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Senior University Fall 2008. The Phantom Science. Geology, the Science that Shapes Human History. From the Flint Arrow Heads in the Stone Age to Gasoline at $15.00 a Gallon in Our Lifetime. Session 1: The Stone Age. The mind seems to grow giddy by looking
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Senior University Fall 2008 The Phantom Science Geology, the Science that Shapes Human History From the Flint Arrow Heads in the Stone Age to Gasoline at $15.00 a Gallon in Our Lifetime Session 1: The Stone Age
The mind seems to grow giddy by looking so far into the abyss of time Jay Playfair, 1805 The Phantom Science Session 1 From pre-history to the Stone Age Science: Natural facts discovered by experiment and the testing of hypotheses
Humans are creatures who comprehend things they cannot see and believe in things they can not comprehend William Howells
Our Next Field Trip Senior University: One Day Geology Field Trip Thursday November. 6, 2008 :Water, Oil, and Coal: Our Amazing Treasures in Williamson Co!
Our Next Field Trip Anyone for Rock Jumping?
References References From: Ron Blakey, 2000 with permission From E. A. Keller, 1996, Environmental Geology From: S.M. Stanley,1999, Earth System History From: Hammond Atlas, 1972 From: Ron Redfern, 2000, Origins Jared Diamond: Collapse: How Societies Choose to Fall or Succeed Human History: What shaped it from the beginning? Jared Diamond: Collapse: Guns, Gems, and Steel: Grand Unified Theory of History Simon Winchester: The Map that Changed the World Bill Bryson: A Short History of Nearly Everything
Today’s Session: The 3rd Rock from the Sun Geologic conditions encountered by Stone Age Humans What shaped human history? Hypothetical Examples from Central Texas
Human History: What shaped it from the beginning? Events Great Leaders Some recent books on the subject Geography God(s) Geology?
Book by Dr. Jared Diamond, geographer, UCLA Guns, Germs, and Steel: Grand Unified Theory of History Factors Determining Prevailing Societies raw materials (ores) crops(soils & rock outcrops) climate trade routes shore lines Another Book by Diamond
Book by Dr. Jared Diamond, geographer, UCLA Collapse: How Societies Choose to Fall or Succeed Societies doomed by geography (Geology) fragile ecosystems climate change hostile neighbors bad decisions Finally: Another Recent Book
How Trade Shaped World History The Scientific Method In this course I’ll try to convince you that geology & “geologists” are the principal enablers of human history
The Scientific Method Good Old Common Sense 1. Observe and Record Information 2. Imagine an Explanation(s) Here’s how I propose it works 3. Test our Explanation(s) 4. Peers review our Conclusion(s) Explanation to be tested: 1. Geology has been practiced from the beginning of human history 2. Geology shapes human history
Hypothesis: Geology Shaped “Nations” from the Beginning Create a: Empire Nation State Clan Tribe Make Tools & Weapons Mine Ore & Fuel Gather Ore & Fuel Smelt Metals Steel Iron Bronze Stone (flint) Steel Iron Bronze Stone (flint) Iron Ore Coal Copper/tin Flint Obsidian Iron Ore Coal Copper/tin Wood Flint Obsidian Locate the Ore & Fuel “Beg, Borrow, or Steal”
Two Geologies 1. The Earth’s Conditions & Processes Geology & Human Knowledge 2. Our Knowledge of Earth’s Conditions & Processes Unrecorded: before 1785 AD Written: since 1785 AD
Religion = Explaining Reality Art = Representing Reality Philosophy = Defining Reality Now, the 3rd Rock from the Sun History = Oral & Written Human Records Biology = Living things Geology = 3rd Rocky Ball from Sun Astronomy = Universe & Solar System Physics & Chemistry = Matter & Energy
The Earth’s rocky crust & topography Geological Map of USA showing different age rocks Our Hypothesis: Each rock will shape history in a unique way First, let’s Review the rock types that make up the Earths rocky crust
The 3rd Rocky Ball from the Sun Crust Upper Mantle Another Representation of our Earth Diameter = 4000 miles What is an Igneous Rock? Earth’s Upper Mantle=coarse grained Igneous Rock Called Gabbro Earth’s Crust under the oceans=fine grained Igneous Rock Called Basalt
Common Igneous Rocks Granite: formed melted continental crust Cool Slowly=Light color & “weight”, crystals Rhyolite: formed melted continental crust Cool Quickly=Light color & “weight”, no crystals Basalt: formed melted oceanic crust Cool Quickly=Dark color, “heavy”, no crystals Gabbro: formed melted oceanic crust Cool Slowly=Dark color, “heavy”, crystalline
Igneous Rock Occurrences • Volcanoes: yield basalts or rhyolites • Quick cooling = no visible mineral crystals • Deep Crust: granites & gabbros • Slow cooling = visible mineral crystals Back to the Earth’s Rocks
Rocks of the Earth’s Crust Dark Blue=Basalt What do these rocks look like? Under the Deep Oceans is Fine Grained Black Basalt
Quiz Time: What do we call these rocks that have cooled from molten “rock”? Rock in Earth’s Mantel: below the Earth’s Crust Rock of the Oceanic Crust Shield Volcanoes & Flows
Rocks of the Earth’s Crust Igneous Rocks: Rocks that have been melted & cooled. What other igneous rocks are there in addition to gabbros & basalts of rocky Oceanic Crust?
Igneous Rocks make up most of the Continental Crust
The Rocky Crust of the Earth A dbeau Cross Section Most granites were formed four billion years ago when the earth was formed from hot gas & dust What other types of rocks are there in addition to igneous rocks? Granite Definition: Granite, coarse grained igneous rock making up most of the continental crust Continental Crust Oceanic Crust
Rocks of the Earth’s Crust Three Rock Types: Sedimentary Metamorphic Igneous Sedimentary Rocks
Three Sedimentary Rocks Limestones: made from sea shells Sandstones: made from beach sands Shales: made from mud and silt Where are they formed?
Sedimentary Rocks 1. Formed in layers 2. Majority formed in oceans at the margins of continents 3. Composed of debris from pre-existing rocks 4. brought to ocean by rivers How do sands, muds, and shells become solid rocks?
How are Solid Rocks Formed? Example: Limestones in Williamson County Edwards started out as a “shell” layer 400 feet thick What happened next?
Layer after layer of sediment deposited on top of Edwards “shell” layer Burial, compaction and dewatering.
Many more layers of sediment deposited on top of Edwards Edwards shells recrystalize to limestone with fossils Continued burial to depths as deep as 10,000 feet and deeper What’s next?
Uplift brings to the surface natural resources created at great depth: e.g. metals, coal,etc Deeply buried Edwards Limestone layer Uplifted, Weathered, and Eroded
Erosion in Williamson County Today More rock eroded than remain! Sun City & Lake Georgetown What’s below these Rocks?
What is a Metamorphic Rock? Igneous and Metamorphic Rocks
Metamorphic Rocks Partially Melted Rocks: Limestone=Marble Sandstone=Quartzite Shale=Slate=Schist Sandstone & Shale=Gneiss The Rock Cycle
The Rock Cycle Lava Sediments Sedimentary Rocks Magma Igneous Rocks Where are these Rocks Found? Melting Partial Melting Metamorphic Rocks
The Rocky Crust of the Earth A dbeau Cross Section Most granites were formed four billion years ago when the earth was formed from hot gas & dust Sedimentary Rocks Metamorphic Rocks Where are the Earth’s Natural Resources formed and Found? Granite Continental Crust Oceanic Crust What other types of rocks are there in addition to igneous rocks?
The Rocky Crust of the Earth A dbeau Cross Section Most granites were formed four billion years ago when the earth was formed from hot gas & dust Sedimentary Rocks Metamorphic Rocks Oil & Gas Coal Granite Metal Ores Continental Crust Oceanic Crust A Quick Summary
Summary: Origin of Rocks Oldest: Igneous rocks formed by the cooling of molten rock. Now the Fate of all Rocks: Weathering Erosion Old: Metamorphic rocks: formed by the cooling of partially molten rock Youngest: Sedimentary rocks formed by the accumulation of rock debris
The Fate of All Rocks at the Earth’s Surface: Destruction by Weathering & Erosion Weathering of: Igneous Rocks=Clays & Sand Metamorphic Rocks=Clays & Sand Sedimentary Rocks=Clays, Sand, & Calcium Solutions
The Fate of All Rocks at the Earth’s Surface: Destruction by Weathering & Erosion Erosion: Moving Weathered Debris to the Oceans at Continental Margins: Clays, Sand and Calcium Solutions
Why does Rock Weathering and Erosion Shape Human History? An Example from Central Texas Because they determine: Soils rock types & weathering Landscapes differential erosion Natural resources rock content exposed by erosion
Natural Resources and Rocks of Central Texas Iron Granite (igneous), Gneiss, & Schist (metamorphic) Coal Flint Copper Water How does Erosion expose these Natural resources of the Earth’s Crust at the surface of the Earth Zinc Farming Soils Lead Silver Water Sandstones Shales Oil & Gas Water Limestones
Carving Landscapes (topography) Destruction of the Continental Crust Geologic Processes Weathering & Erosion Destruction of rocks which creates soil & rock debris
Tributary streams Berry Creek Williams Drive Berry Creek Drainage System Responsible for the erosion that produced the hills & valleys of Sun City
Carving a Landscape Now let’s look at Erosion affecting Williamson County & Central Texas
Erosion in Williamson County Every Rock on this map erodes exposing at the surface unique Natural Resources; e.g. flint, copper tin, iron, etc. Edwards Limestone Blue Glen Rose Limestone Green Sun City Balcones Fault Austin Limestone Blue Taylor Limestone Each Rock on this map weathers to a unique Soil Let’s see if a cross section will help visualize this situation Wilcox Sandstone Geological Map shows Rocks at the surface
Cross Section: Williamson Co. Erosion Sun City & Lake Georgetown City of Georgetown Eroded Rocks Large Scale Erosion: USA Landscapes (topography)
A Stone Age Nation here would have metallic ores to make weapons of conquest Geologic Map Texas Surface Rocks: Age & Type A Stone Age Nation Here would have early farming Geologic Provinces of Texas Each could produce a different Stone Age Clan or Tribe Integrating soil and topography produces these unique provinces Each “color” produces a unique soil & Landscape