The Phantom Science: How Geology Created the Amazing Natural Resources of Central Texas Don Beaumont Texas Master Naturalists Land of Good Water Chapter March 23, 2010 Geological Resources Earth’s crammed with heaven, And every common bush afire with God; But only he who sees takes off his shoes, The rest sit round it and pluck blackberries. Elizabeth Barrett Browning

Geological Resources Rivers and River Flood Plains Farming soils Hills and Valleys Grazing & farming soils Rivers, lakes, & ground water Water Rocks Iron, coal, oil & gas, and uranium How does geology provide these resources?

How does geology create natural resources? Four geological processes Five geological events 1. Continental drift 2. Plate tectonics 3. Weathering 4. Erosion 1. Continental Drift positions the continents 2. Plate Tectonics shapes the continents 3. Weathering makes soils 5. Glaciers determine human distribution 4. Erosion creates topography & exposes ores Four Geological Processes 1. Continental Drift

Continental Drift The slow movement of the crustal plates over the face of the earth

//detrab/Tektonika/litosfera2.htm Continental Drift: Last 250 million years Present Day 250 million years ago Four Geological Processes 2. Plate Tectonics

2. Plate Tectonics The deforming of continents as they move & when they collide Types of deformation: warping = major river systems crushing & melting = mountain ranges

Down warp Crushing & melting 2. Plate Tectonics Plate motion = warping = major rivers Plate collision = crushing & melting = mountain ranges Four Geological Processes 3. Weathering

The natural destruction of the surface of the earth’s rocky crust Weathering produces rock debris: 1. Clays combine with decaying organic matter to make soils 2. Clays, Ca solutions, & sand are carried by rivers to the continental margins Four Geological Processes 3. Weathering Bed Rock (soils) of Texas

Bed Rock (soils) of Texas Each rock (color) weathers into a unique soil

Grand Prairies Edwards Plateau BlacklandPrairies Vegetational Areas of Texas Similar soils produce these vegetational areas Williamson County Four Geological Processes 4. Erosion

4. Erosion The transport of weathered debris by water to the continental margins Erosion: 1. creates topography 2. exposes ores and oil at or near the earth’s surface 3. creates river flood plains Erosion Created Topography of Texas

Erosion Created Topography of Texas Mountains Plateaus Coastal Plains & Flood Plains Erosion Exposed Natural Resources that Shaped Human History

Iron, coal, and oil exposed by erosion in Texas Erosion Exposed Natural Resources that Shaped Human History Flood Plains Created by Rivers Carrying Clays & Sand to the Ocean

M a j o r r i v e r f l o o d p l a i n s Flood Plains Created by Rivers Carrying Clays & Sand to the Ocean Five Geologic Events that Shaped Human History

How does geology create natural resources? Four geological processes Five geological events that shaped the history of Texas 1. Continental drift 2. Plate tectonics 3. Weathering 4. Erosion 1. Continental Drift positions our continent 2. Plate Tectonics shapes our continent 3. Weathering makes our soils 5. Glaciers determine human distribution 4. Erosion creates our topography & exposes our ores 1. Continental Drift positions our continent

Five Geologic Events that Shaped Human History Continental Drift positioned Central Texas: A. determining when humans would arrive B. creates two limestones rocks: aquifers & springs Determining the migration path of humans

Western Hemisphere Eastern Hemisphere How has continental drift shaped human history? Created the Western and Eastern Hemispheres Critical to the migration of humans out of Africa Next: How Plate Tectonics shaped human history?

Five Geologic Events that Shaped Human History 1.Continental Drift shapes & positions the continents Migration path of humans created 2. Plate Tectonics shapes the continents: A. Determines location of early nations B. Creates new rivers in Texas & muddy limestones = good farming soils C. Creates sandstone/shale rocks in Texas with coal 2. Plate Tectonics shapes the continents: A. Determines location of early nations

Geological Event # 2: 6000 mile mountain range created by Africa & India colliding with Eurasia Yellow Yangtze Ganges Tigris Euphrates Nile Indus Ideal trend for the early development of large scale farming civilizations Conclusions: Early civilization grew in: 1. the Northern Temperate Zone 2. major river flood plains Why no major nations in Texas?

Major river floodplains Why no major nations in this Temperate Zone Flood Plain? Flood Plains Created by Rivers Carrying Clays & Sand to the Ocean Area adversely affected by the melting of the most recent continental glacier: 1. flooded with debris choked melt-water 2. hostile cold climate Plate Tectonics creates two limestones with aquifers, caves, and springs in Central Texas

Five Geologic Events that Shaped Human History Continental Drift positioned Central Texas: A. determining when humans would arrive B. Plate Tectonics creates two limestones with aquifers, caves, and springs in Central Texas

Mid-Cretaceous: 90 million years ago Edwards Limestone Time Edwards Limestone Time Beach in southern Oklahoma So what is a limestone? No nearby rivers with mud & silt = pure limestone Area of Edwards Limestone Shallow water Edwards limestones forming in Texas Tropical Climate Zone

Typical Limestones in Sun City, Texas A dense limestone, no obvious shells, made of lime mud Just what is a limestone? A limestone reef composed of rudists and many other shell fish.

Shells & Shell Debris (majority marine) Limestones (CaCO3) Mineral: calcite Limestones are Rocks Made of Sea Shells Back to the Edwards Limestone formed in an ancient, tropical, island paradise

Paleogeographic Map: Gulf of Mexico Florida Texas Sun City Extent of the Edwards Limestone A modern example: the Great Barrier Reef of Australia

The Great Barrier Reef of Australia A modern equivalent of the Edwards Great Barrier Reef Shallow Ocean Environments = Limestone Facies

Reef & Reef Mound Shells Shell Debris Shell mud Composite A Typical Limestone Formation

Cartoon of a Typical Limestone Formation Scale: beds from inches thick to 10’s of feet thick Each bed contains one or more environments Remember the Rudist Reef Rocks?

What is a rudist and how do they form reefs?

Rudist forming Reefs: Typical of Cretaceous Limestones Edwards Limestone has thick (up to 50 feet thick) layers (beds) composed of RUDIST REEFS and REEF DEBRIS MOUNDS Rudists are Horn-shaped Sea Shells Rudists grow in colonies (reefs) Rudist shells are very fragile so they are often destroyed by weathering leaving a cone shaped hole

A Rudist Reef Rock Outcrop Each hole was occupied by a rudist shell fish The cavities in reef limestones often make: 1.good aquifers, 2. springs, 3. caves.

Lower Cretaceous Edwards Limestone Reef Blue Hole City Park

Edwards Limestone Reefs and Caves I-35 Access Road Cut at Leander Road Reef water filled aquifer spring

A Cave in a Limestone Layer Cave formed by ground water solution of the Limestone Let’s look at a cartoon of a limestone cave

Block Diagram of Mammoth Cave Back to the Five Geologic Events that Shaped Human History (esp. in Texas)

Five Geologic Events that Shaped Human History 1.Continental Drift shapes & positions the continents Migration path of humans created 2. Plate Tectonics shapes the continents: How are continents shaped? 1. mountain building 2. broad down-warping 3. broad up-warping 1. mountain building

Creating a Geologic Model for Mountain Building Mountain Building: When two crustal plates collide

Crustal Plates: Both Oceanic & Continental Continents are carried on their crustal plate

Plate Collision

Mountain Building Plate Tectonic Theory Three Types of Plate Collisions Continent Mountains Oceanic Plate Continent Oceanic Plate Oceanic Plate