PPT-The Geologic Time Scale Mass extinctions

999 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 . Mass extinctions are global events characterized by unusually high rates of extinction The magnitude of these rates is usu ally unspecified but it is generally significantly higher than the rate of so called background extinctions that is extinc tio The struggle for life on earth. Mass Extinction - Definition. A significant proportion of species become extinct (between 30% and 95%) . The extinctions operate across a wide range of environments and . 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.. Very general images. What is with the . zig. . zag. ? . Has the earth cooling-shows really deep time!. Shows Cambrian Explosion period.. Mentions algae and eukaryotic cells.. Has all groups! Nice sense of how things evolved. Not straight hard to follow. Hard to tell . 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 (. 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. Opportunities and. Adaptive Radiations. Overview. Extinctions. Adaptive Radiations—New Niches. Stem mammals survived and experience adaptive radiation.. Evolution of birds, feathers, flight, and flightlessness.. 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. 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. Extinction . When an organism is classed as extinct there are no living members of that species left. Extinction is a natural process where organisms that are less suited to an environment die out. Throughout the history of earth there have been several mass extinction events .