Lecture 10 March 20, 2008. Stump-the-Prof Qs from March 12 Chapter 27: Ice Time Chapter 28: The Mysterious Biped Chapter 29: The Restless Ape Chapter 30: Good Bye Guest lecturer: Ginny Michaux on her polar expeditions and climate change. Stump-the-Prof Q’s from Wednesday, March 12.
KNOWN ERUPTIONS (Estimates of the volume of erupted material are given in parentheses. Mt.St Helens ~ 1 km³; Tambora (1815) ~ 100 km³). “VEI”=Volcanic Explosivity Index (log scale for VEI 7 or higher, the volume ejected must be 1000 km³ or more)
VEI 8 Category:
* Lake Taupo, North Island, New Zealand - Oruanui eruption
26,500 years ago (1,170 km³)
* Lake Toba, Sumatra, Indonesia - 75,000 years ago (2,800 km³)-->Volcanic
winter or ‘Millennial Ice Age’, ~60% human population eradicted
* Yellowstone Caldera, Wyoming, United States - 2.2 million
years ago (2,500 km³) and 640,000 years ago (1,000 km³)
* La Garita Caldera, Colorado, United States - Source of
the truly enormous eruption of the Fish Canyon Tuff 27.8
million years ago (~5,000 km³)
VEI-7 Category: see http://en.wikipedia.org/wiki/Supervolcano
Note: For large flood basalt eruptions, see “large igneous province”, also categorized as ‘super volcanoes’, though not explosive.
How bacteria acquire immunity to antibiotics are given in parentheses. Mt.St Helens ~ 1
Spontaneous DNA mutation: e.g.
Microbial sex (called transformation):
e.g. Penicillin-resistant gonorrhea
Scariest: plasmid, that can flit from
one type of bacterium to another and
provide resistant to multiple antibiotics
Following mutation in bacterial DNA, natural selection takes over.
Migration paths and the spread of Homo-XX are given in parentheses. Mt.St Helens ~ 1
“Out of Africa Again and Again”: research by Alan Templeton. Based on use of 13 haplotypes = long-lived chunks of genome, together with a fossil-calibrated molecular clock.
[Taken from: “The Ancestor’s Tale”
By Richard Dawkins]
Warmer are given in parentheses. Mt.St Helens ~ 1
Departure of 18O
from normal, as
measured in cores
from ocean bottom
Thousands of years before present (BP) are given in parentheses. Mt.St Helens ~ 1
Thousands of years before present (BP)
Milankovitch cycles: change in eccentricity of Earth’s orbit around the Sun. Period about 96,000 years.
Milankovitch cycles: Obliquity of Earth’s rotation. orbit around the Sun. Period about 96,000 years.
Period about 41,000 years.
Milankovitch cycles: precession of Earth’s orbital axis. orbit around the Sun. Period about 96,000 years.
Period about 19-21,000 years.
Changes in Solar Insolation (amount of energy from Sun) over past 1 Million years due to Milankovitch cycles.
Note: This is for a specific
Milankovitch got it right! past 1 Million years due to Milankovitch cycles.
CO past 1 Million years due to Milankovitch cycles.2 from gas trapped in
T from 18O/16O ratio in
Time history of atmospheric CO2 concentration (on the left)
and mean temperature (on the right). Note that T tracks
CO2 concentration very closely. (Actually, CO2 lags T changes)
Snowball Earth? ice ages
Possible snowball Earth periods in the Proterozoic
Example of computer simulation
In previous warm ups, rise in T PRECEDED rise in CO ice ages 2 by several
100 years. Now T and CO2 are tracking each