Fossils evidence of past life Remains or traces of prehistoric life click here for 9 page to print Petrified Cavities and pores are filled with precipitated p p mineral matter Petrified Formed by replacement Cell material is removed and replaced with mineral matter Mold Shell or other structure is buried and then dissolved by underground water http www ammonoid com Manning html http www ammonoid com Manning html Shape is preserved in the surrounding sediment Cast Hollow space of a mold is filled with mineral matter Carbonization Organic matter becomes a thin residue of carbon This is a compression of the original organism Impression Replica of the fossil s surface preserved in fine grained sediment http www lfbuffalo org exhibitions map t Preservation in amber Hardened resin of ancient trees surrounds an organism Indirect Evidence Includes Tracks Burrows Coprolites C lit fossil dung g and stomach contents Gastroliths stomach stones used to grind food by some extinct reptiles Tracks Dinosaur footprint in fine grained limestone near Tuba City Arizona Types of fossils Petrified Formed by replacement l t Mold Cast Carbonization Impression Preservation in amber Indirect evidence Conditions favoring preservation Rapid burial Possession of hard parts Fossils and correlation Principle P i i l off ffaunall succession i Index fossils Principle of faunal succession http www lfbuffalo org exhibitions map a Proposed p by y William Smith late 1700s Fossil organisms succeed one another in a definite and determinable order order therefore any geologic time interval can be recognized by its fossil content Archean through Devonian http rst gsfc nasa gov Sect2 Sect2 1b html Carboniferous through Quaternary http rst gsfc nasa gov Sect2 Sect2 1b html Cambrian Marine Life http www handprint com PS GEO geoevo html Trilobite http www ststephens it biology fossils html Ordovician Invertebrates http www handprint com PS GEO geoevo html Crinoid 380 ma Crinoid 380 http www lsa umich edu exhibitmuseum exhibits temporary exhibits Ordovician sea floor http www uwsp edu geo faculty hefferan Geol106 CLASS6 MAIN 20PAGE htm Silurian reef Silurian Reef http hoopermuseum earthsci carleton ca camex 1rpaleoreef html Silurian Landscape http www nasa gov worldbook earth worldbook html Devonian Sea http www handprint com PS GEO geoevo html Mid Paleozoic http www tufts edu as wright center cosmic evolution docs text text bio 4 html Late Paleozoic http www tufts edu as wright center cosmic evolution docs text text bio 4 html Carboniferous Fern Forests http www handprint com PS GEO geoevo html Permian Sea http www handprint com PS GEO geoevo html Permian Reptiles http www handprint com PS GEO geoevo html Permian Extinction Link to hypotheses of the Permian Extinction http en wikipedia org wiki Permian p p g extinction 80 95 of marine species died out 70 70 off tterrestrial t i l vertebrates t b t Largest a gest e extinction t ct o ep episode sode in geo geologic og c record Geologic time scale Divides geologic history into units Originally created using changes in organisms representing that time interval Subdivisions Eons E Eras Eras Periods Epochs Eon Greatest expanse of time 4 eons Phanerozoic a e o o c visible s b e life e the e most recent eon started 543 Ma Proterozoic 2500 543 Ma Archean A h 3800 2500 M Ma Hadean oldest eon 4500 4500 3800 3800 Ma Eras of the Phanerozoic eon Cenozoic recent life 65 Ma now Mesozoic middle life 248 65 Ma Paleozoic ancient life 543 248 Ma Geologic Time Scale Mesozoic http geography berkeley edu ProgramCourses CoursePagesFA2002 Geog40 Geog40 Week7 html Mesozoic http serc carleton edu introgeo earthhistory dinosaur html Mesozoic http geography berkeley edu ProgramCourses CoursePagesFA2002 Geog40 Geog40 Week7 html Mesozoic http www tufts edu as wright center cosmic evolution docs text text bio 4 html A h Archeopteryx t http www researchcasting ca sculpt 20miami htm Mesozoic Mammal Eomaia http www amnh org exhibitions dinosaurs diorama Mesozoic Mammal Repenomamus http www amnh org science papers mesozoic mammal php Jurassic http www worldbook com features dinosaurs html world mesozoic html Cretaceous http www worldbook com features dinosaurs html world mesozoic html Mesozoic Sea http geography berkeley edu ProgramCourses CoursePagesFA2002 Geog40 Geog40 Week7 html Mesozoic sea http www uky edu AS Geology webdogs time mesozoic mesozoic htm Cretaceous Extinction Perhaps 60 of species died Result of radical change in environment Perhaps Earth encountered a large meteorite t it 10 km in diameter 90 000 km hr Equivalent to 100 megatons of TNT exploding Cenozoic mammals http www handprint com PS GEO geoevo html Cenozoic http www handprint com PS GEO geoevo html Cenozoic http www uky edu AS Geology webdogs time cenozoic cenozoic htm Cenozoic http www copyrightexpired com Heinrich Harder cenozoic html Relative dating Placing Pl i rocks k and d events t iin proper sequence of formation Deciphering Earth s history from clues in the rocks Lateral Continuity http cse cosm sc edu hses RelatDat pages lateral htm Principle of Original Horizontality Sediment is deposited p horizontally http faculty icc edu easc111lab labs labf orig horizontality jpg P i i l off Superposition Principle S iti Oldest rock A Younger rocks above E is i th the youngest http cse cosm sc edu hses RelatDat pages superpos htm Principle of Cross cutting Relationships Younger feature cuts through an older feature Something must exist first to be cut by another thing The things cutting may be things such as igneous i iintrusions t i Or they y may y be events like fault breaks folding or erosion periods Cross cutting g relationships Folding occurred after deposition http rst gsfc nasa gov Sect2 Sect2 6 html Unconformities A break in the rock record Three types of unconformities Angular unconformity Disconformity strata on either side are parallel Nonconformity Angular Unconformity Tilted rocks are overlain by flat lying rocks Remember the principle of original horizontality Formation of an ang lar angular unconformity Simple angular unconformity http www grisda org colorado index htm Folding erosion Folding erosion deposition deposition folding http rst gsfc nasa gov Sect2 Sect2 6 html Nonconformity Metamorphic or igneous rocks below Younger sedimentary rocks above Nonconformity Disconformity Gap in sedimentation that may have erosion also Represents an interval in geologic time without rock deposited Most difficult of the three
View Full Document
Unlocking...