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Vagabonds & Sojourners Tramping Geology: The Appalachian Mountains Session 2: First Nation People Arrive & Explore the Southern Appalachian Mountains Where did First People come from? But first, geology in the news Extraction begun of lithium, magnesium, & copper from very hot brines used to generate electricity in the Salton Sea of southern California Lithium and magnesium are important industrial raw materials in short supply in the USA The Canadian-USA oil pipeline Bringing oil from the Canadian tar sands to mid-America Unhappy “campers” in the exploration for Marcellus shale gas in New York state Unhappy “campers” in the exploration for Marcellus shale gas in New York Exploration leases signed 5 years ago are being extended under forced majeure without increased compensation equivalent to compensation being offered today for new leases A new book you may or may not want to read The Quest: what’s in our energy future and our options Let’s try serious conservation of our energy resources From Patricia Windsor From Patricia Windsor Government bureaucracy is delaying the creation of a large number of new, high pay jobs by delaying permits to drill in the USA offshore, New York state, etc. What’s not mentioned is the need now to begin the recruiting and training of 1,000’s of new geologists and engineers to handle the phenomenal growth of the oil and gas industry in the next 40 years Some news from Africa Geology in the News Diagram up close Human language began far from central Africa where fossils indicate humans evolved Rift Valley Area Advent of humans? Now recall from last week; where did First Nation Peoples in North America come from? Human migration out of Africa Last continental glacier: North America Last continental glacier: Eurasia Human land path Several current theories on the migration routes Out of Africa 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 15,000 years ago What might have been the environment 15,000 years ago in Appalachia? Last Four Ice Ages Homo sapiens Focus on the time of Homo sapiens Looking at the last glacial period: events favoring migration into North America Possible migration times of early humans into North America: 35,000 & 15,000 years ago Last glacial period 35,000 years ago glacial recession 15,000 years ago pre-Clovis The big picture Human History Time Line: aka Recent Geologic Time Line One Million Years Ago Now Now Now recall the possible Lastroutes Ice Age to Appalachia Human history AD Possible Intra-glaciation Migration of Humans from Asia to North America 15,000 years ago 35,000 years ago mid-late glacial period What might have the Canadian portion of the migration routes looked like? 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 Time for a little more geology What made the valleys & ridges? Marine Limestones, & Shales: HowSandstones, did these marine rocks get here, The rocks of the Valley & Ridge Province miles from the ocean? rocks made from sediments deposited Let’soceans go backalong to ourcontinental Central Texas model in the margins of making rocks from sediments Let’s follow the erosional debris Deeply buried layers are uplifted, weathered and the debris is moved to the oceans 43 River Erosion in Central Texas Land surface 65 million years ago Present day Land surface Sedimentary rocks 145 to 65 million years old on continental crust (metamorphic in igneous rocks) What is a geosyncline? What is a Geosyncline? Answer: A thick (1000’s of feet) accumulation of rock debris in the ocean at the continental margin Debris brought to the ocean by rivers and spread along the coast by ocean currents Geosyncline Example: Ocean river debris A modern example of a geosyncline: The Gulf of Mexico geosyncline Example of a Geosyncline: Gulf of Mexico 1. Integration of the debris of several rivers 2. Accumulation of thick layers of debris Sandstone Reservoir Rocks Gulf of Mexico Geosyncline 65,000 feet thick Subsurface Cross Sections Gulf of Mexico Geosyncline Shale Source Rocks Gulf of Mexico Mature Source Rocks 2. Accumulation of thick layers of debris What is the “fate” of all geosynclines? What is the “fate” of all geosynclines? Sediments in ocean at the margin of the continent Building a new mountain range by crushing & melting the sedimentary rocks creating metamorphic & igneous rocks Where have sedimentary rocks in North America been converted to metamorphic & igneous rocks? The Appalachian Geosynclinal Model The Fate of Thick Debris in the Sea Rocks at the surface today along Continental Margins The Appalachian geosyncline has been welded back into the North American continent as a mountain range Debris of the Appalachia geosyncline turned into the Appalachian Mountains Here’s how mountain building works Mountain Building Appalachian Example Mountains welded onto continent Appalachian Geosyncline 250 million years ago Illinois Limestones Ohio Pennsylvania Pennsylvania Virginia Virginia Sandstones Sandstones and Crushed Melted Shales Shales Rocks = Mountains Purple “mountains” = metamorphic rocks Red “mountains” = igneous rocks Mountain building produces two types of igneous rocks Today’s Gulf of Valencia Geosyncline Ocean Granite: continental crust Pre-Cambrian granites Mountain building: Partial melting stage Schists Gneiss Slate Ocean Granite: continental crust Pre-Cambrian granites Then complete rock melting Mountain building: Complete melting stage Rhyolite lavas Black basalt lavas Granites at depth Gabbros at depth Then complete rock melting Schist Rhyolite Basalt Let’s put it all together from the creation of the earth, 4.8 billion years ago Gneiss Granite Gabbro Our “earth” 4.8 billion years ago Hot cloud of gas & dust Hot cloud: Cools forming rocky lithosphere Hot-gas cloud cools: core, mantle, & crust crust mantle core As the still molten crust forms, it separated into continental crust & oceanic crust Granite Molten mantle Granite Basalt Continental crust congealing on molten mantle Oceanic Crust congealed Granite Granite Granite Steam from the cooling ocenic crust Molten mantle forms the oceans Granite Basalt Oceans Oceanic Crust congealed Hot gasses cool to with form sunlight the atmosphere Rain combined begin Granite the weathering and erosion of Granite the continental crust Erosional debris from the continents is moved by rivers to the continental margins forming geosynclines Granite Molten mantle Granite Basalt When geosynclines have been filled to “capacity” they are crushed & melted into mountain ranges Granite Granite Mountain Building Granite Molten mantle Granite How are the rock types arranged in all this? Basalt Granite Granite What rocks are produced by these Geosyncline geologic processes? Sandstone Continental Crust Granite: coarse grained light color light weight Mountains Marble Schist Gneiss Rhyolite Granite Basalt Mantle Gabbro: coarse grained black heavy weight Shale Limestone Oceanic Crust Basalt: no grains black heavy weight Let’s look more closely at rocks Rocks are made of minerals Minerals are naturally occurring compounds of elements (remember the periodic table from chemistry) Most common minerals: clays (half a dozen): make shale feldspars (half a dozen): make igneous & metamorphic rocks quartz: make sandstones, in granite & rhyolite Now big picture calcite: makethe limestones Ancient Mountains of North America Appalachian Mountains A schematic diagram of North America Hypothetical Diagram: Ages of Ancient Mountains of the Continental Crust Back to the Blue Ridge Mountains of Appalachia Crust Crust Crust Original Crust 2B 3B Crust: 4.8 B 3.5 B 1.4 B Volume of continental crust appears constant over time. Therefore, original continental crust might have been much thicker that later crust as the various mountains were created by compressing their corresponding geosynclines The Blue Ridge Mountains of Appalachia What type of rocks did they find in mountains? What type of rocks did they find in mountains? Metamorphic Rocks: sedimentary rocks buried to great depth, squeezed , crushed, & partially melted Metamorphic Rocks of the Blue Ridge Schists What didGneisses first Nation People find east of the Blue Ridge Mountains in the Piedmont foothills? Geological Provinces: Central & Southern Appalachians Pennsylvania Valleys & Ridges of ss, sh, & ls Ohio Mountains of metamorphic rocks Kentucky Tennessee Virginia Foothills of igneous rocks North Carolina What do the igneous foothills look like? Geological Provinces: Central & Southern Appalachians Mt. Airy granite North Carolina Mt. Airy area up close Blue Ridge Mountains Piedmont foothills Mt. Airy granite area hills Do we find basalts in the southern Appalachian Mountains? Two Geologic Processes that shape the Earth’s Surface Weathering Erosion Erosion Weathering: Natural destruction of the rocky continental crust Weathering: Natural destruction of the rocky continental crust Causes: sun rain plants wind TIME WEATHERING: Destroys Rocks Creates: 1. rock debris 2. soils (rock debris + decaying plants) Produces: unique environments Rock “Debris” 1. quartz sand 2. muds (clays) 3. calcium carbonate solutions Best farming soils: thick clay debris in river flood plains in Temperate Climate Zones Soils & rock debris are carried away by erosion Erosion: Natural process of moving rock debris to the oceans at the continental margins Products of erosion: topographies rock outcrops river flood plains geosynclines What causes erosion? Erosion: Causes Moving the weathered rock debris to the sea by: 1. gravity!!! It all goes down hill 2. water: brooks streams rivers Erosion: 1. produces topography 2. exposes different rocks at the earth’s surface 3. creates river flood plains erosional 3. The creates geosynclinestopography of the Southern Appalachians Mountains Weathering & Erosion Create the Topography of the Appalachians Appalachian Erosional Topography Detail look at the area of the black box: Great Valley area of Central Pennsylvania Next Week The Great Valley & Blue Ridge and the Last Continental Glacier Tramping from Alabama to Pennsylvania The last continental glacier controls everything