UNIT-2-2014-DAY-1-PM-Instruction-Major Events in Earth History

Open Earth Systems: An
Earth Science Course
For Maryland Teacher
Professional Development
DAY 1 - Weds. July 9
AM Instruction: Solar System Origin, Early Earth & Habitability
AM Activity: Dating the Earth – Simulating Radioactive Decay
PM Instruction: Major Events in Earth History
PM Activity: Exploring Geologic Time with TS-Creator
DAY 2 - Thurs. July 10
AM Instruction: Climates of the Past
AM Activity: Weathering, Erosion and Soils
PM Instruction: The Fossil Record of Life
PM Activity: Fossil Identification
LINDA HINNOV, Instructor
Origin of Moon
Late Heavy Bombardment
Plate Tectonics
Great Oxidation Event
Snowball Earths
Cambrian Explosion
Life invades Land
Mass Extinctions
Earth history highlights
J. Valley, Wisconsin
Origin of Moon
Canup, 2013
Late Heavy Bombardment
Earth’s Impact History
Late heavy bombardment
Ocean vaporizing event
Earth craters (filled boxes)
Chiron (future)
Moon craters (open boxes)
From 4.0 to 3.8 Ga,
the Late Heavy
occurred, which
would have vaporized
the ocean and
exterminated any
pre-existing life;
accordingly, we
name the upper
Neohadean period
Kasting and Catling, 2003
Plate Tectonics
“Faint young sun paradox”
“Faint young sun paradox”
One solution:
Kasting, 1987
Another solution: Earth was closer to Sun
Great Oxidation Event
– 3.5 Ga
– Suggest photosynthesis
Biomarkers for cyanobacteria
– 2.7 Ga
Release of free oxygen into the atmosphere
The boring billion
Secular variation in d¹³C values of marine carbonates from 2.5 Ga to
present. Triangles indicate times of extensive glaciation. Note
extreme late Neoproterozoic isotopic variability and correlation at
that time of negative excusions with glaciations.
boring billion
First eukaryotes
Some of the earliest known single-celled
eukaryote fossils are acritarchs, which
become conspicuous at about 2.1 billion
years ago. Acritarchs are the most common
fossils of the late Proterozoic. Some are
thought to have been the resting stages, or
cysts, of dinoflagellates, which are one of
the most prominent groups of planktonic
algae today. Whatever their origin, the
large size of many acritarchs (typically 60 to
200 microns or larger) indicates they were
Vendotaenid algae from Namibia. Image from
D. Erwin, NMNH.
Snowball Earths
boring billion
Hoffman and Schrag, 2000
Ediacaran biota
The Ediacaran Fauna from 600-545 million years ago - includes the earliest-known
multicellular animals:. NMNH Diorama.
Charnodiscus (large, orange sea pen); Ediacara (three large
jellyfish); Dickinsonia (large segmented worm); and Spriggia
(slender, green segmented worm)
Plants invade Land
A progressive increase in soil depth and geographic extent
during the Devonian and Early Carboniferous is strongly
associated with the development of plant rooting systems. Root
traces become more frequent and extensive during the Middle
Devonian, but most are still relatively shallow (<20 cm).
Mass Extinctions
1. Short event (~1 Myrs)
80-96% marine loss
60-75% marine loss
2. Disappearance of > 60%
of species (> 10% families)
3. Global in scale
Shaded band indicates the normal range of
extinction rates, known as "background
extinction." The peaks show the "Big Five"
mass extinction events at the end Ordovician,
Late Devonian, Permian/Triassic (P/Tr)
boundary, the end Triassic, and
Cretaceous/Tertiary (K/T) boundary.
Mass Extinctions
Percent extinction
Proposed Causes
435 Ma
22% families
Global cooling
Glacial deposits in Gondwana
100 m regression
Anoxia during deglaciation!
355 Ma
70-80% species
Global cooling associated with
regression, + stratified ocean and
widespread anoxia
250 Ma
95% species
Cold climates
Formation of Pangea
Siberian volcanism
Methane hydrates
200 Ma
75% species
Manicouagan (Québec) Impact and
CAMP volcanism
65 Ma
30% families
75% species
Chixculub (Mexico) Impact and
Deccan volcanism
Mass Extinctions
Solar activity
Catastrophes of external origin such as solar
activity (e.g., CME’s), bolide impacts, etc.
Catastrophes of internal origin such as
widespread volcanism ("traps"), sudden
methane discharge from ocean-bound gas
hydrates, anoxia, sea level change
Bolide impact
Sea level change
e http://www.flickr.com/photos/
Ordovician-Silurian Mass Extinction
The Ordovician period saw extensive diversification and expansion of numerous marine clades.
Organisms present in the Cambrian were numerous also in the Ordovician; variety of new types
including cephalopods, corals (rugose and tabulate), bryozoans, crinoids, graptolites, gastropods,
and bivalves flourished. Ordovican communities typically displayed a higher ecological complexity
than Cambrian communities due to the greater diversity of organisms. As in the Cambrian,
Ordovician life continued to be restricted to the seas.
The Ordovician extinction occurred at the end of the Ordovician period, the second most
devastating extinction to marine communities in earth history. It caused the disappearance of one
third of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites,
and graptolites. Much of the reef-building fauna was also decimated. In total, more than one
hundred families of marine invertebrates perished in this extinction.
CAUSE: The Ordovician mass extinction has been theorized to be the result of the glaciation of the
continent Gondwana at the end of the period. Evidence for this glaciation event is provided by
glacial deposits discovered by geologists in the Saharan Desert. This caused a lowering of sea level
worldwide as large amounts of water became tied up in ice sheets. A combination of this lowering
of sea-level, reducing ecospace on continental shelves, in conjunction with the cooling caused by
the glaciation itself are likely driving agents for the Ordovician mass extinction.
Devonian Mass Extinction
Following the Ordovician mass extinction rediversification of surviving groups occurred throughout the Silurian
and Devonian. The Devonian saw the first appearance of sharks, bony fish, and ammonoids. During the
Devonian the world's oceans were dominated by reef-builders such as the stromatoporoids, and corals, and
some of the world's largest reef complexes were built. Terrestrial newcomers in the Devonian included
amphibians, insects, and the first true land plants, giving rise to the first forests.
The Devonian mass extinction occurred at the Frasnian-Famennian boundary. The crisis primarily affected
the marine community, having little impact on the terrestrial flora. This same extinction pattern is
recognized in most mass extinctions throughout earth history. The most important group to be affected
were the major reef-builders including the stromatoporoids, and rugose, and tabulate corals. This late
Devonian crisis affected these organisms so severely that reef-building was relatively uncommon until the
evolution of the scleractinian (modern) corals in the Mesozoic era. Among other marine
invertebrates,70% of the taxa did not survive into the Carboniferous. Amongst the severely affected
groups were the brachiopods, trilobites, conodonts, and acritarchs, all jawless fish, and placoderms.
CAUSE: Warm water marine species were the most severely affected, suggesting an episode of global
cooling triggered by a glaciation event on Gondwana, evidenced by glacial deposits in N. Brazil.
Meteorite impacts at the Frasnian-Famennian boundary have also been suggested as possible causes.
Currently, the data surrounding a possible extra-terrestrial impact remains inconclusive, and the
mechanisms which produced the Devonian mass extinction are still under debate.
Permian Mass Extinction
Supercontinent Pangea resulted in the extensive evolution and diversification of Permian terrestrial
vertebrae fauna and a reduction of Permian marine communities. Among terrestrial fauna affected
included insects, amphibians, reptiles (which evolved during the Carboniferous), as well as the dominant
therapsids. Terrestrial flora was predominantly gymnosperms, including the conifers.Marine life included
brachiopods, ammonoids, gastropods, crinoids, bony fish, sharks, and fusulinid foraminifera. Corals and
trilobites were present but rare.
The Permian mass extinction was the greatest ever recorded in earth history. 90-95% percent of marine
species were eliminated as a result of this Permian event. The primary marine and terrestrial victims
included the fusulinid foraminifera, trilobites,rugose and tabulate corals, blastoids, acanthodians,
placoderms, and pelycosaurs, which did not survive beyond the Permian boundary. Other groups that
were substantially reduced included the bryozoans, brachiopods, ammonoids, sharks, bony fish,
crinoids, eurypterids, ostracodes, and echinoderms.
Proposed CAUSES:
Formation of Pangea--reduction of shallow continental shelves due to the formation of the super-continent Pangea. Such a
reduction in oceanic continental shelves would result in ecological competition for space, perhaps acting as an agent for
extinction. However, although this is a viable theory, the formation of Pangea and the ensuing destruction of the continental
shelves occurred in the early and middle Permian, and mass extinction did not occur until the late Permian.
Volcanic Eruptions--result of basaltic lava eruptions in Siberia, which sent sulfates into the atmosphere. Evidence in China supports
that these volcanic eruptions may have been silica-rich, and thus explosive, a factor that would have produced large ash clouds
around the world. The combination of sulphates in the atmosphere and the ejection of ash clouds may have affected global
climatic conditions. The age of the lava flows has also been dated to the interval of the Permian mass extinction.
End-Cretaceous Mass Extinction
Through the Triassic, Jurassic, and Cretaceous, major faunal radiations resulted in a large number of new species
and forms. New terrestrial fauna that made their first appearance in the Triassic included the dinosaurs,
mammals, pterosaurs (flying reptiles), amphibians. The first birds appeared in the Jurassic. Among the terrestrial
flora, the gymnosperms of the Permian remained dominant until the evolution of the angiosperms (flowering
plants) in the Cretaceous. In the Cretaceous major radiations occurred the marine reptiles, rudist bivalves,
ammonoids, belemnoids, scleractinian corals, bivalves, and brachiopods. Marine groups that were present but
did not undergo major evolutionary expansion in the period included the gastropods,bryozoans, crinoids, sea
urchins, and sponges.
During the End-Cretaceous (K-T) extinction (65 million years ago) 85% of all species disappeared, making it the
second largest mass extinction event in geological history. Although dinosaurs were among the unfortunate
victims to perish in the K-T crisis, other terrestrial and marine biotic groups were also severely affected or
eliminated, inclding pterosaurs, belemnoids, ammonoids, marine reptiles, and rudist bivalves. Organisms which
were severly affected included planktic foraminifera, calcareous nannoplankton, diatoms, dinoflagellates,
brachiopods, molluscs, echinoids, and fish. Remarkably, most mammals, birds, turtles, crocodiles, lizards, snakes,
and amphibians were primarily unaffected by the End-Cretaceous mass extinction.
CAUSE: Geologists believe that the widespread distribution of an iridium-rich layer was caused by
meteorite impact, also an abundance of small droplets of basalt, called spherules, in the boundary
layer as evidence that rock was melted and flung into the air upon impact, and shocked quartz.
Recent research suggests that the impact site was in the Yucatan Peninsula of Mexico (Chixlubub
Crater). However, high concentrations of Iridium have also been attributed to the mantle of the
earth, and may be the result of a massive volcanic eruption, e.g., the Deccan Traps - extensive
volcanic deposits laid down at the Cretaceous-Tertiary boundary - of India and Pakistan.

similar documents