Final Blog
The Balcones Fault Zone runs through the south central part of Texas. Running directly through Austin, most of this area is considered to be subtropical humid to sub-humid. The landscape was created somewhere between 27 million and 12 million years ago by tectonic processes, including the extension of the continental crust, causing the many faults in the area. It is a grouping of many normal fault along a fairly large area.

1000 years from now
Since there is little to no seismic activity in the area anymore, I think the Balcones Fault Zone will become shaped by the weathering, erosion and deposition of new sediment. As we have seen this year, the area has become susceptible to long droughts, decreasing the growth of vegetation, and making it more prone to weathering and erosion. As these processes continue, the escarpment will be begin to change.

Actually, it is possible the only reason the escarpment in the Balcones Fault Zone is still so prominent is due to the differential erosion of the rocks.The more resilient rocks resist the weathering processes.

10,000 years from now
The composition of the rocks, mostly limestone, lend themselves to physical and chemical weathering, and erosion. But the different types of limestone are susceptible to different degrees. As differential erosion occurs, the side that once appeared to be up thrown might be eroded to become even with the lower side. Each layer of rock has a different ability to withstand weathering processes. While on side begins to erode faster than the other, a new layer of rock is exposed and might be of a"harder" composition. The steep cliffs of the fault also increase the ability of water to weather and erode the rocks. Slowly, the fault will be weathered and eroded away, and the escarpment will no longer be as obvious as it was once.

Possible changes in the fault

1,000,000 years from now
Eventually, the surface representation of the Balcones Fault will disappear. The escarpment will no longer be distinguishable from the surrounding landscape. It might also be important to point out that many of the faults have become parts of rivers or lakes. As the water weathers and erodes the susceptible limestone, chances of mass wasting from undercutting increase and more quickly change the landscape.

In conclusion
The Balcones Fault Zone was created in an instant (in geologic time). As the landscape of this area is left to the processes of erosion and weathering, the evidence of this massive seismic event will slowly fade away. Perhaps, in the future, another tectonic process will once again reshape the landscape of this area. When the escarpment and rolling hills caused by the Balcones Fault Zone are merely historical data in a geology book (if life on Earth still exists), there maybe another event that becomes part of geographical research.

Sources
 http://www.lib.utexas.edu/geo/ggtc/ch3.html
 http://www.utexas.edu/depts/grg/kimmel/GRG301K/grg301kkoppen.html
 http://www.tshaonline.org
 http://water.usgs.gov/ogw/karst/aquifers/edwards/index

Blog #3

Let's talk about the weather! The Balcones Fault area of Texas is considered to have a humid subtropical climate (Cfa according to Koppen). The summers are hot and humid with the warm air coming from the Gulf of Mexico, and mild, fairly dry winters. Recently, the record high in Austin was 112 degrees Fahrenheit. Movement of the Polar and Pacific Jet streams encouraged the dry, warm weather putting this area and most of the Midwest in a drought.





Though this area of Texas is prone to drought, heavy rains are not uncommon. Large storm systems, as well as hurricanes, move through the Gulf of Mexico towards these areas. While no longer hurricanes when they reach Austin, the storm systems begin slowing over the land and dump rain on the region.

Flood in central Austin along Shoal Creek

 As warm air from the Gulf of Mexico comes in contact with the escarpment, it rises and can produce rainstorms due to the orographic cooling. The area is also located where the polar air mass and the easterlies converge, sometimes resulting in heavy rains. The rolling hills and steep slopes, along with thinly soil covered limestone bedrock, increase the rate of run-off. The Balcaones Escarpment between Austin and San Antonio is one of the three areas most susceptible to flash floods in the nation. 

Onion Creek flooding in 2010

Sources
http://www.tshaonline.org
http://en.wikipedia.org/wiki/Austin,_Texas#Geography
http://impactnews.com/articles/the-memorial-day-flood-of-1981
http://www.lib.utexas.edu/geo/balcones_escarpment/pages1-14.html

Post #2

During the Paleozoic era , the Balcones Fault Zone was part of the ancient Ouachita rock structure. The area was covered by a sea that began to recede during the Pennsylvanian period, only to be covered again during the Cretaceous period when most of the parent sediment was deposited. The shale, limestone, and sandstone of the fault area reflect the various changes in the sea level.

The major movement along the fault occured between 27 and 12 million years ago, when the east sideof the fault was downthrown and the west upthrown. These faults created what is now known as the Texas Hill Country, with many grabens and horsts making the rolling landscape.

Taken from the top of another horst.

The Edwards Aquifer is also a result of the fault. The exposed more permeable limestone surrounded by the less permeable rock allows for fresh water to be held in the aquifer. The joints and fissures in the rock help the surface water travel down into the aquifer.

Me and my dad in front of escarpment

 The dissolving action of this ground water also creates sink holes and caves. The limestone solution creates caverns filled deposited limestone structures called karst.

Karst in cavern in Southwest Texas

A large sink hole above the aquifer

A sinkhole near Barton Springs

The composition of the rocks as well as human involvement like road cuts, lead to many different weathering processes, and to other weathered landforms.

 The vegetation seen at this road cut also aids in the weathering process through root wedging. The rocks show different rates of weathering as well, resulting in mass wasting by rock fall and the collection of talus at the base as well as cliff tops and ledges.


http://www.tpwmagazine.com/archive/2009/june/ed_2/index.phtml
http://water.usgs.gov/ogw/karst/aquifers/edwards/index

Blog post #1

The Balcones Fault Zone is an area encompassing a large part of Texas and is actually a group of faults. Created by the extension of the Continental crust, this area shows evidence of mostly normal faults.  The Balcones escarpment, moving west through Austin, is a prominent feature of the landscape. The fault scarp line separates the Edwards plateau to the west from the Gulf Coastal Plain to the east. The hanging wall extends as high as 300 feet in Austin, and shows a throw of nearly 600 at Mount Bonnell.


Mount Bonnell, on the Colorado River in Austin, is located in the fault zone and is a popular tourist attraction.

This formation in San Antonio is a great example of a fault scarp in one many normal faults in the Balcones Fault zone.

There are many representations of the fault around the Austin area, including faults, fractures, caves, sink holes and aquifers. I'll will be in Austin this weekend, and hope to bring back my own photos and information for my next blog!

Sources:

"URBAN GEOPHYSICS: A MAPPING OF MOUNT BONNELL FAULT AND ITS 
KARSTIC FEATURES IN AUSTIN, TX". Mustafa Saribudak, Environmental Geophysics Associates, Austin, TX
"BALCONES ESCARPMENT," Handbook of Texas Online(http://www.tshaonline.org/handbook/online/articles/rxb01), accessed September 20, 2012. Published by the Texas State Historical Association.
http://en.wikipedia.org/wiki/Mount_Bonnell
http://archives.datapages.com
http://www.edwardsaquifer.net/charts.html

Introduction

This blog has been created for Geography 1202 by Allison Huber.

Hi! My name is Allison Huber. I'm a student at the University of Colorado at Denver. This blog will be examining the area known as the Balcones Fault Zone that runs through Texas from the southwest towards the northeast.

I have decided to explore this area to gather a better understanding and appriciation for the many geogrphical characteristics in this area. My family, including my geologist sister, now live in Austin, so I hope to make a field trip here before the semester is over. I have enjoyed the many natural attractions of the Texas Hill Country, and, through this blog, I hope to gain a better apprieciation of this area.
















Images
http://voicesofthetexashills.org/vthgeology_files/image002.jpg
http://www.texasbeyondhistory.net/plateaus/images/UV88-C1911-sm.jpg