biography of the earth 2 Flashcards
know dates of periods or eras
eras
early and middle mesozoic
Jurassic
Triassic
Pangea
Begins rifting in the Triassic
Narrow North Atlantic
During Jurassic period
Western North America
Convergence with subduction
“Gluing” accreted terranes
Sevier Orogeny and the Sierran arc
Inland
-Mountain building
Coastline
-Volcanics and intrusions
Early (Triassic) Mesozoic Life
Ecological niches left empty by Permian extinction
New species fill in
Corals proliferate
Gymnosperms dominate
- Seed-producing trees (conifers, cycads, ginkgo, etc)
Marine reptiles
Flying reptiles
Late Triassic
True dinosaurs have evolved
middle mesozoic life
Dinosaurs!
Differ from other reptiles by having their legs beneath their bodies
Some may have been warm-blooded
Avian
-Birds (not extinct)
Non-avian
-Extinct
late mesozoic
Cretaceous
Western North America
Compression continues
ex:
Sierran arc
Today exposed as the Sierra Nevada Batholith
Mountain building events
Sevier Orogeny
Wasatch Mountain folds and thrusts
Laramide Orogeny (late Cretaceous)
Rocky Mountains
late mesozoic: india
India has broken from Gondwana
Headed north at an “anomalously fast speed”
180mm/y
(more than twice the speed of present-day plates) woah
late cretacious climate
The global climate warmed dramatically during the Cretaceous period. What types of impacts would this warming have on:
Glacier formation: There were NO glaciers or sea ice on the earth—not even at the poles
Sea level; Because large volumes of water were not locked up on the continents, sea level was up to 170 m higher than present day
Types of rocks deposited: Large swaths of the continents were covered with warm, shallow seas—LIMESTONE!
Ocean temperatures: Tropical waters
82-111° F (28-44° C)
Polar waters
40° F (4.5° C)
Insect size: Oxygen levels were 50% higher than present Insects “breathe” through tiny openings in their bodies—higher oxygen partial pressure allows larger organisms
why did it get so warm in the late mesozoic era
Atmosphere contained 3-6 times more carbon dioxide than today
- Decay of large amounts of dead plants
- Extreme volcanism
- High mountains weathering carbon-rich rocks (mostly limestones)
- we’re not 100%sure
end mesozoic: mass extinction
Mass extinction occurred 65 million years ago
Could it have been caused by the impact of a large meteorite?
Boundary clay worldwide (K-Pg boundary)
-Boundary between Cretaceous (K) and Tertiary (now Paleogene, Pg)
- KPg at the end of the Mesozoic Era
- Exact age of the major extinction in which dinosaurs disappeared from Earth
~66 Ma
- Abundant tropical plant fossils below, clay marks global fires, no plants above
- Concentrations of iridium and shocked quartz
impact at the end of mesozoic era discovery of why
Developed by father and son team—Walter (geologist) and Luis Alvarez (physicist, Nobel laurate)
With chemists Frank Asaro and Helen Michel
found:
Ejecta found worldwide
Thickest in Caribbean
Led the search to the Yucatan peninsula of Mexico
Impactor was an asteroid 10 to 15 km across.
Chicxulub Crater
see screen shot
Chicxulub Impact
Ejecta
42 seconds after impact, column of debris is 100 km high
Perspective:
Space begins at 100 km high
Mount Everest
8.8 km above sea level
Tallest building in the world (Burj Khalifa, Dubai)
0.8 km tall
Part of God’s Plan?
Opening habitats for the proliferation of mammals was an essential step in the sequence that led to the eventual emergence of Homo sapiens. Without this ancient catastrophic event, neither you nor I would now be here… If we accept that this is God’s world and that our conscious, self-reflective existence is part of God’s intention, then Chicxulub was part of God’s action in the universe. Owen Gingrich God’s Universe, Cambridge, 2006
cenezoic paleography
Convergence
Subduction
East Pacific
Andean
Cordilleran
Collision
Africa/Arabia /India hits Eurasia
Alpine-Himalayan
