Transcript File
Tramping Geology through the Appalachians Original music by Bob Blackshear: Nashville recording artist Song writer and singer Sun City Resident Vagabonds & Sojourners Tramping Geology: The Appalachian Mountains Session 1: Getting Started An Overview of the Next 6 Weeks Remember our field trip, Nov. 3rd And now, Geology in the News Geology in the News Next, diamonds reveal geology of the deep “earth furnace” that generates many of our natural metallic resources New York Times, Sept.15, 2011 Geology in the News Continent Oceanic crust And, China turns out our “green” lights, at least for a while New York Times, Sept.16, 2011 Mantle plume (hot spot) Geology in the News Now to “playing in the sand pile” in McCulloch County, Texas New YorkAustin Times, Sept.16,statesman, 2011 American 9-18-11 Geology in the News McCullough County Austin Up close McCullough County Sand quarries McCulloch County The big picture: why sand here? Is the favorable sand elsewhere? North America 505 million years ago Ancient beach sands McCullough County Now to an earthquake in Himalayas Geology in the News Tibet-China 6.9 India Geology in the News Geology in the News Nile geosyncline gas prone Geology in the News Cyprus Offshore territory Nile geosyncline gas prone Back to the Western Hemisphere Expensive production from deep water (6,000 feet+) Brazil and Canadian tar sands forecast to provide oil to replace diminishing resources in Mexico and Venezuela. Geology in the News Computer modeling of oil & gas reservoirs using seismic, drilling, production, and conceptual data Now, back to the Appalachians Vagabonds & Sojourners in the Appalachians Six Sessions As we follow the Great Valley we’ll: 1. explore the heart of the Appalachians 2. note to economic resources of the interior 3. relate human history to the last great continental glacier Return to NC & follow the Great Valley through VA, WV, MD, PA, NY, CT, & VT into Canada Where are the lands of the Sojourners? Follow the Blue Ridge to Georgia & Alabama Begin in North Carolina Blue Ridge Mts The Lands of the Sojourners 5 1 0 14 3 1 4 14 Sandi’s first 4 geology field trip: Wisconsin Dells age 6 months 2 Back to Session 1 11 7 5 17 Vagabonds & Sojourners Tramping Geology: The Appalachian Mountains Session 1: Getting Started What is a geologic mountain? What is a geologic mountain? Rocks deformed by the collision of two plates of the earth’s crust Mountains grow to great heights & are gradually destroyed by weathering & erosion Mountain Classification Youthful Mountains: Washington State Mature Mountains: Mount Mitchell, North Carolina Old Age Mountains: Granville Range Llano County, Texas What is a geologic mountain? Rocks deformed by the collision of two plates of the earth’s crust Mountains grow to great heights & are gradually destroyed by weathering & erosion Mountains are composed of folded, faulted, and melted rocks Folds, faults, and melted rocks Valley & Ridge Appalachian Geologic Province Folded & faulted rock layers What is a geologic mountain? Rocks deformed by the collision of two plates of the earth’s crust Mountains grow to great heights & are gradually destroyed by weathering & erosion Mountains are composed of folded, faulted, and melted rocks Mountain building exposes different rock types at the surface Folds, faults, and melted rocks Valley & Ridge Folded & faulted rock layers What type of rocks do we have in the Valley & Ridge Province? A Land of Long Ridges and Valleys What made the ridges & valleys? Sedimentary rocks of all kinds What made the valleys & ridges? Sandstones, Limestones, & Shales: rocks of the Valley & Ridgedeposited Province rocks made from sediments in the oceans along continental margins Sediments Rocks Sediments accumulate in oceans at continental margins They accumulate in layers, one on top of another They are composed of: sand, mud, &/or sea shells How do these sediments become rocks? Creating the Three Sedimentary Rock Types Limestones: made from sea shells Sandstones: made from “ beach” sands Shales: made from mud and silt A Simple Example 37 Cross Section showing different Sediment layers Shell layer Mud layer Sand layer How do these soft sediments become solid rocks? Let’s follow one shell layer as it becomes a limestone How are Solid Rocks Formed? Example: Limestones in Williamson County Edwards started out as a “shell” layer 400 feet thick What happened next? 39 Layer after layer of sediment deposited on top of Edwards “shell” layer Burial, compaction and dewatering. 40 What happens to newly formed rocks? 41 What did we find east of the Valley & Ridge Province? Uplift brings to the surface natural resources created at great depth: e.g. metals, coal, oil, etc Deeply buried Edwards Limestone layer Uplifted, Weathered, and Eroded 42 What type of rocks do we find in these mountains? The Blue Ridge Mountains What type of rocks do we find in the Blue Ridge Mountains? Metamorphic Rocks: sedimentary rocks buried to great depth, squeezed , crushed, & partially melted Parallel to & east of the Blue Ridge Origin of metamorphic rock types: is the sandstone Piedmont= geological province quartzite limestone = marble shale = slate sandstone + shale = schist = gneiss** ** most common metamorphic rocks rocks of the Blue Ridge Mountains Geologic Provinces of North Carolina Great Smoky Mountains 600 million year old sandstones & shales The Piedmont geologic province Igneous & metamorphic rocks What is an igneous rock? What is an igneous rock? Remember that Metamorphic Rocks are: sedimentary rocks buried to great depth, squeezed , crushed, & partially melted Origin of metamorphic rocks: sandstone = quartzite basalt shale = slate limestone = marble granite An igneous rock one formed by complete Where we find rocks? meltingdo & cooling of aigneous pre-existing rock Let’s at the big rocks: picture Two look principle igneous granites-rhyolites & basalts-gabbros The Solid Earth Rocky Crust Plastic Rocky Upper Mantle Focus on the rocky crust The Earth’s Rocky Crust: Two Types Oceanic Crust: 5 miles thick under the oceans: basalt Continental Crust: 20 to 50 miles thick makes the continents: granite Let’s look at the Oceanic Crust The Mantle: “Molten” (plastic) rock below the crusts The Earth’s Oceanic Crust The Rocky top of the Mantle Ocean Oceanic Crust: basalt 5 miles thick A world view Oceanic OceanicCrust: Crust: dark dark colored colored rocks rocks dense dense rocky mantlebasalt rocky toptop of of thethe mantle: All the dark blue are basalt All the dark blue are basalt Next the Continental Crust The Earth’s Continental Crust “Floating” on the Mantle Oceanic Crust Continental Crust A world view Continental Crust: light colored rocks less dense than oceanic crust “floats” on the mantle: granite How “thick” is North America compared to the whole earth? Our Earth Radius = 4000 miles Interior of Our Earth How thick is a continent? 8000 miles 4000 miles = radius How thick is a continent? 2000 miles How thick is a continent? 1000 miles How thick is a continent? 500 miles How thick is a continent? 100 miles thick 500 1000 2000 Just one half to one quarter as thick as this orange line 4000 8000 How far does North extend? A continent is only 25America to 50 miles thick! How far does North America extend? North Pole Cut the earth North America in half through the poles Center of the earth Equator Conclusion: continents are a thin West veneer on the surface of our earth Yetearth’s theyrocky move “plates” overmajor The crustas is broken into seven South Africa separate plates number through of small plates the face ofplus thea earth time South Pole The Earth’s Crustal Plates Today Crustal plates move during geologic time North American Plate Pacific Plate Eurasian PlateRecent earthquake African Plate Evidence of plate motion Plate motion in geologic time: 1. moves continents into different climate zones and E. A. Keller, 1996, Environmental Geology 2. creates mountains whenFrom the plates collide The Earth’s Earthquakes and Volcanoes Evidence of Plate Motion Today Recent earthquakes How were the plates configured when the Appalachian Mountains were created by plate collision? From E. A. Keller, 1996, Environmental Geology 270 million years ago: (Permian Period) The Appalachian Mountains have just been formed by the collision of North America with South America-Africa North America Let’s look at a more detailed map South America Africa North American plate A lookto atthe the Appalachian collision of crustal plates Now Mountains Check “hidden” figs. 23 thru 28 Plate collision Appalachian Mountains South American-African plate European plate Tramping Geology through the Appalachians Original music by Bob Blackshear: Nashville recording artist Song writer and singer Sun City Resident Geology in the News Tibet-China 6.9 India Geology in the News Geology in the News Nile geosyncline gas prone Geology in the News Nile geosyncline gas prone Cyprus Offshore territory Nile geosyncline gas prone Expensive production from deep water (6,000 feet+) Brazil and Canadian tar sands forecast to provide oil to replace diminishing resources in Mexico and Venezuela. Geology in the News Computer modeling of oil & gas reservoirs using seismic, drilling, production, and conceptual data Now back to the Appalachians But first, a little about Geologic Time As we define the history and geology of the Appalachian Mountains we’ll also focus on how human history was shaped by the geological events that created these mountains Geologic Time Scale Appalachian Mountains formed Human History Our focus: last 570 million years Geologic Time: Last 570 Million Years Appalachian Mountains 570,000,000 years Last 5 Million Years The time of us “humans” Geologic Time Line: last 5 million years “Humanoid & Humanid” Fossil History Now Oldest Humanoids Kenya 1970are Where Volcanic mud Footprints 1978 earlyTanzania, human fossils found? Current Known Earliest Humanoid Fossils Hot Spots under Africa today General Area of Oldest Human ancestors A closer A look at the view last 5 million years closer From: Ron Redfern, 2000, Origins Today You & Me 1 million years ago 2 million years ago Added NY Times 9-11 3 million years ago A closer look: the last 1 million years 4 million years ago Homo erectus & Homo sapiens Columbia University Lamont Geol Inst 2011 Homo sapiens Homo neanderthalensis Times of Continental Glaciation: Northern Hemisphere Homo rhodesiensis Focus on Homo sapiens Homo Antecessor/ mauritanicus Homo ergaster Homo erectus Awesome Humans: reasoningHomo Fossil Record: The 1.Current Expressed in language 2. conscience Last 300,000 years 3. adapt to any environment 4. migrated worldwide in 80,000 years Time of Written World History Last ice age Human history time line http://en.wikipedia.org/wiki/File:Humanevolutionchart.png Human History Time Line: aka Recent Geologic Time Line One Million Years Ago Now Next, Eurasia 10,000 years ago Now Last Ice Age AD human history BC Other views of human migration Last continental glacier: North America Last continental glacier: Eurasia Human land path Nile River Rift Valleys Migration of Humans into Eurasia Possible Migration Route of Humans into the Western Hemisphere More specific routes Alternate route current theory: Asia to North America by sea The awesome challenge of migrating by sea Alternate route current theory: Asia to North America by sea The awesome challenge of migrating by sea Early human artifacts in the vicinity of the Appalachian Mountains Evidence of early humans in the Appalachians Pre-Clovis artifact sites But when did they first come to North America? Might it have been while the glacier was growing rather than when it was at it maximum extent? Last Four Ice Ages Homo sapiens Looking at the last glacial period Possible migration of early humans into North America 35, 000 years ago Last glacial period 35,000 years ago glacial recession 15,000 years ago pre-Clovis The big picture Possible Intra-glaciation Migration of Humans from Asia to North America 15,000 years ago 35,000 years ago mid-late glacial period What did early humans find on their way to Appalachia? Possible drainage challenges of migration during a glacial recession What might the Canadian portion of the migration route looked like? North South Glacier Cold hostile climate! Possible drainage challenges of migration during a glacial recession What did First Nation People find when they finally got to Appalachia? Melting glacier Maximum extent of last glacier Following the rivers, staying away from the melting glacier What did Appalachia look like as First Nation People approached it from the west? A Land of Long Ridges and Valleys What made the ridges & valleys? And east of this region Blue Ridge Mountains Valley & Ridge province Next Week Next Week First Nation People arrive and explore Southern Appalachia