Wednesday, January 25, 2012

Lecture 5

Lecture 5: Wednesday, January 25, 2012

• By now you should have completed through chapter 10 of the book
• February 10: Film Little Ice Age, Big Chill
• Film will set the tone for the following two lectures; major component of exam
• Assignment 1 Handed out next class – Print out
• Burnside Hall 512 Feb 10 11-1, Feb 15 1-3

• Book: Ice Ages, Solving the Mystery, John Imbrie and Katherine Palmer Imbrie

Louis Agassiz
• The first to theorize Ice Age theory?
• Other people had presented papers but no one else had te personality that he did to become a dynamic speaker
• Ignace Vinetz: systemized the whole thing and figured out they were glaciated
• Categorized evidence for glaciation
• Gave this information to Louis Aggassiz, he did not believe them until they went to above’s house and showed him the evidence

• SLIDE: Who else played a role in theorizing Ice Age theory?
• Swiss who lived and worked in the __
• John-Pierre Parraudin: striations on rocks caused by pressure of glaciers
• Ignace Vinetz: Swiss Engineer characterized glacier movements, deduced glaciers were once far more extensive, covering all the valleys in the Alps nearby
• Jens Esmark: Norwegian mineralogy professor found smilar evidence for former greater glacier extent in Norway

Reverend Professor William Buckland
• Why did Agassiz target him
• To confirm the evidence of natural religion and to show that the facts developed by it are consistant with the accounts of the creation and accounts of day luge in the bible
• To show that Noah’s flood was the cause for the current physical landscape
• Was a good lecturer
• The fact that the evidence was the same in so many places convinced him

• Erratic boulders: carried in the ice from their bedrock origin, brought down and dropped somewhere
• Glaciers are like rivers of ice – they move the rocks around and mix them up
• Not as much as a river because it is not as fluid, but you get the idea
• The boulders are a little less angular because the glacier erodes them
• Ice-rafted boulders more angular
• River rocks are very smooth because the water keeps going over them
• Striated rocks: rocks with starches caused by the weight of ice/glacier that is laden with rock and other debris, moving over them
• Polished rocks: rock surfaces that have been fround smooth or grooved by pebbles and sand grains carried in ice, where larger rocks would cause striations; very smooth and shiny; rain washes this finish away; evidence of an area where glaciers have recently receded or has been covered with soil
• Moraine: unsorted debris that accumulates at the terminus and sides of glaciers and in the middle where two glaciers meet
• Debris piles along edges
• Terminal moraine is the furthest extent of the glacier
• The glacier recedes and can stay there for several years creating more moraines

What is Ice Age Theory?
• States that in the past, glaciers and ice sheets occupied a much larger area than they do today

The Initial Evidence

Charles Lyell
• Most renound geologist at the time; not really respected
• Developed ice raft theory
• There is not enough water; in order for the day luge to have happened in the alps, it would have had to come from somewhere; there is no evidence for this at all
• This theory of a “flood” comes from many different cultures
• Timing coincides with the melting of the ice sheets at the end of the last glacial maxiumum
• Noah’s flood/ Day luge are in so many different cultures; experienced rising sea level
• Sea level dropped 350 feet from where it is today when the ice age started
• How did Buckland convince Lyell? - took him to the moraine and admitted that the ice age theory explains things that he couldn’t explain before

Hypotheses Suggested to explain what caused the ice ages
• Sun spots, solar activity: their impact is so minimal that it is not even worth mentioning
• Dust partices: more dust particles create cooling because they reflect sunlight back into the atmosphere; could also make the sun shine brighter
• Carbon dioxide levels: low levels could cause an ice age, but no one can figure out what would have caused the low levels
• Volcanic Eruptions: the effect of a volcanic eruption is short term
• Lyll: tectonic activity; the higher up the mountain you go, the colder it gets: this would take millons of years
• James Geikie
• Iceland grows an inch every 100 years (on a plate boundary); for an uplift to occur, it just does not add up

The energy Source that drives the ice age
• The energy that keeps the climate machine running, that causes the winds to blow and the currents to flow comes from the sun

Astronomical Theory
• The 3 components of astronomical theory
• Precession, eccentricity, obliquity
• Equinox: 12 hours of daylight, 12 hours of darkness (Spring and Fall); Earth is at a neutral angle to the sun; not towards it and not away from it
• Will talk about in more detail next week
• Obliquity: has to do with the tilt/angle
• Tropic of Cancer and Tropic of Capricorn; 23.5 degrees because that is the angle that the Earth’s axis tilts (they are the same)