PPT-The Geologic Time Scale Up to this point in Unit 1 we have talked about:

Formation of the Sun Planets and Earth Notes 1 How our planet was structured during formation Notes 2 Most recently we have discussed Earths history and the methods we use for putting together the story of our planet. How long ago were the dinosaurs here? How do we even describe geologic time anyway?. EONS. which are divided into . ERAS. ,. which are divided into. . PERIODS. ,. which are divided into. . EPOCHS. Chapter 7 lesson 4. What is the geologic time scale?. Geologists use the geologic time scale to show Earth’s history.. It is a record of the geologic events and the evolution of life forms as shown by the fossil record.. In depth: chapter 19. Geologic Time Scale. Examining layers of sedimentary rock, scientists have put together a chronology of Earth’s history.. It is divided into 4 Eras:. 1. Precambrian (3.5 . bya. 8. th. Grade Science. Geologic Time. Geologic time. . - Earth’s history is divided into units of time that make up the . Geologic . T. ime . S. cale. .. Time units on the scale are based on the appearance (. Who was James Hutton?. In the late 1700s, James Hutton began to question some of the ideas regarding the Earth.. He found fossils and saw them as evidence of life forms that no longer exist. . Different types of fossilized creatures were found in different layers of rock.. Geological “Clocks”. Geologic time determination is subdivided into 2 categories:. Relative Dating: simply determines whether or not an event occurs before or after another event (e.g. a granite dike is younger than the surrounding sandstone since it intrudes across the sandstone in an outcrop).. To learn how the geologic timeline was made and how the length of the various periods are different. Agenda. Progress reports – need to be signed by Parent/guardian. Geologic History Notes. Project –highlights. The geologic time scale divides Earth’s long history into units of time…. Eras. .  . Periods. .  . Epochs. Eras. are divided into . P. eriods. .. Periods. are divided into . Epochs. .. Precambrian. Section 12.1 Discovering earth’s history. Uniformitarianism – the idea that physical, chemical, and biological laws that operate today also operated in the past; the present is the key to the past.. a. Fossils. 3. Geologic Time Scale. 4. Geologic Belts. 5. NC Geologic History. How do we know . geologic . history. ?. Earth's History. Earth's history spans over a length of . 4.5 billion . years. Geologists have divided that time into units based on major geologic events and life forms. Using Content Analysis to Investigate the Treatment of Spatial and Temporal Scale in K-8 Science Standards and Textbooks Kim A. Cheek and Lauryn A. Stark Content Analysis Systematic coding and analysis of texts or visual material 99.9% of all living things that have ever existed on earth have gone extinct. earth has experienced 5 five extinctions . Geologic time scale. Era. Largest unit of geologic time . lasts tens to hundreds of millions of years and consists of two or more periods. . Normally we think of time in terms of days or years but geologists commonly refer to events that happened millions or billions of years ago. For example earth is approximately 4.6 billion years old. GEOLOGIC TIME. Absolute vs. Relative . Age. Relative Age. Determining the age of an object in relation to other objects. “Estimate”. Index Fossils, Rock layers. Example. : A friend tells you . he . has 2 brothers – one that’s older than .