which mass extinction event was the biggest, resulting in biggest loss of biodiversity?GEOL 1301 Fall 2014Mini Exam # 2 Study Guide (September 30th – October 7th)Chapter 8 Clocks in Rocks: Geological Time The geologic time scale (GTS) is a system of chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists, and other earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history. The table of geologic time spans presented here agrees with the nomenclature, dates and standardcolor codes set forth by the International Commission on Stratigraphy.Evidence from radiometric dating indicates that the Earth is about 4.54 billion years old. The geology or deep time of Earth's past has been organized into various units according to events which took place in each period. Different spans of time on the GTS are usually delimited by changes in the composition of strata which correspond to them, indicating major geological or paleontologicalevents, such as mass extinctions. For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the dinosaurs and many other groups of life. Older time spans which predate the reliable fossil record (before the Proterozoic Eon) are defined by the absolute age.KEY TERMS AND CONCEPTSabsolute agebased on radioactivity, measured in Ma. The number of years elapsed from that event until now; before the 20th century, no one knew much about __relative agesbefore the 20th century, geologists could determine only whether one event was earlier or later than another, their __4.28 billionEarth's oldest known rocks formed about __ years agostratiographythe study of 'sedimentary' strata (layers) in rocks.stratalayers in rocksprinciple of original horizontalitythe __ states that sediments are deposited under the influence of gravity as nearly horizontal bedsprinciple of superpositionthe __ states that each layer of an undeformed sedimentary sequence is younger than the one beneathit and older than the one above ithorizontallysediments are deposited __ due to the force of gravityunconformityboundary along which the two existing formations meetand there is a gap in the rock record. (ABCE) comparedto (ABCD)disconformity-caused by tectonic uplifts and sea level drops.-an upper sedimentary sequence overlies an erosional surface developed on an undeformed, still-horizontal lower sedimentary sequence is a __nonconformityin a __, the upper sedimentary beds overlie metamorphic or igneous rocksangular unconformityan __ is one in which the upper beds overlie lower beds that have been folded or compressed by tectonic processes and then eroded to a more or less even planeeons, eras, periods, epochsthe (4) intervals of geologic time, from most broad to most specificmass extinctionsmany of the major boundaries in the geologic time scale represent __: short intervals during which a large proportion of the species living at the time simply disappeared from the fossil record, followed by the blossoming of many new speciesisotopic datingthe use of naturally occurring radioactive elements to determine the ages of rocksparent, daughterwhen discussing radioactive isotopes, we call the original atom the __ atom and the product of decay its __half-lifethe rate of radioactive decay is measured by the isotope's __, the time required for 1/2 of the original number of parent atoms to be transformed into daughter atomscannotthe relative age of the granite (can/cannot) be calculated knowing the half-life of uranium-238 is 4.5 million yearsPhanerozoicin which eon did humans evolve6543 Ma-todayfossil record, Cambrian explosionmetamorphic, sedimentarya nonconformity erosional surface is typically located where __ rocks are underneath __ rocksstratigraphic successiona chronologically ordered set of stratafaunal successionFossil species succeed each other in a definite and recognizable order. Stratigraphic ordering of the fossilsof animal species in sedimentsoutcropRock or layers of rock that are exposed and visible at the earth's surface.cross cuttingintrusions that cut through rock layers and are younger1faultsa crack in the earth's crust resulting from the displacement of one side with respect to the other. Cross cutting relationship, displace and shift blocks of rock.dikescross cutting through sedimentary bedssillscross cutting parallel to bedding planesSteno Principlesprincipal of original horizontality, principle of superpositionSmiths Principlesprinciple of faunal successionUranium, Potassium, Rubidium, CarbonRadioactive elements used in radiometric/isotopic datingHadean4.6-4.0 Ga hellish eon, very volcanic, molten surfaceArchean4.0-2.5 GaMetamorphic deep water sediments, early life, moon bombardmentProtozeroic2.5 Ga - 543 MaPhotosynthesis puts oxygen in the atmospherebanded iron formations and greenstone beltsOzone layer developsMajor Earth glaciations (Snowball Earth)Greenstone beltssource of economically important mineralssequence of ig., met., and sed. rocksassociated with continent formationPaleozoic EraOldest era of Phanerozoic eon. 542-251 MaMesozoicMiddle era of Phanerozoic eon. 251-65M Ma251 MaWhen was the mother of all extinctions that lasted 600,000 to 1 my665.5 MaWhen was the bolide impact that terminated dinosaurs and ammonites6Based on el kef in Tunisia(October 9th – October 14th)Chapter 11 GeobiologyBroadly defined, geobiology is an interdisciplinary field of scientificresearch that explores interactions between the biosphere and thelithosphere and/or the atmosphere.Major geobiological eventsPerhaps the most profound geobiological event is the introduction of oxygen into the atmosphere by photosynthetic bacteria. This oxygenation of Earth's primoidial atmosphere (the so-called oxygen catastrophe) resulted in the precipitation of banded-iron rock formations.A subsequent major change was the establishment of terrestrial plant life, which affected continental erosion and changed the types of rivers observed, allowing channelization of what were previously predominantly braided rivers.More subtle geobiological events include the role of termites in overturning sediments, coral reefs in depositing calcium carbonate and breaking waves, sponges in absorbing dissolved marine silica, the role of dinosaurs in breaching river levees and promoting flooding, and the role of large