Science Olympiad Fossils Division B 2015 3- Geological Time & Index Fossils

1. Science OlympiadFossilsDivision B20153- Geological Time & Index Fossils

2. Geological Time • The ages of geological Time

3. Geologic time scale http://www.geosociety.org/science/timescale/timescl.pdf

4. Geological Time The basic unit of geologic time is 1 ,000,000 (one million) years. A million is an incredible number. To better understand how long one million years is, we can convert it to some more familiar unit of measure. If we let one inch equal one thousand years, then one million years would equal 83.3 feet. One hundred years (longer than the average life span) would be represented by just one tenth (1/10 or 0.1) of an inch. If one goes back to the beginning of the Cambrian Period, some 570,000,000 years ago - one would need almost 9 miles to represent this part of the Earth history. To map out all of geologic time, one would need more than 72 miles. The lowest layers formed first and are the oldest. As you progress up a column of rocks you progress through younger and younger layers. Early geologists used fossils as markers to correlate and thereby determine the relative ages of rocks. This led to the ability to construct a geologic column made up of rocks of different ages from different locations. • Written, compiled and illustrated by Midwest Mineralogical and Lapidary Society of Dearborn, Michigan

5. Geological Time The geologic history of the Earth is broken up into hierarchical chunks of time. From largest to smallest, this hierarchy includes eons, eras, periods, epochs, and ages. From Wed site: http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/gtpage6.html These time intervals are not equal in length like the hours in a day. Instead the time intervals are variable in length. This is because geologic time is divided using significant events in the history of the Earth. Examples of Boundary "Events“ For example, the boundary between the Permian and Triassic is marked by a global extinction in which a large percentage of Earth's plant and animal species were eliminated. Another example is the boundary between the Precambrian and the Paleozoic which is marked by the first appearance of animals with hard parts. From Web site: http://geology.com/time.htm

6. Geological Time Eons - Are the largest intervals of geologic time and are hundreds of millions of years in duration. In the time scale above you can see the Phanerozoic Eon is the most recent eon and began more than 500 million years ago. Eras - Eons are divided into smaller time intervals known as eras. In the time scale above you can see that the Phanerozoic is divided into three eras: Cenozoic, Mesozoic and Paleozoic. Very significant events in Earth's history are used to determine the boundaries of the eras. Periods - Eras are subdivided into periods. The events that bound the periods are wide-spread in their extent but are not as significant as those which bound the eras. In the time scale above you can see that the Paleozoic is subdivided into the Permian, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician and Cambrian periods. Epochs - Finer subdivisions of time are possible and the periods of the Cenozoic are frequently subdivided into epochs. Subdivision of periods into epochs can be done only for the most recent portion of the geologic time scale. This is because older rocks have been buried deeply, intensely deformed and severely modified by long-term earth processes. As a result, the history contained within these rocks can not be as clearly interpreted. Ages – is the smallest subdivision From Web site: http://geology.com/time.htm

7. Geological Time • ThePhanerozoic Eon represents the time during which the majority of macroscopic organisms — algae, fungi, plants and animals — lived. When first proposed as a division of geologic time, the beginning of the Phanerozoic (542.0 million years ago)* was thought to coincide with the beginning of life. In reality, this eon coincides with the appearance of animals that evolved external skeletons, like shells, and the somewhat later animals that formed internal skeletons, such as the bony elements of vertebrates. The time before the Phanerozoic is usually referred to as the Precambrian and is usually divided into the three eons. • From Wed site: http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/gtpage6.html

8. Geological Time • The Phanerozoic is subdivided into three major divisions: the Cenozoic, Mesozoic, and Paleozoic Eras. The "-zoic" suffix comes from the root "zoo," which means animal.. "Cen-" means recent, "Meso-" means middle, and "Paleo-" means ancient. These divisions reflect major changes in the composition of ancient faunas, each era being recognized by its domination by a particular group of animals. The Cenozoic has sometimes been called the "Age of Mammals," the Mesozoic the "Age of Dinosaurs," and the Paleozoic the "Age of Fishes." But this is an overly simplified view, which has some value for the newcomer but can be a bit misleading. For instance, other groups of animals lived during the Mesozoic. In addition to the dinosaurs, animals such as mammals, turtles, crocodiles, frogs, and countless varieties of insects also lived on land. Additionally, there were many kinds of plants living in the past that no longer live today. Ancient floras went through great changes too, and not always at the same times that the animal groups changed. • From Wed site: http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/gtpage6.html

9. Ages of Geological Time Era Period or Epoch Age  Cenozoic Pleistocene Age of Man Pliocene Miocene Oligocene Age of Mammals Eocene Paleocene Mesozoic Cretaceous Jurassic Age of Reptiles Triassic  Paleozoic Permian Carboniferous Age of Amphibians Devonian Silurian Age of Fishes Ordovician Cambrian Age of Sea Life

10. An Example of the Law Super position Picture from Web Site: http://www.t-rat.com/Pages/WhereToFindFossils.html

11. This example correlates formations throughout a large region in the southwestern part of the United States noted for its spectacular scenery. The composite section can be thought of as representing a large, although incomplete, segment of relative geologic time. A global time scale has been derived by extending the correlations from one place to another and reaching from one continent to another. These correlations are based in large part on fossil evidence. Return to Relative Time Scale

12. Relative Dating • Relative dating orders events in chronological order. It tells you which events came first, but it does not tell you the exact date of which it occurred. There are different methods that are used for relative dating. They are the principle of superposition, the principle of original horizontality, the principle of cross-cutting relationships, and the principle of inclusions. • Principle of Superposition: If you have undisturbed layers of sedimentary rocks, than the layers will be younger as they near the top. The oldest layers are on the bottom and the tallest layers are on the top. • Principle of Original Horizontality: Rocks are originally layered horizontally. If you have layers that are higher on one side than on the other, it is due to the tilting of rocks caused by a geological event. • Principle of Cross-Cutting Relationships: This principle states that a fracture or cut in a rock caused by another rock (igneous intrusion) is always younger than the rock it cuts. • Principle of Inclusions: Fragments of one rock in another rock must be older than the rock it is contained in. From Web site: http://scioly.org/wiki/index.php/Fossil

13. Absolute Dating • Absolute dating is similar to relative dating in that they both order events in chronological order. However, unlike relative dating, absolute dating can determine the ages of rocks. There are several methods that are used in absolute dating, including radiometric dating, half-life, and carbon dating. • Half-life: The half-life of an isotope is how much time it takes for half the atoms in that isotope to decay. After that many years, half the atoms in the isotope will decay. After that many years again, half of that half (one quarter of the whole or two half-lives) will decay. After that many years again, half of the half of that half (one eighth of the whole or three half-lives) will decay. It will go on until the isotope decays to its daughter product. • Major radioactive isotopes and their half-life: - Carbon 14 5730 years - Potassium 40 1.25 Ga years - Uranium 235 703.8 Ma - Uranium 238 4.468 Ga - Thorium 232 14.05 Ga - Rubidium 87 48.8 Ga - Samarium 147 106 Ga Ma = Million Years Ga = Billion Years • From Web site: http://scioly.org/wiki/index.php/Fossil

14. NEW GEOLOGICAL PERIOD ADDED

15. NEW GEOLOGICAL PERIOD ADDED On May 13, 2004, the International Union of Geological Sciences (IUGS) announced the first new geological period declared in 120 years—the Ediacaran Period. The IUGS is an international non-governmental organization devoted to international cooperation in the field of geology. One of its daughter groups, the International Commission on Stratigraphy, is the generally accepted authority on the names and starting/ending dates of the various subdivision of the geological time scale. The Ediacaran Period takes its name from the Ediacara Hills, located in the Flinders Ranges of South Australia, the location of the type site or Global Boundary Stratification and Selection Point (GSSP). The Ediacaran is the last geological period of the Neoproterozoic Era, just preceding the Cambrian Period of the Paleozoic Era. Its assigned time range is 635 to 542 million years ago. Since animals with hard shells (exoskeletons) did not appear until the Cambrian Period, the fossil record for the new period is sparse. However, the Ediacaran biota include the oldest definite multicellular organisms with tissues, the most common types resembling segmented worms, fronds, disks, or immobile bags. They bear little resemblance to modern lifeforms, and their relationship even with the later lifeforms of the Cambrian explosion is difficult to interpret. More than 100 genera have been described, and well known forms include Arkarua, Charnia, Dickinsonia, Ediacaria, Marywadea, Onega, Pteridinium, and Yorgia.

16. NEW GEOLOGICAL PERIOD ADDED Although the Ediacaran Period does contain soft bodied fossils, it is unusual in comparison to later periods because its beginning is not defined by a change in the fossil record. Rather, the beginning is defined at the base of a chemically distinctive carbonate (a salt or ester of carbonic acid) layer, referred to as a "cap carbonate," because it caps glacial deposits and indicates a sudden climatic change at the end of an ice age. This bed is characterized by an unusual depletion of C-13, and is considered by many scientists to be of global extent.

17. Geological Time Review file on CD: Fossils-2002.pps

18. Questions ?

19. Next Week’s Topics? • Practice Tests/ Game

20. Flash Cards Instructions • Divide the work between team members • Check each others work • Work on the fossils assign to your team • Use the sample flash cards posted to the schools Science Olympiad web site under the Fossil event. Sample Files are: • FlashCardsFusulinidsNummulites.ppt • FlashCardsHemichordataMucrospirifer.pptx • Save your flash card files using this name: • FlashCardsNameof FossileName of Fossil • Example is: FlashCardsFusulinidsNummulites.ppt • For Fossil pictures start with these 3 files loaded on the school Science Olympiad web site • 2009-Fossil-Poster.pdf • 2009-Fossil-Notes-B.pdf • 2009-Fossil-Notes-B2.pdf • Another good source is: • Web Site: http://scioly.org/wiki/index.php/Fossil_List