The Phantom Science: How Geology Created

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The Phantom Science How Geology Created the
Amazing Natural Resources of Central Texas
Don Beaumont
Part 2
Texas Master Naturalists Land of Good Water
Chapter March 23, 2010
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Collision Mountains
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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
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Young Cretaceous 70 million years ago Austin and
Taylor shaly limestone time
In summary the Cretaceous limestones of Texas
Thick Austin Taylor muddy limestones
Beginning of Mississippi River System 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
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Cretaceous Age Limestones of Central Texas
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.
Weather into Farming Soils
Weather into Grazing Soils
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60 million years ago Paleocene Time
Five Geologic Events that Shaped
Human History
3. Weathering produces soils that are a
function of rock type
Coal Swamps
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Five Geologic Events that Shaped
Human History

• 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 earths rocky crust.
What are the products of weathering?
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Weathering Destruction of
rocks which creates soil rock debris
WEATHERING How is it done?
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WEATHERING How is it done?
Water!!!
Sun Light
Heating and Cooling
Acids
TIME
Lets see how weathering affects our Cretaceous
limestones
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Geologic Map of Texas
Upper K
Paleocene
Lower K
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?
A geologic map shows the rocks by age
below soils and vegetation
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Reef Environments Limestone Facies
Reef
Shells
How did these unconsolidated sea shell beds get
to be the rocks shown on the Texas Geologic Map?
Shell debris
Shell mud
Environments
Facies
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Burial Creating Limestone from Shells and
Shell Debris
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Shell beds buried to a depth of 3000 feet
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Shell beds buried to 7000 to 10000 feet below sea
level Now a limestone with fossils rather than
shells
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Erosion
Limestone bed uplifted to the surface of
weathering and erosion
And adding the names of our limestones we
get the following cross section
Uplift
Now add in the layers below and above the one
shown here and you get todays configuration
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Deposition and Burial before Uplift and
Erosion
Tertiary
Younger Cretaceous
Older Cretaceous
Then after Uplift and Erosion
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Cretaceous Rocks Today Outcrop Subsurface
Outcrop
Outcrop
Subsurface
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Cretaceous (K) Outcrop in Texas
Upper K
Lower 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.
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Grand Prairies
Blackland Prairies
Edwards Plateau
Soils are produced by weathering of bedrock
and the decay of vegetation
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Limestones of the Edwards Plateau, Grand,
Blackland Prairies
Taylor
Austin
Edwards
Glen Rose
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Bedrock Outcrops Vegetational Provinces
Bedrock Map
Vegetational Map
Area of older limestones
Area of older limestones
Younger K
Farming Land thick Soils
Older K
Grazing Land thin Soils
A Closer Look at Central Texas
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Geologic Map Central Texas
Glen Rose Edwards Clay-free Limestones
Austin Taylor Clay Limestones
Weather to produce Thin Grazing Soils
Georgetown
The Broader Picture
Weather to produce Thick Farming Soils
Round Rock
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Area Where Weathering Produces Thin Grazing Soils
Grand Prairies
Area of previous slide
Edwards Plateau
Now lets look at the Blackland Prairies
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Georgetown
Williamson County
Taylor
Blackland Prairies
Round Rock
Young Cretaceous Limestones Williamson Co
Blackland Prairies Black Waxy Soils
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Georgetown
Taylor
Blackland Prairies
Taylor Shaly Limestone
Thick Farming Soils
Round Rock
Austin Shaly Limestone
An Additional Element
Natural Wonders of Williamson County Blackland
Prairies Black Waxy Soils
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Natural Wonders of Williamson Co.
The Black Waxy

Weather into Black Waxy Soils
Recent River Flood Plains on hill-tops!
A Satellite View
Cretaceous Taylor Shaly Limestone
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A Satellite View
Austin Shaly Limestone
Edwards Pure Limestone
Sun City
And an Even Broader View
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A Satellite View
Austin Shaly Limestone
Sun City
And an Even Broader View
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A Satellite View
Sun City
Austin Shaly Limestone
Taylor Shaly Limestone
Finally, Up Close
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Finally, Up Close
Taylor Shaly Limestone
Austin Shaly Limestone
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Farm Soils from Taylor Shaly Limestone
Back to the Five Geologic Events that Shaped
Human History
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Five Geologic Events that Shaped
Human History

• 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
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Erosion Created Topography of Texas
Plateaus
Erosion Exposed Natural Resources that Shaped
Human History
Coastal Plains Flood Plains
Mountains
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Erosion Exposed Natural Resources that Shaped
Human History
The Oil and Gas Fields of Texas
Iron , coal , and oil exposed by
erosion in Texas
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The Oil and Gas Fields of Texas
The Water Resources of Texas
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The Water Resources of Texas
And Finally, Geological Event 5
Glaciation
Erosion brings them close to the surface where
they are recharged with rain water
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Five Geologic Events that Shaped
Human History

• 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 earths surface Example
Natural Resources of Africa
Event 5. Continental Glaciation dictates where
early farming civilizations develop
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Continental Glaciation Shapes Early Civilizations
Hostile Glacial Climate
Tropics
Glaciation provides the land bridge from Asia to
North America and the corridor to Texas
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The Land Bridge from Asia to North
America
The World-wide Spread of Humans
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Homo sapiens
Homo neanderthalensis
Homo rhodesiensis
Homo erectus
Homo Antecessor/ mauritanicus
Homo ergaster
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Thanks for the Memories