Upcoming SlideShare
Loading in...5
×
 

Op ch13 lecture_earth3, Understanding of Earth history,

on

  • 363 views

Understanding of Earth history, ...

Understanding of Earth history,
The Earth is the stage on which the evolutionary play is performed. Darwin studied evolution in the context of Charles Lyell's geology, but our present understanding of Earth history includes some critical advances made during the last half-century.

Statistics

Views

Total Views
363
Views on SlideShare
363
Embed Views
0

Actions

Likes
1
Downloads
15
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Op ch13 lecture_earth3, Understanding of Earth history, Op ch13 lecture_earth3, Understanding of Earth history, Presentation Transcript

  • Earth: Portrait of a Planet 3rd Edition Chapter 13 Norton Media Library
  • AB Prepared by Ronald Parker Earlham College Department of Geosciences Richmond, Indiana iogr a phy of E arth
  • Earth Has a History Geologic materials record enormous changes.  Earth is a complex, evolving system.  Physical and biological systems continuously interact.  Earth constantly changes and has done so through time.  Species arise, flourish and disappear forever. Continents rift, drift and collide. Ocean basins open and close. Sea-level rises and falls. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Historic Earth changes are measured by… Orogenic events.  Sea level.  Climates.  Living organisms.  Continental positions.  Plate boundaries.  Chemistry.  Atmosphere. Ocean.   Depositional environments. These changes are recorded in rocks. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Earth history is not always easy to decipher.  Much of the record of past events is incomplete. Why? The record didn’t accumulate continuously. Erosion destroys the record with age as a variable. Younger rocks are better preserved; older rocks less so. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Earth history is not always easy to decipher. Despite erosion, there is still an abundance of evidence.  This evidence is often readily observed by looking at rocks.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Ancient orogens – Former mountain belts. Igneous activity, deformation and metamorphism.  Thick sedimentary deposits filling foreland basins.  Ancient orogenic belts expose deeply buried rocks.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Clear evidence of continental growth over time.  Continents grow by addition along edges. Continental interiors are older. Rocks become younger toward margins. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Recognizing depositional environments.   Successions of strata record changes in depositional settings. Recognizing sea-level changes. Sediments record sea-level flux.  Shallow and deep environments create distinctive sediments.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Changing continental positions are preserved. Paleomagnetism captures paleolatitude.  Ocean width changes by reversing sea-floor anomalies.  Rock and fossil distributions compare across oceans.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Paleoclimates – Rocks preserve ancient climates. Tropical – Extensive coral reefs.  Sub-tropical – Extensive deserts.  Polar – Extensive glacial deposits.   Climatic belts expand and contract. Greenhouse Earth.  Snowball earth.   O/16O isotopic ratios preserve ancient temperatures 18 Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Methods for Studying the Past  Evolution – Fossils preserve changes in Earth’s life. Sedimentary rocks preserve fossil ecosystems.  Organisms inhabiting Earth have obviously changed.  Over geologic time, most species have exhibited both… Trends toward specialization. Catastrophic extinctions. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Hadean Eon  Geochronology dates the age of Earth to 4.57 Ga.  Based on ages of meteorites akin to planetesimals. Continental crustal rocks date from 3.8 Ga.  The time between 4.57 – 3.8 Ga is the Hadean Eon.  Named for Hades, the Greek god of the underworld.  Began with formation of Earth by planetesimal accretion.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Hadean Eon Earth was heated by impacts and radioactive decay.  Earth was hot enough to partially melt by ~ 4.5 Ga.   The molten Earth underwent chemical differentiation. Gravity pulled molten iron into the center. The ultramafic mantle remained as a thick shell. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Hadean Eon After differentiation, Earth smashed a proto-planet.  The size of Mars, this planet blasted…  A sizeable chunk of Earth’s mantle.  Much of the proto-planet’s mantle.   Debris from the collision formed a ring around Earth. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Hadean Eon This debris coalesced to form the moon.  When 1st formed, moon was much closer (20,000 km).  Today it is 19x farther away (384,000 km).  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Hadean Eon  Earth was inhospitable; a molten surface.  Evidence of solidified igneous rock dates from 4.4 Ga. This evidence is from zircon grains, not a whole rock. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Hadean Eon  Volcanic outgassing created a deadly atmosphere.    N2, NH3, CH4, H2O, CO, CO2 and SO42- were components. This atmosphere had a greater density that today’s. Early formed crust was bombarded by meteorites.  Meteorite impacts were abundant between 4.0 and 3.9 Ga. This would have destroyed early formed crust. Oldest evidence of crust is 4.03 Ga. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Hadean Eon  The first oceans formed as rain from the skies. Liquid water required cooling of the surface.  First evidence of oceans from marine sediments ~ 3.85 Ga.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon Time of significant change to planet Earth.  ~3.8 Ga, Earth had cooled to form lithosphere.  Intense meteorite bombardment ceased.  Portions of the rock record begin to survive.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  Had plate tectonics started yet? 2 models. Many small microplates, island arcs and hot spot volcanoes rapidly formed and subducted crust.  Archean lithosphere was too hot to subduct; hot spot plume volcanics dominated formation of crust.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  Volume of continental crust increased dramatically. 85% of modern continental area present by end Archean.  Signals full development of plate tectonic processes.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  How did continental crust form?  Low density felsic rocks formed above subduction zones. Felsic crustal blocks grew via continental collision. Felsic sediments accumulated near continental crust.  Mantle hot spots built mafic volcanoes. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  How did continental crust form?  Continental crust is too buoyant to subduct. Jams subduction trenches. Shuts off subduction. Creates thickened, uplifted continental crust.  Frequent collisions sutured volcanic arcs, hot spots and sedimentary debris together as protocontinents. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  The 1st cratons had formed by 2.7 Ga. Cratons are… Long-lived blocks of durable continental crust.  Too buoyant to subduct, these blocks persist over time.  Cratons are the interior core of modern continents.  Continents grow as rocks are added to cratons.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  Archean cratons consist of 5 principle rock types. Gneiss – Hi-grade metamorphics from Archean collisions.  Greenstone – Metamorphosed fragments of mafic rocks.  Granite – Magmas from partial melting of the crust.  Graywacke – Sedimentary debris derived from arcs.  Chert – Silica precipitated in the deep sea.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  Archean shallow sediments are poorly known. There were few shallow depositional settings, or…  Few examples have survived destruction by erosion.   Sedimentary processes were clearly operating.  Transport rounded sediment grains. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  Life first appeared during the Archean. Evidence? Biomarker molecules.  Isotopic signatures.  Preserved fossil cells.   Clear evidence of life in rocks dated to 3.5 Ga.   Life may have started earlier. Oldest undisputed bacteria fossils ~ 3.2 Ga. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Archean Eon  Rocks after 3.2 Ga contain stromatolites. Layered mats of cyanobacteria (blue-green algae).  Sediments stuck to mucous coatings on algal filaments.   Photosynthesis changed Earth’s atmosphere.  Converts CO2 and H2O to organic matter and free oxygen. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Protero = first; zoic = life.  Named before Archean life was discovered. ~ 2 Ga (2.5 to 0.542 Ga); almost ½ of Earth history.  The unfamiliar Archean world changed to…  Fewer, larger lithospheric plates.  Larger continental landmasses.  An oxygenated atmosphere.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  New continental crust formed, but at slower rates. 90% of Earth’s continental crust by the middle Proterozoic.  Continents grew by addition of volcanic arcs.  Continents cooled and strengthened to become cratons.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Case History: The assembly of North America.  A large area of Pre-Cambrian rocks outcrops in Canada. This constitutes a shield – a low-lying area of Pre-C rocks.  The cratonic platform occurs to the S and W of the shield. Phanerozoic strata cover the Pre-C shield. Shield rock underlies much of U.S. Encountered by drilling. Exposed in the Grand Canyon. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Canadian Shield consists of many distinct blocks. Sutured Archean crustal blocks form the shield interior.  Added volcanic arcs and crustal slivers extended  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Continental collision created Pre-C supercontinents. Rodinia – Formed ~ 1 Ga.  The Grenville Orogeny formed an extensive mountain belt.   Pannotia – A short-lived supercontinent ~ 600 Ma. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Atmospheric oxygen (O2) skyrocketed 2.4 to 2.2 Ga.  Currently, O2 is 21% of the atmosphere.  Before 2.2 Ga, detrital pyrite in sediments indicated no O2. Redbeds (red from Fe-oxides) don’t appear before 2.2 Ga.  Banded Iron Formations (BIFs) – Fe dissolved in the ocean reacted with O2, forming world wide iron oxide deposits.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Atmospheric O2 permitted diversification of life.  Aerobic respiration more efficient; allowed multicellular life. Without O2, only single celled organisms possible. Eukaryotic (nucleated) cells evolved by at least 1.0 Ga.  The possibility of a land-dwelling biota. O2 made formation of the ozone layer possible. Ozone absorbs deadly ultraviolet (UV) radiation. Prior to the ozone layer, exposed land was bathed in UV. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Over the last 500 Ma of the Proterozoic…  A gigantic leap in biological complexity. Simple organisms gave way to complex ones.  Ediacaran fauna – Unusual soft-bodied fossils. Preserved in end Proterozoic sediments.  Multicellular invertebrates resembling worms and jellyfish.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Proterozoic Eon  Ediacaran fauna arose in conjunction with 2 events. The assembly and breakup of the Pannotia.  Global cooling possibly resulting in a “Snowball Earth.”  Most of the world bears evidence of being frozen. Life diversified rapidly after snowball conditions waned. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Phanerozoic Eon Phaneros = visible; zoic = life.  The most recent 542 Ma of Earth history.   Began with appearance of diverse hard-shelled organisms. Hard-shells vastly increased fossil preservation. Made possible a more complete archive of life on Earth. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Phanerozoic Eon  The Phanerozoic is divided into 3 Eras. Paleozoic – Ancient life.  Mesozoic – Middle life.  Cenozoic – Recent life.   Eras emphasize changes in Earth’s biota. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Phanerozoic Eon  Tectonic plates and continental blocks rearranged. Ancient changes in paleogeography have been deciphered.  The map of Earth looked different throughout the Eon.  New supercontinents formed and rifted apart.  Numerous orogenic belts were created and eroded.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Phanerozoic Eon Phanerozoic sea-level (SL) has changed often.  SL highstands flooded continental interiors.    Rising SL (transgression) initiated sediment deposition. SL lowstands exposed continental margins.  Falling SL (regression) initiated erosion or non-deposition. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Phanerozoic Eon SL cycles are marked by large-scale unconformities.  Stratigraphic sequences reflect SL highstands.  Rising SL invaded further inland with passing time.  Falling SL moved progressively outward from the interior.  Unconformities…  Become younger toward continental interiors. Bound less time in the interior; more time along the margins. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Early Paleozoic  Cambrian and Ordovician Paleogeography:  Rifting of Pannotia left 4 large continental fragments. Gondwana – (S. America, Africa, Antarctica, India, Australia). Laurentia – (N. America and Greenland). Baltica – (Europe). Siberia.  Part of Gondwana was over the South Pole in the late Ordovician. Marked by glacial deposits. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Early Paleozoic  Cambrian and Ordovician Paleogeography: The rifted continents developed passive margins.  Rising seas flooded expanses of continental crust.  Epicontinental seas were shallow, warm and sunlit. Thriving marine life preserved as fossiliferous sediments. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Early Paleozoic  Cambrian and Ordovician Paleogeography: Subduction carried a volcanic arc toward Laurentia.  Mid-Late Ordovician: continental crust jammed the trench.  Passive margin sediments were deformed by the collision.  A volcanic arc was welded onto the margin.  The “Taconic Orogeny” was the 1st Appalachian event.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Early Paleozoic  Cambrian and Ordovician Life Evolution: Earliest Cambrian – Hard shells appeared for the 1st time.  Massive diversification followed: the “Cambrian explosion.”  Reflects the evolution of a complex ecosystem.  Plankton, deposit feeders, giant predators. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Early Paleozoic  Cambrian and Ordovician Life Evolution:  Life during the Ordovician included several “firsts.” The 1st vertebrates were jawless fish (agnathans). The 1st crinoids (flower-like echinoderms). The 1st green algae and primitive land plants. The end of the Ordovician witnessed a mass extinction.  The seas roiled with life, but there was no life on land yet.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Middle Paleozoic  Silurian and Devonian Paleogeography:  Silurian climate warmed to create greenhouse conditions. Epicontinental seas expanded. Gigantic reef complexes developed in normal salinity water. Thick evaporite deposits accumulated in isolated ocean basins. The Taconic mountains eroded away. Sediment was shed to either side of the eroding source.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Middle Paleozoic  Silurian and Devonian Paleogeography:  A 2nd eastern orogenic phase occurred in the Devonian. The Avalon microcontinent was welded onto North America. Large mountains marked the Acadian-Caledonian Orogeny. Vast sediment aprons spread outward from the uplift. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Middle Paleozoic  Silurian and Devonian Paleogeography:  In the west, thick passive-margin sediments accumulated. An island arc smashed this margin in the Late Devonian. This created the Antler orogenic belt. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Middle Paleozoic  Silurian and Devonian Life Evolution: New species replaced those lost to extinction.  Vascular land plants evolved and spread across Earth.  Internal water transport systems. Woody tissues. Seeds.  Land plants changed Earth. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Middle Paleozoic  Silurian and Devonian Life Evolution:  Fish rapidly evolve and proliferate. Jawed fish. Boney fish.  The 1st land animals followed plants. Scorpions. Spiders. Insects. Crustaceans. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Middle Paleozoic  Silurian and Devonian Life Evolution:  At the end Devonian, the 1st amphibians appeared. Walked on legs. Breathed air with lungs. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Paleozoic  Carboniferous and Permian Paleogeography: Climatic cooling followed the Mid-Paleozoic greenhouse.  Seas regressed from continents.  Clastics choked out carbonates.  Thick coals formed equatorially.  Ice sheets spread across Gondwana.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Paleozoic  Carboniferous and Permian Paleogeography: Continental collisions formed the supercontinent Pangaea.  Gondwana collided with Laurentia (Alleghenian orogeny).  North America collided with Africa. The Gulf Coast collided with South America.  Collisions were oblique. Folding. Thrust faulting. Strike-slip faulting. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Paleozoic  Carboniferous and Permian Paleogeography:  The Appalachians preserve several types of geology. Thin-skinned thrust faulting over basement rock. Produced the Appalachian fold-thrust belt (Valley and Ridge). Deformation above a large horizontal detachment fault. A more intensely deformed and intruded metamorphic core. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Paleozoic  Carboniferous and Permian Paleogeography:  The assembly of Pangaea had other tectonic effects. Deformation was transmitted across Laurentia. Basins and uplifts formed in the mid-continent. Hercynian orogen - Africa collided with S. Europe. Ural Mountains – Europe collided with Siberia. China attached to southern Siberia. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Paleozoic  Carboniferous and Permian Paleogeography:  Pangaea was a massive supercontinent. The interior was a vast desert far from ocean moisture. Large deposits of red (oxidized) dune and fluvial sandstones. Large accumulations of evaporites. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Paleozoic  Carboniferous and Permian Life Evolution:  Life continued to evolve. Dense tropical wetlands hosted vegetation and giant insects. Amphibians diversified. Reptiles appeared for the 1st time. The amniote egg permitted reproduction away from water. Reptiles populated previously inhospitable environments. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Paleozoic  Carboniferous and Permian Life Evolution:  The Paleozoic ended with the Permian extinction. 90% of all marine species disappeared. Some evidence links the extinction to a bolide impact. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Early and Mid-Mesozoic Era  Triassic and Jurassic Paleogeography: The supercontinent Pangaea lasted 100 million years.  Pangaea began to rift late Triassic to early Jurassic.  Rifting started in the North Atlantic. A thin narrow ocean had opened by the end Jurassic. This basin accumulated thick evaporite deposits. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Early and Mid-Mesozoic Era  Triassic and Jurassic Paleogeography: Pangaea's interior was hot and dry.  Greenhouse climates cooled by the mid-Jurassic.  Transgression flooded much of the Rocky Mountain region. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Early and Mid-Mesozoic Era  Triassic and Jurassic Paleogeography:  Western North America was an active margin. Subduction created island arcs. Collision added arcs and microcontinents to N. America. Sonoma orogeny – Perm – Tri. Nevadan orogeny – Late Jur. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Early and Mid-Mesozoic Era  Triassic and Jurassic Life Evolution:  New species filled niches vacated by extinction. Corals became dominant reef builders. Gymnosperms proliferated. Reptiles diversified. Plesiosaurs – Swimming reptiles. Pterosaurs – Flying reptiles. Turtles appear. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Early and Mid-Mesozoic Era  Triassic and Jurassic Life Evolution: By end of the Triassic the first true at dinosaurs appeared.  Dinosaurs differ from other reptiles in significant ways.  Legs are positioned beneath their bodies. They bear evidence of warm bloodedness.  By the end Jurassic giant sauropods were abundant. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • Early and Mid-Mesozoic Era  Triassic and Jurassic Life Evolution: The 1st feathered birds (archaeopteryx).  The 1st ancestors of mammals appeared at Triassic.  They resembled small rat like creatures. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  Cretaceous Paleogeography:  Climate continued to warm; seas flooded the continents. An ocean connected the Gulf of Mexico to the Arctic. Epicontinental seas accumulated limestone and sandstone. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  Cretaceous Paleogeography:  Breakup of Pangaea continued through the Cretaceous. South America separated from Africa. Antarctica separated from Australia. India broke from Gondwana and raced toward Asia. Passive margins developed along the Atlantic. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  Cretaceous Paleogeography:  In western North America the Sierran continental arc grew. Arc volcanoes have long eroded away. Roots of the arc are exposed as the Sierra Nevada batholith. An accretionary prism grew on the overriding plate. These sediments form the present day Coast Range. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  Cretaceous Paleogeography:  Sierran Arc compression initiated the Sevier orogeny. Large thrust faults moved to the east of the arc. The Sevier fold and thrust belt elevated the Canadian Rockies. A large foreland basin formed east of the thrusting. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  Cretaceous Paleogeography:  Laramide Orogeny – Late Cretaceous basement uplifts. Reverse faulting due to continued compression to the west. Uplifts appear in Wyoming, Colorado, Utah and Arizona.  Basement faulting folded overlying Paleozoic strata.  Results: Large monoclines and uplift of Rocky Mountain Front. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic Orogenic events suggest complicated feedbacks.  Rifting of Pangaea led to mid-ocean ridges (MORs).  Seafloor spreading operated 3x faster.  Huge submarine plateaus formed from flood basalt.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic The Late K was a time of unusual volcanic activity.  Attributed to unusually large hot spots.  Late K volcanism influenced the climate.   Volcanic CO2 (8x modern values) warmed the atmosphere.  Melting ice caps contributing to sea level rise. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  Cretaceous Life Evolution:  Teleost fish appeared and became dominant. Symmetrical tails, specialized fins, short jaws, rounded scales. Swimming reptiles and gigantic turtles swam the seas.  Angiosperms (flowering plants) appeared and spread.  Produce seeds rapidly. Insects facilitate pollination. Hardwood trees proliferated. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  Cretaceous Life Evolution:  Dinosaurs reached their evolutionary peak. Inhabited almost all environments on earth. Social herds of grazing dinosaurs roamed the plains. Large carnivores fed upon the herbivores. Pterosaurs soared overhead, birds began to diversify.  Mammals developed larger brains and specialized teeth. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  The K-T (Cretaceous–Tertiary) boundary event.  There is abundant evidence of catastrophic change. Instantaneous global change in fossil assemblages. Sudden mass extinction of most species on earth. The dinosaurs which had ruled the planet for 150 Ma vanished. 90 percent of plankton disappeared. 75% of plant species vanished. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  The K-T (Cretaceous–Tertiary) boundary event. Catastrophic impact by a 10 km comet or meteorite.  The Chicxulub crater lies beneath the northern Yucatan.  Radiometric dating indicates the crater formed at ~ 65 Ma. 100 km wide; 16 km deep.  Periodic impacts are likely contributors to other extinctions. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  The K-T (Cretaceous–Tertiary) boundary event.  Evidence for an impact end to the Mesozoic? Thin clay interrupts deep-sea chalk at the K-T boundary. This suggests that, for a short time, all plankton died. Iridium in the clay is rare on Earth; common in meteorites. Iridium enriched clay found at the K-T boundary worldwide. The clay contains shocked quartz and tiny glass spheres. An immense impact best explains these features. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  The K-T (Cretaceous–Tertiary) boundary event.  What did the impact do to Earth? The impact blasted debris into the sky from a huge crater. It created a gigantic tsunami (2 km high). The blast of hot air set forests on fire. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Late Mesozoic  The K-T (Cretaceous–Tertiary) boundary event.  What did the impact do to Earth? Dust in the atmosphere would have blotted out the sun. Sulfate from vaporized gypsum created sulfuric acid rain. Lack of sunlight shut down photosynthesis. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era Cenozoic (65 Ma-present) – The most recent history.  Cenozoic Paleogeography:  During the last 65 Ma, Earth has continued to change.  The final stages of the breakup of Pangaea.  Australia detached from Antarctica. Greenland separated from North America The North Sea formed between Britain and Europe. Sea-floor spreading continued to open the Atlantic Ocean. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Paleogeography:  Fragments of Gondwana collided with Europe and Asia. Closed the Tethys Ocean. Deformed and uplifted the Alpine-Himalayan chain. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Paleogeography:  Pacific margins of the Americas continued convergence. Andes grew as a continental volcanic arc. Rocky Mountains grew by thrusting and basement uplift. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Paleogeography:  The large Farallon plate was almost completely consumed. A transform fault replaced part of the Farallon trench 40 Ma. The San Andreas / Queen Charlotte fault system formed. The Juan de Fuca plate remains as a Farallon remnant. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Paleogeography:  East-west extension started to stretch southwestern N. Am. A broad continental rift stretched and thinned the crust. This region is called the Basin and Range Province. Elongate N-S linear mountain ridges (ranges). Ranges are separated by N-S linear valleys (basins). This geometry reflects normal fault block rotation. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Paleogeography: Global climate has gradually cooled since the Cretaceous.  The Antarctic ice cap reappeared in the early Oligocene.  Continued cooling led to the formation of grasslands.  The Isthmus of Panama emerged 2.5 Ma.  Isolated circulation between the Atlantic and the Pacific. Permitted the Arctic Ocean to freeze. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Paleogeography:  The Quaternary Period (2 Ma – present): Cool climate. Pleistocene ice ages – Continental scale glaciation. Glaciers have advanced and retreated at least 20 times. Modern landscapes sculpted by glacial erosion /deposition. Climate warmed 11 Ka; Earth is currently in an interglacial. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Paleogeography:  The Quaternary Period (2 Ma – present): Cool climate. Pleistocene ice ages – Continental scale glaciation. During ice ages, SL fell exposing continental shelves. Shelves acted as land bridges for human and animal migration. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Life Evolution: After the K-T boundary, plant life recovered.  Forests of angiosperms and gymnosperms reappeared.  The 1st grasses appeared in the middle Cenozoic.  Dinosaur descendants (birds) diversified and spread.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Life Evolution: The Cenozoic is known as the age of mammals.  Mammals rapidly diversified to fill vacated niches.  By mid-Cenozoic huge mammals appeared.  Woolly mammoths. Giant beavers. Ground sloths.  Late Cenozoic, human ancestors 1st appeared. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Life Evolution: Ape-like primates diversified in the Miocene (~ 20 Ma).  The 1st human-like primate appeared about 4 Ma.  The first members of the genus Homo appeared to 2.4 Ma.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Cenozoic Era  Cenozoic Life Evolution:  What sparked the evolution of the genus Homo? Climate changes that led to the spread of grasslands? Permitted departure from the trees. Life on the ground allowed more time for infant development. This permitted growth of larger brains.  Homo erectus appeared ~ 1.6 Ma. Made stone axes. Homo sapiens appeared ~ 500 Ka.  Modern humans appeared ~150 Ka.  Many giant mammals died off 10 Ka.  Climatic change? Hunting pressure by humans? Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • The Geologic Time Scale Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 13: A Biography of Earth
  • W. W. Norton & Company Independent and Employee-Owned This concludes the Norton Media Library PowerPoint Slide Set for Chapter 13 Earth: Portrait of a Planet 3rd Edition (2008) by Stephen Marshak