Lecture 8

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24 Mar 2011
EESA06 Lecture 8 Page 1
EESA06 Lecture 8
Japan Earthquake:
- Pacific plate going beneath the Philippine plate both going underneath
Japanese mainland (Tokyo is dangerous)
- dµvu]ÁÀZ]PZÁo}ÁµY
- Japan as a whole moved east 25metres t normal is 2.5-3cm/year
o plates were locked build up of stress and energy
o recurrence interval t plates locked for 1000years (superquakes)
- vertical uplift t is what killed people t tsunami and lowered shoreline
Geologic Time and Stratigraphy
- The Earth is 4.56 Billion Years Old
How did we find this out?
1) Early idea on stratigraphy (the study of rock layers as in a book)
2) How layers get bent & broken (lost chapters)
3) Zo]ÀP}(}l~Z]}v]}oZvY
4) Absolute age (isotopic age dating ex: 50 million years)
5) The Geological Timescale: 4.56 to today (similar to a book)
Ancient Greeks recognized fossils embedded in rocks now on top of mountains
- How did they get there? t uplifted
- Strata t beds, older at bottom, deposition and accumulation of older layers
o Can use these to correlate rocks from one location to another
o Aliogeography t trying to find out what it was like in ancient times
^]oµÀu_~Dv]vPZ}((o}}[ t Africa was moving towards North America, collided with east coast
- ^]]o]o]v]}v}(Z[Z]}Çt }lvovµo(}uE}Z[&o}}
- More than one flood recognized t new life created each time so each layer contains different
life forms
Archbishop Ussher (1581-1625)
- Declared in 1625 that ^Z(}uõu}vK}îòthUðììð_ t only 6,000 years old
- Based on counting generation in the Bible
- µY
Georgius Agricola (1494-1555)
- ^(Z}(u]v]vPP}o}PÇ_
- Recognizes that fossil remains are of marine organisms in 1531
Nicolas Steno (1631-86)
- ^u}µv]vv]vo}ÁUovv }vÀÇ(}u}vo}v}Z_
dZ^^}]Zvo]PZuv_~íóïì-1830) t Industrial Revolution, more rational beliefs
- Joseph Black (Pioneer Chemist), James Hutton (Farmer, interest in soil formation), Adam Smith
(Economist, Free Trade), James Watt (Steam Engine, Energy), Walter Scott (Writer)
- An vPo]ZÀ]]}}]vµPZulW^Z/vÁZ]ooZ}}(]vµPZU
- Rational outlook t science based
- Industrialization - Mapping of Oil shale rocks, building of canals
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EESA06 Lecture 8 Page 2
James Hutton (1726-97) t ^&Z}(u}vÇP}o}PÇ_
- Z}Pv^unconformities_Á]Z]voÇ}(}lvZ
igneous origin of granite t gaps in geological record
- W}}}v}(^uniformitarianism_~Zv]
the key to the past) t actualism, same processes observed today
- u]v}}v(o]Á]Zutvv^]oµÀ]o]u_ and
^catastrophism_t catastrophic floods, 6k years old earth
- Facies t uv^v}(_
o Geologists speak of rock facies
- Zµ[^t distinctive shape, igneous intrusion, sill
o First identification of igneous rocks t forms in molten state
- ,µ}v[hv}v(}u]Ç^]W}]v]v^}ov->
John Playfair, geologist (1747-1819)
- The concept of ^d]u_
- ^Zu]vP}ÁP]ÇPÌ]vP}(l]v}ZÇ}(]u_
- Layers in earth
o Secondary Strata t second layer, contained fossils
o Unconformity t gap, earth experienced multiple events
o Primary Strata t first layer
The Great Unconformity at Marmora, Ontario
- Peterborough, hwy7
- Old Iron at bottom, limestone on top with fossils
An Angular Unconformity: 500 million missing years
- Kingston
- Flat lying rocks on top of steeply dipping rocks
The Taconic Unconformity in New York State about 440Ma
- Africa collide with North America
The Igneous Original of Granite
- &}uZo>Çoo[P}o}PÇÆ}}lZW]v]o}('}o}PÇ[1830
The Big Debate of the 19th Century
- Catastropism and Creationism vs. Uniformitarianism and Evolution
- Louis Agassiz (1807-73) vs. Charles Darwin (1809-82)
- Ice Ages t suggested by Agassiz
The Industrial Revolution (1790-1820)
- t[^uvP]v t need for coal
- Scientific Revolution
- Great Demand for Resources and Geologists
Discovery of the origin of coal (1830):
- Formed in situ from plant debris growing in swamps
- Confirmed by discovery of in situ lithified tree trunk in coal seams
o >}Pv[]v^ÁvUto
One of the first Geological Society in 1807
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