#throwback ON EARTH’S PAST

1. #throwback ON EARTH’S PAST

2. GEOLOGIC EVENTS IN ROCK

3. in stratigraphy, paleontology and other natural sciences refers to the entirety of the layers of rock strata-deposits laid down in volcanism or by sediment deposition of weathering detritus (clays, sands etc.) including all its fossil content and the information it yields about the history of the Earth. GEOLOGIC RECORD The layer cake like appearance of concordant strata laid down over hundreds of thousands of years.

4. the rock column provides a cross section of the natural history in the area during the time covered by the age of the rocks. This is sometimes called the rock history and gives a window into the natural history of the location that spans many geological time units such as ages, epochs, or in some cases even multiple major geologic periods—for the particular geographic region or regions. CORRELATING THE RECORD Horseshoe Canyon Formations exposed in Horseshoe Canyon near Drumheller, Alberta

5. Correcting for discordancies can be done in a number of ways and utilizing a number of technologies or field research results from studies in other disciplines. DISCORDANT STRATA EX. Strata turned sideways by orogenic forces near San Sebastián, Spain

6. as the picture of the overall rock record emerged, and discontinuities and similarities in one place were cross-correlated to those in others, it became useful to subdivide the overall geologic record into a series of component sub-sections representing different sized groups of layers within known geologic time, from the shortest time span stage to the largest thickest strata eonothem and time spans eon. LITHOLOGY VS. PALEONTOLOGY

8. LIVING THINGS IN ROCKS * THE EVIDENCE OF FOSSILS * FOSSILS RECORD

9. Fossils record • Estimating dates - paleontology seeks to map out how life evolved across geologic time. A substantial hurdle is the difficulty of working out fossil ages. • Stratigraphy - is the science of deciphering the "layer-cake" that is the sedimentary record. • Limitations - Organisms are only rarely preserved as fossils in the best of circumstances, and only a fraction of such fossils have been discovered. • Lagerstatten - Fossil sites with exceptional preservation—sometimes including preserved soft tissues • Stromatolites - layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria.

10. THE EARTH’S CLIMATE

11. Life on Earth has flourished and evolved for hundreds of millions of years.  However, this does not mean that the climate has been stable throughout this time. Geological data shows evidence of large-scale climate changes in the past, caused by factors like the tilt of the Earth’s axis and tectonic plate movement (as climate is affected by the distribution of the planet’s continents). Some of these changes were gradual; others were much more rapid. Cretaceous world In the mid Cretaceous, about 100 million years ago, the distribution of fossil plants, and large herbivorous dinosaurs, suggests sub-tropical conditions extended to Alaska and Antarctica and there were no polar ice caps.  The planet was warmer than today - scientists have estimated it was 6 – 8°C warmer. Carbon dioxide levels in the atmosphere were about 5 times higher than today. These warm conditions lasted for tens of million of years before the climate started cooling.

12. The ice ages In the recent geological past, much of Britain was covered by ice sheets. We know this because the landscape shows many distinctive glacial landforms, especially in North Wales, Scotland and the Lake District. Also, fossils of mammoths and woolly rhinoceroses, which lived in cold climates, have been found across southern Britain. This type of evidence, along with marine sediment cores and ice cores, shows that over the past 2 million years, climate fluctuated dramatically between ice ages and warm interglacial periods, similar to today’s climate. These major changes were driven by cyclical changes in the Earth’s orbit, which altered the distribution of solar energy between the seasons and across the Earth. An inescapable conclusion of this is that the Earth’s climate is unstable and minor changes in the Earth's energy budget cause large changes in climate.

13. * Sea level rising * Global Temperature Rising * Shrinking ice sheets The evidence for rapid climate change nowadays: * Ocean acidification

14. The shape of the Earth's orbit around the sun naturally changes over time, and so does the way the Earth tilts toward the sun. Many of these changes happen in cycles that repeat over tens of thousands of years. These changes affect how much of the sun's energy the Earth absorbs, which in turn affects the Earth's temperature. Over at least the last few million years, these cycles likely caused the Earth to alternate between cold and warm periods. For the last few thousand years, we've been in a relatively warmer period.

15. The sun goes through sunspot cycles every 11 years or so. During times when there are sunspots, dark spots—some as big as 50,000 miles wide—move across the surface of the sun. When this happens, the sun gives off slightly more energy, which makes the Earth a bit warmer. The sun also goes through longer term changes that affect how much energy it gives off.

16. The Earth's first billion years were very different from the conditions today. The sun was cooler then, but the planet was generally warmer. That's because there were a lot of greenhouse gases, like carbon dioxide and methane, in the atmosphere. Also, the atmosphere back then contained very little oxygen. It was a very different world—a world without people or the kinds of plants and animals that thrive in today's climate. But photosynthesis, which became common about 2 billion years ago, changed all that. During photosynthesis, plants take carbon dioxide out of the atmosphere and replace it with oxygen. Photosynthesis permanently changed the atmosphere by adding more oxygen to the air while reducing the amount of greenhouse gases.

17. When volcanoes erupt, they spew more than red hot lava! They also add carbon dioxide to the atmosphere, along with dust, ash, and other particles called aerosols. At certain times during the history of the Earth, some very active volcanoes added a lot of carbon dioxide to the atmosphere, causing the planet to get warmer. However, most of the time, including today, the major effect from volcanoes is actually cooling the Earth because aerosols block some sunlight from reaching us. If an eruption is big enough to launch these particles high into the atmosphere, it can lead to slightly cooler temperatures around the world for a few years.

18. * Changes in the Earth’s orbit * Changes in the Sun Energy * Photosynthesis some natural factors that have changed the Earth's climate in the past. * Volcanic Eruptions 8

19. Sea level rising Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.

20. Global temperature rises All three major global surface temperature reconstructions show that Earth has warmed since 1880.Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years. Even though the 2000s witnessed a solar output decline resulting in an unusually deep solar minimum in 2007-2009, surface temperatures continue to increase.

21. Warming oceans The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees Fahrenheit since 1969.

22. Shrinking ice sheets The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005.

23. Ocean acidification Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30 percent.This increase is the result of humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by about 2 billion tons per year.

24. AGE OF THE EARTH

25. the history of the earth based on life-forms that have existed during specific times since the creation of the planet Most of these life-forms are found as fossils, which are the remains or traces of an organism from the geologic past that has been preserved in sediment or rock. Without fossils, scientists may not have concluded that the earth has a history that long precedes mankind Geologic Time

26. It has 8periods: *Protezoic*Cambrian*Ordovician *Silurian*Devonian*Mississippinian *Pennsylvinian*Permian*Triassic *Jurassic*Cretaceous*Tertiary *Quarternary Geologic Time

27. Proterozoic No life possible as the Earth initially forms 4.6 billion years ago. Simple, single-celled forms of life appear 3.8 billion years ago, becoming more complex and successful over the next 3 billion years: Prokaryotes then Eukaryotes Cyanobacteria begins producing free oxygen (photosynthesis) Land masses gather to make up a continent called “Rodinia”

28. CAMBRIAN Explosion of life Life forms in warm seas as oxygen levels rise enough to support life Dominant animals: Marine invertebrates (trilobites and brachiopods) Supercontinent Gondwana forms near the South Pole (note position of present-day Florida)

29. ordoviciAn The 1st animals with bones appear, though dominant animals are still trilobites, brachiopods and corals The beginning of the construction of South Carolina A very cold time in Earth’s history: there was a great extinction due to ice caps in present-day Africa Four main continents: Gondwana, Baltica, Siberia and Laurentia

30. SILURIAN First land plants appear and land animals follow Laurentia collides with Baltica and closes Iapetus Sea. Coral reefs expand and land plants begin to colonize barren land. First millipede fossils and sea scorpions (Euryptides) found in this period

31. DEVONIAN Pre-Pangea forms. Dominant animal: fish Oceans still freshwater and fish migrate from southern hemisphere to North America. Present-day Arctic Canada was at the equator and hardwoods began to grow. Amphibians, evergreens and ferns appear The Acadian Orogeny, leading to S.C. metamorphism

32. MISSISSIPPIAN First seed plants appear Much of North America is covered by shallow seas and sea life flourishes (bryoza, brachipods, blastoids)

33. pennsylvanian Modern North America begins to form Ice covers the southern hemisphere and coal swamps formed along equator. Lizards and winged insects first appear.

34. permian Last period of the Paleozoic Pangea forms. Reptiles spread across continents. The Appalachians rise 90% of Earth’s species become extinct due to volcanism in Siberia. This marks the end of trilobites, ammonoids, blastoids, and most fish.

35. triassic First dinosaurs appear First mammals- small rodents appear Life and fauna re-diversify Rocky Mountains form. First turtle fossil from this period Pangea breaks apart

36. JURassic Pangea still breaking apart Dinosaurs flourish “Golden age of dinosaurs” First birds appear North America continues to rotate away from Africa

37. cretaceous T-Rex develops First snakes and primates appear Deciduous trees and grasses common First flowering plants Mass extinction marks the end of the Mesozoic Era, with the demise of dinoaurs and 25% of all marine life.

38. tertiary First horses appear and tropical plants dominate (Paleocene) Grasses spread and whales, rhinos, elephants and other large mammals develop. Sea level rises and limestone deposits form in S.C. (Eocene) Dogs, cats, and apes appear (Oligocene) Horses, mastadons, camels, and tigers roam free in S.C. (Miocene) Hominids develop and the Grand Canyon forms (Pliocene)

39. quaternary Modern humans develop and ice sheets are predominant- Ice age (Pleistocene) Holocene Humans flourish (Holocene)

40. electron nucleus proton neutron RADIOACTIVE MATERIALS

41. An atom of an element with a different number of neutrons is an isotope of that element. Some isotopes are radioactive, which means they are unstable and likely to decay. This means the atom will spontaneously change from an unstable form to a stable form. Rate of Radioactive Decay Radioisotopes decay at a constant rate. Rate of decay is measured by half-life Half-life -- time it takes for one-half of the radioactive material to decay. Decay products Radioisotopes may decay to form a different isotope or a stable isotope. May be a series of radioactive decays before a stable isotope is formed. Stable isotope is called the "daughter" formed from decay of radioactive "parent"

42. How old is old? Charles Lyell tried to estimate the age of the earth through the amount of evolution exhibited by marine mollusks in a specific time system. Another method was to estimate the rate of deposition for sedimentary rocks. Sir Edmund Halley proposed to estimate the age of the earth using salt content of the oceans, assuming that the oceans were once non-saline and that salt addition to the oceans corresponded in some linear fashion with time. Lord Kelvin estimated the age of the Earth at 24-40 million years. He proposed that the Earth has been cooling since it formed, and he calculated the rate of cooling using principles of heat conduction.

43. How old is old? The oldest rocks found so far on Earth (based on zircon grains from Australia) have been dated at 4.1-4.2 billion years. The oldest fossils are preserved remains of stromatolites, which are layers of lithified blue-green algae, dating to approximately 3.5 billion years before present. Meteorites have also been dated at 4.6 billion years. Meteorites are considered to be remnants of a plant or asteroid that originally formed at the same time as the Earth, so that the Earth’s age is currently estimated to be 4.6 billion years.

44. CHANGES UNDERGONE BY CONTINENTS

45. Reshaping Earth’s Crust • rifting the process by which Earth’s crust breaks apart; can occur within continental crust or oceanic crust • Slow movements of tectonic plates change the size and shape of the continents over millions of years. • All of the continents that exist today contain large areas of stable rock, called cratons, that are older than 540 million years. Rocks within the cratons that have been exposed at Earth’s surface are called shields. • One way that continents change shape is by breaking apart. Rifting is the process by which a continent breaks apart.

46. Reshaping Earth’s Crust, continued • terranea piece of lithosphere that has a unique geologic history and that may be part of a larger piece of lithosphere, such as a continent • Continents change not only by breaking apart but also by gaining material. Most continents consist of cratons surrounded by a patchwork of terranes. • Terranes become part of a continent at convergent boundaries. When a tectonic plate carrying a terranesubducts under a plate made of continental lithosphere, the terrane is scraped off of the subducting plate and becomes part of the continent.

47. THE EVIDENCE OF FOSSILS

48. Fossils

49. What is a fossil? A fossil is an impression, cast, original material or track of any animal or plant that is preserved in rock after the original organic material is transformed or removed.

50. A fossil may be: • an original skeleton or shell; • a mold or cast; • material that has replaced the once living thing; • traces such as footprints or worm tubes