|BSB directory||BSB Education||BSB lectures||BSB Mission||Patient Earth|
GeologyMore knowledge = better decisions
Geology of the Texas Hill Country|
The name for the science of Geology comes from the
Greek language: γη, gê, "Earth"
and λόγος, logos, "speech"
So Geology is "talking about Earth"
A nice definition of Geology is:
Geology is a science that deals with the history of the Earth as recorded in rocks
Geological forceshave determined the look of the Texas Hill Country
There was a time when continents were together. When bumping into each other, mountain ranges were pushed up and folded. The area of today's southern United States had a huge mountain range, the Ouachita Mountains. They were pushed up by the African plate pushing against the North American plate. During the Triassic Period about 240 million years ago, the continental plates of North and South America and Africa were together and started drifting apart.
Texas and the southern part of the American plate was pushed up and folded by the African plate, the Ouachita Mountain range was built.
The name Cretaceous period comes from the Latin language for "chalky" and is usually abbreviated K for its German translation Kreide = chalk. At the beginning of the Cretaceous period, about 145 million years ago, the ancestral Gulf lapped upon the edge of the Texas continent.
The Bear Springs Blossom Nature preserve was covered by a warm shallow ocean about 120-125 million years ago.
Much later nearly all of Texas was covered by the sea. Multitudes of sea life deposited their calcium carbonate sediment – the origin of limestone or "lime" shells and skeletons.
The Cow Creek, Glen Rose, and Edwards were derived largely from skeletal calcium carbonate sediment.
The Glen Rose is the oldest of these limestone layers on our Nature preserve. In the subsurface under our preserve lies the Cow Creek limestone. The Glen Rose in Central Texas was deposited from about 113-108 million years ago and consists of layers of yellowish limestone, compacted clay, compacted silt, and soft lime mud. The "soft lime mud" usually is a mixture of lime mud and clay, which is called marl.
You can see the Glen Rose formation in stream valleys and road cuts throughout Bandera County.
The sea that deposited the Glen Rose progressively advanced onto the continent.
After the sea level was driven about to the middle of Texas, pure carbonate sediment was deposited in this area.
This deposition is now called the Edwards Group of formations, which overly the Glen Rose formation. The Edwards was deposited from about 108 to 100 million years ago. Remnants of the Edwards are on the high hills in Bandera County.
You all heard about the Balcone's fault zone.
The Balcones faulting occurred around 20 million years ago.
Balcone's Fault Zones
Graphic by Professor Bill Ward, a member of
Bear Springs Blossom Nature Conservation
Far below the limestone layers, a thick salt layer was deposited by evaporating sea water.
The northwestern margin of the Gulf of Mexico subsiding caused enormous tension and movements far beneath the layer-cake surface. A huge part of Texas surface bulged, and a huge section was sliding on the thick salt layer downward toward the Gulf Basin.
Because of all the movement of this huge weight, the region was lifted up, building the Edwards Plateau.
The "hinge" of that uplift or downwarp runs parallel to Interstate 35 between Austin and San Antonio along what we call the Balcone's Escarpment. The Balcone's Fault Zone forms the eastern edge of the Edwards Plateau and the southern edge from San Antonio nearly to Del Rio.
The increased elevation of the Edwards Plateau area increased the gradient of streams, thereby increasing the ability of the streams to downcut and erode. Since that time natural processes of weathering and erosion have carved the limestone into hills and canyons that you see today in Bandera County. You can also say that the streams cut the canyons and what is left between the canyons are our Texas Hill Country hills.
Stone is hard and water is soft, but water is powerful and persistent and wears away stone. Water penetrates pores and cracks - when it freezes it expands, sometimes breaking the stones. Rainwater picks up carbon dioxide from the air and soil and forms a dilute solution of carbonic acid, which can easily dissolve limestone.
Caverns, sinkholes, and fantastically shaped pieces of limestone result.
See a list of strong earthquakes on Earth
To get more information on Geology, please become a member of our charitable nonprofit-organization!
Your donation is fully tax-deductible. Click on the "Join us" button!
Contact us - learn to understand Nature!
Become an expert, become a BSB Master Conservationist!
As a member of Bear Springs Blossom Nature Conservation. You will get free advice and help! Membership starts at $1 (one) a month.
Think about how wonderful our Earth was created...
Live in Harmony with Nature + Learn to understand Nature!
Fossil seen in limestone wall at a road cut in the southern Texas Hill Country
Earth's surface consists of many continental and oceanic plates moving all the time causing earthquakes
BSB Nature preserve - -
BSB members strongly believe that
Conservation Education CE is the only solution to give the majority of human beings a better life on Earth.|
Copyright Bear Springs Blossom Nature Conservation
International charitable nonprofit organization 501(c)(3)
All rights reserved
Peter Bonenberger - volunteer + president
Marianne Bonenberger + director of education
BSBNCG POB 63295 Pipe Creek 78063 TX USA
Save Earth - BSB email: email@example.com
See graphics of Earth's solar system
Facts on Earth's Atmosphere
Read more about Life on Earth
Importance of the Gulf stream current
Bacteria - uncountable in numbers
Hear and feel the wonders of Earth
BSB tries to be as accurate as possible, but we are not responsible for broken or false links or misinterpretation
+ BSB was founded 2002 +
As a nonprofit organization, BSB is always grateful for donations in support of our mission.
How life works
Earth facts numbers
Earth from space
Water - fantastic stuff
Tips how to save water
About AIR - Air Facts
Cap + trade
No matter what
as a BSB member
you are much
more likely to
be ready for it!
Be more happy!
have more money!
be more attractive!
have a better life!
have a longer life!
BSB Online book
Use our BSB Directory
WHAT did God say?
Why Nature conservation?
BSB members save money
Art in Nature
Why trees are
What's the value of
an old tree?
Make a difference!
Have a better Life!
Have Nature questions?
Zoom in Nature
All about Bandera TX
River + Parks
from all over Earth
|Fair Use Notice|
All material on 1000+ BSB web-pages is intended to advance understanding of the environmental, social, scientific, and economic issues of Nature conservation. We believe this constitutes a "fair use" of any copyrighted material as provided for in section 107 of the U.S. Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit to those who have expressed an interest in receiving the included information for research and educational purposes. If you wish to use copyrighted material from our websites for purposes of your own that go beyond "fair use," you must obtain permission from the copyright owner. If you are the owner of copyrighted material(s) appearing on this site, and wish it to be removed, please contact us directly.