earth history geol 2110
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Earth History GEOL 2110. Lecture 2 Scales of Time and Change. Major Concepts. Geological events cover huge amounts of time that are hard to grasp in the span of human life - PowerPoint PPT PresentationTRANSCRIPT
Earth History GEOL 2110
Lecture 2Scales of Time and Change
Major Concepts
• Geological events cover huge amounts of time that are hard to grasp in the span of human life
• We tend to focus on dramatic, short-lived geologic events that we witness and are unaware of subtle, but geologically important events
• Very often, short dramatic events are just parts of long-lived processes (e.g. mountain building, sea-level change)
• Rates of geologic change can be linear, non-linear, periodic or episodic
Dramatic, Short-lived EventsVolcanic Eruptions
Krakatoa , 1883• left a 3000m deep crater• ash dispersed 2000km away• heard 5000km away• 40m high tsunamis• lowered global T for 2yrs
Dramatic, Short-lived EventsVolcanic Eruptions
Santorini/Thera – 3,600ybp• 3-4x bigger than Krakatoa• Minoan civilization on Crete to devastated by
earthquakes and tsumamis• Inspired the myth of the lost city of Atlantis
Dramatic, Short-lived EventsVolcanic Eruptions
Mt. St. HelensMay 18, 1980
Summit -9,677’
Crater Base -4,700’
Dramatic, Short-lived EventsVolcanic Eruptions
Mt. Mazama Eruption6,500 ybp
Great Time Markers!
Dramatic, Short-lived EventsVolcanic Eruptions
Heimaey, Iceland1983
1326 Aftershocks
Dramatic, Short-lived EventsEarthquakes
1326 Aftershocks
Dramatic, Short-lived EventsEarthquakes
Anchorage, Alaska1964
9.3, 131 Dead
Dramatic, Short-lived EventsEarthquakes
San Francisco, California - 19067.8
200,000 homeless and >3,000 dead3 days of fires destroys 70% of city
Dramatic, Short-lived EventsTsunamis
Banda Aceh, Sumatra
9.15
>200,000 killed
Dramatic, Short-lived EventsIn Real Time
Earthquakeshttp://earthquake.usgs.gov/earthquakes/map/
Volcanoeshttp://www.volcano.si.edu/reports/usgs/
Subtle Geologic EventsClimate Change
The Sahara10,000 Years ago – Temperate, Humid, Verdant
Subtle Geologic EventsClimate Change
Subtle Geologic EventsGlaciers and Sea Level
Subtle Geologic EventsGlaciers and Sea Level
Cosquer Cave, France37 m deep entrance
Horse - 18,500 years old
Ibex
Subtle Geologic EventsGlaciers and Sea Level
Greenland's Jakobshavn Glacier
Subtle Geologic EventsGlaciers and Sea Level
Projected sea level rise (5 m) for NorthwesternEurope. Population at risk in the inundation area is calculated at over 21.7 million people(Rowley et al. 2007)
Current climate models predict that sea levels will rise 25-60 cm over the next century
Melting 10% of Greenland and Antarctic Ice Sheets would produce ~5 m rise in sea level
Subtle Geologic EventsGlacial Retreat & Crustal Rebound
Subtle Geologic EventsGlacial Retreat and Crustal Rebound
Subtle Geologic EventsGlacial Retreat and Crustal Rebound
Rates of Geological Processes
Linear Change(rare in nature) Non-Linear Change
(more common)
Rates of Geological ProcessesPeriodic to Episodic Change
Most Common toGeological Processes
Evolution of Ideas about Rates of Geological Processes
Pre-1700
Late 1700’s- Mid-1800’s
Mid-1800’s –Late 1900’s
Present-day
Biblical Creation <6000yDeluge central to geological interpretation
Catastrophism
UniformitarianismPuNctuAteD eQuiLibRiuM
Next Lecture
Development of Geological Concepts
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