears between horizontal layers that are ______ or_______.

Absolute Dating  To determine the __________ of rocks and fossil scientists use a process called _______________.  To do this they need to analyze radioactive isotopes.  ________are atoms of the same element that have the ___________ of _______ but different numbers of neutrons.

Isotopes  Most isotopes are stable.  Unstable ones are called___________.  Radioactive isotopes tend to __________ into stable isotopes over a period of time called ________________.  This _________happens at a ______pace and scientists use the relative amounts of stable and unstable isotopes to determine the object’s age.

How Does Radioactive Decay Work?  Link: Radiometric Dating Radiometric DatingRadiometric Dating  Determining the ratio of parent material to daughter material.  Link: Half-life Half-life  For every half-life, the parent material decreases by one-half.

Types of Radiometric Dating  ____________(has the longest half-life)  Potassium-40  __________(Used to determine the most accurate and precise age of the Earth)

Fossils ___________are preserved remains or traces of ____________. LLLLiving things die and are ______ by sediments. SSSSediments slowly harden into ___________ rock. AAAA ______________ is a scientist who studies fossils.

Types of Fossils  _________________– fossils found in tar, amber, or frozen. Even hair/teeth are preserved! Saber Tooth Cat!  _______________–______________all or part of an organism.  _____________ occurs to wood when water, rich in dissolved minerals, seeped into plant cells and then evaporated leaving hardened minerals behind.  ______ and ______ – Most_______. Copy of the shape of the organism.

Fossils Found in Rock Molds and casts

Fossils Found in Rock  ____________– thin film of carbon is left from a living organism. This can occur as an organism decays and gases are released, only carbon is left behind. Carbon film

Fossils Found in Rock  A ______is a hollow area in sediment in the shape of an organism or part of an organism.  A ____ is a copy of the shape of an organism. When an animal’s footprint ____ with ________ and _____ to rock.

Trace Fossils  _____________ are fossils that provide evidence of the activities of ancient organisms:  Footprints  Nests  Burrows – a shelter made by an animal that dug into the ground.

Change over time  Together, all of the information that paleontologists have gathered about past life is called the _____________.  The _____________ provides evidence about the _______________ on Earth.  The fossil record also shows that _________ groups of __________ have _______ over time.

Change over time  _____rocks contain fossils of _______ organisms while _______rocks contain fossils of ____________organisms.  __________is the gradual change in living things over long periods of time.

Geological Time Scale  How old is the Earth? Approximately ___ billion years old.  The time _____was developed by ______ rock ______ and ____________ worldwide.  Placed layers by ________ages, then used ________dating to refine the scale.

Geological Time Scale  Basic units of geologic time scale are:  Eons  _____  Periods  _____

Geological Time Scale  _____– the _______division of time.  Eras –______largest division.  _______– eras are divided into these  _______– periods are divided into these

Eons  Hadean eon – found __________and _____from the moon.  _______ eon – found ________know _____on Earth  Proterozioc eon –________________with well-developed cells appeared.

Eras  __________Era – first land-dwellers, plants and amphibians.  ________Era – Age of the_________  Cenozoic era – Age of________