Presentation on theme: "The Phantom Science: How Geology Created The Phantom Science: How Geology Created the Amazing Natural Resources of Central Texas the Amazing Natural Resources."— Presentation transcript:
The Phantom Science: How Geology Created The Phantom Science: How Geology Created the Amazing Natural Resources of Central Texas the Amazing Natural Resources of Central Texas Don Beaumont Texas Master Naturalists Land of Good Water Chapter March 23, 2010 Part 2.
Rising Mountains create broad down-warping that creates major rivers drainage areas Mississippi River drainage area Now applying this to the geologic history of Texas
Young Cretaceous: 70 million years ago Austin and Taylor shaly limestone time Thick Austin & Taylor muddy limestones Beginning of Mississippi River System bringing mud & sand into the Gulf of Mexico bringing mud & sand into the Gulf of Mexico 70 mm years age Mountain Building uplift created broad down-warping in south-central USA resulting in Mississippi River drainage system bringing mud to the limestones being formed in Central Texas In summary: the Cretaceous limestones of Texas
Cretaceous Age Limestones of Central Texas Weather into Grazing Soils Weather into Farming Soils Following the Cretaceous ever more active rivers brought mud & sand to coastal Texas that “killed” the shell fish so sandstones & shales were deposited instead of limestones.
60 million years ago: Paleocene Time Coal Swamps 3. Weathering produces soils that are a function of rock type Five Geologic Events that 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: Africa drifts into Europe = Alps India collides with Asia = Himalayas Optimum farming environment created 3. Weathering produces soils that are a function of rock type Definition: The natural process of destroying the top of the earth’s rocky crust. What are the products of weathering?
Weathering: Destruction of rocks which creates soil & rock debris WEATHERING: How is it done?
WEATHERING: How is it done? Water!!! Sun Light Heating and Cooling Acids TIME Let’s see how weathering affects our Cretaceous limestones
Geologic Map of Texas A geologic map shows the rocks by age below soils and vegetation How did the unconsolidated shell beds of the Cretaceous and sandstones & shales of the Paleocene time Periods get to be the rocks shown on this map? Lower K Upper K Paleocene
Reef Environments = Limestone Facies Environments Facies Reef Shells Shell debris Shell mud How did these unconsolidated sea shell beds get to be the rocks shown on the Texas Geologic Map?
Burial: Creating Limestone from Shells and Shell Debris
Shell beds buried to 7000 to 10000 feet below sea level Now a limestone with fossils rather than shells
Limestone bed uplifted to the surface of weathering and erosion Uplift Erosion Now add in the layers below and above the one shown here and you get today’s configuration And adding the names of “our” limestones we get the following cross section
Deposition and Burial before Uplift and Erosion Tertiary Younger Cretaceous Older Cretaceous Then after Uplift and Erosion
Cretaceous (K) Outcrop in Texas I-35 Lower K Upper K Each limestone weathers into its unique soil. Each unique soil supports a unique vegetation. Therefore, there should be a unique vegetation for the Lower K limestone outcrop & another for the Upper K limestone outcrop.
Grand Prairies Edwards Plateau BlacklandPrairies Soils are produced by weathering of bedrock and the decay of vegetation
Limestones of the Edwards Plateau, Grand, & Blackland Prairies Taylor Austin Edwards Glen Rose
Bedrock Map Vegetational Map Bedrock Outcrops & Vegetational Provinces Area of older limestones Area of older limestones Grazing Land: thin Soils Farming Land: thick Soils A Closer Look at Central Texas Older K Younger K
Georgetown Round Rock Glen Rose & Edwards Clay-free Limestones Weather to produce Thin Grazing Soils Geologic Map: Central Texas Austin & Taylor Clay Limestones Weather to produce Thick Farming Soils The Broader Picture
Area of previous slide Area Where Weathering Produces Thin Grazing Soils Edwards Plateau Grand Prairies Now let’s look at the Blackland Prairies
G e o r g e t o w n R o u n d R o c k Taylor Young Cretaceous Limestones: Williamson Co Blackland Prairies: Black Waxy Soils Blackland Prairies: Black Waxy Soils W i l l i a m s o n C o u n t y B l a c k l a n d P r a i r i e s
Georgetown Round Rock Taylor Blackland Prairies Austin Shaly Limestone Natural Wonders of Williamson County Blackland Prairies: Black Waxy Soils Blackland Prairies: Black Waxy Soils Taylor Shaly Limestone Thick Farming Soils An Additional Element
Recent River Flood Plains on hill-tops! Natural Wonders of Williamson Co. The “Black Waxy” C r e t a c e o u s T a y l o r S h a l y L i m e s t o n e Weather into Black Waxy Soils A Satellite View
Sun City Austin Shaly Limestone Edwards Pure Limestone A Satellite View And an Even Broader View
Austin Shaly Limestone A Satellite View Sun City And an Even Broader View
Austin Shaly Limestone Taylor Shaly Limestone A Satellite View Sun City Finally, Up Close
Austin Shaly Limestone Taylor Shaly Limestone Finally, Up Close
Farm Soils from Taylor Shaly Limestone Back to the Five Geologic Events that Shaped Human History
Five Geologic Events that Shaped Human History 1.Continental Drift shapes & positions the continents Migration path of humans created 2. Continental Drift & Plate Tectonics: Africa drifts into Europe = Alps India collides with Asia = Himalayas Optimum farming environment created 3.Weathering produces soils 4. Erosion creates topography and exposes ores, water, and oil at or near the surface
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 The Oil and Gas Fields of Texas
Erosion brings them close to the surface where they are recharged with rain water And Finally, Geological Event #5; Glaciation
Five Geologic Events that Shaped Human History 1.Continental Drift shapes & positions the continents Migration path of humans created 2. Continental Drift & Plate Tectonics: Africa drifts into Europe = Alps India collides with Asia = Himalayas Optimum farming environment created 3. Plate Tectonics: East Africa uplifted, rift faulted with advent of human beings 4. Weathering exposes critical ores and oil at or near the earth’s surface: Example: Natural Resources of Africa Event # 5. Continental Glaciation dictates where early farming civilizations develop
Continental Glaciation Shapes Early Civilizations Tropics Hostile Glacial Climate Glaciation provides the land bridge from Asia to North America and the corridor to Texas
The Land Bridge from Asia to North America The World-wide Spread of Humans
Homo erectus Homo Antecessor/ mauritanicus Homo rhodesiensis Homo neanderthalensis Homo ergaster Homo sapiens