A cache by FishyFinnegan Message this owner

Hidden : 8/14/2023

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Size: Size: other (other)

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Geocache Description:

Possom Kingdom Arch Bridge.
At 433 feet long, it is the longest stone arch bridge in Texas. Construction materials were quarried from local limestone, and the bridge features fine craftsmanship, the result of an investment in infrastructure after the Great Depression in 1942.

The bridge materials and the use of the spot by the United States Geological Survey provide excellent insights as an Earth cache.

The United States Geological Survey, founded as the Geological Survey, is an agency of the United States government whose work spans the disciplines of biology, geography, geology, and hydrology.

We all drive past bridges every day and often don’t stop to consider the incredible impact they have on multiple aspect of a location from agriculture, to water preservation, flood management and others.

The way that water interacts with the natural lay of the surrounding terrain and manmade aspects of the area are measured. And bridges are designed to assist in that process often having gauges on or around them due to their importance.

Gauges provide practical data

Here are some possible ways our gauge data serves the public:

A landowner might use river height (also known as gage height) to determine if there is an imminent risk of flooding to their property
A property buyer or developer might use flood models based on historical data to determine the risk of flooding over a given time period
A dam operator can determine the timing and amount of water to release based on the conditions upstream and downstream
A scientist can study big picture trends of our waterways
Water managers can more efficiently distribute water during times of drought

So the use of the geological tools such as gauges is important to compare today, yesterday and the future of an area.

The USGS operates over 11,000 gages, making it one of the largest networks in the world. Streamgages can be found in all sorts of locations: forests, mountains, prairies, coasts, downtown cities, and more.

Behind every gauge is a dedicated team

Every gage requires servicing to ensure it reports accurate data. Hydrologic technicians will service gages on a fixed schedule and as issues arise. On-site, technicians will take velocity measurements which are used in our calculations. They may also clean sensors to prevent them from fouling, as sediment buildup, leaves, and even beavers have been known to interfere with accurate reporting.

Learn more about the USGS streamgage network.

Texas Limestone

By the early Cretaceous (approximately 140 million years ago), the shallow Mesozoic seas covered a large part of Texas, eventually extending west to the Trans-Pecos area and north almost to present-day state boundaries. Today, the limestone deposited in those seas is exposed in the walls of the magnificent canyons of the Rio Grande in the Big Bend National Park area and in the canyons and headwaters of streams that drain the Edwards Plateau, as well as in Central Texas from San Antonio to Dallas.

The bridge at this location is made from the limestone that forms many of the large bluffs and cuestas in the Palo Pinto country. The Brazos River was dammed by Morris Shepherd Dam to form Possum Kingdom Lake; magnificent high cliffs of Winchell Limestone are exposed there. (Take Red Bluff Drive west from Texas 16 past the Fish Hatchery to a small picnic area and gate.) The limestones are dominantly mudstones with phylloid algae, but grainstones with echinoderm fragments form bars, channels, and dunes, indicating higher wave or current energy.

Despite the imposing appearance of this carbonate unit, it changes character entirely within ten miles northeast in outcrop or northwest in the subsurface; it becomes mostly a sandstone-shale sequence related to a delta system near Jacksboro. Muds put out by rivers feeding the delta may help to close carbonate deposition; the algae and other carbonate-secreting organisms need clear waters.

To view the Winchell close-up, there are roadcuts on Texas 16 to the north and south; however, pullouts are few, so please be careful!

Possum Kingdom Stone Arch Bridge was built by the workers assigned to the Work Projects Administration (WPA) from 1940 to 1942 as part of President Franklin D. Roosevelt’s Second New Deal. After the Great Depression, millions were unemployed and the WPA brought together workers from all walks of life. Coal miners were brought in to build the bridge, bringing with them the skill set that was needed for such a task. It was their skill of handling and cutting stone that made the difference in the project. There were approximately 74 skilled workers and 250 unskilled workers or laborers on the two-year project.

The spans of the bridge range between 23-35 feet. State highway engineers chose the heavy masonry form to withstand flood waters from the Morris Sheppard Dam located just upstream.
So why use Limestone?
#1. Limestone Is a Great Material for Tiles

Limestone forms when sediments compress over time, making it a rugged surface that’s just perfect underfoot or tire. Limestone pavers and tiles can be used for any floor or walkway surface whether it be a bathroom, a patio, or around the pool. And it holds up well outdoors in different temperature zones.

#2. Cladding Panels Can Be Made from Limestone

Architects love to use limestone for buildings, including siding. Limestone panels give any structure a classy look and they offer great protection against the elements, especially in warm-weather regions.

#3. Limestone Is Extremely Durable

One of the many limestone benefits is its strength and durability. It is among the most resilient of all-natural stones thanks to its density. Though it is softer than marble and granite, it wears well over time, making it a good option even in high-traffic areas.

People have been using limestone as a building material for centuries, largely because of how long it lasts. Because it’s stone, it’s particularly weather-resistant and erosion doesn’t weaken its structural integrity. Many contractors recommend using a sealant on the surface, which makes it hold up well against stains and dirt, too.

#4. Limestone Is a Universal Building Stone

Architects and builders also use limestone in construction because of its versatility. The stone is durable enough to be underfoot, making great pavers, but can also be used in tiling, paneling, coping stones, and a myriad of other applications. Limestone’s pale hues complement just about any color scheme and it can look both luxurious and rural chic.

Limestone is easily worked, as well. It can be made into dense blocks, medium-sized bricks, and thin tiles. Sculptors have used it for centuries because it’s easy to cut, carve, and make designs in. It also uses less energy to produce than other building materials.
Famous Limestone Buildings Around the Globe

Some of the world’s best-known and most-beloved structures were constructed from limestone. It was commonly used as an alternative to marble and granite in municipal buildings, bridges, colleges, and churches. The stone’s hardy nature has allowed many of these buildings to last for centuries.

Notable buildings made of limestone include:

The Great Sphinx
The Great Pyramid
The Parthenon
The Roman Colosseum
The Empire State Building
The Arc de Triomphe in Paris
The Lincoln Memorial
The Washington National Cathedral
The Pentagon
United States Holocaust Memorial
The Biltmore Estate
Chicago Art Museum
Courthouses and Capitol buildings across the country

Congrats to TexasGreg for the FTF!

To log this earth cache, message or email us and copy and paste these questions, along with your answers. Please do not post the answers in your log, even if encrypted. There's no need to wait for confirmation from us before you log, but we will email you back if you include your email address in the message. Group answers are fine; just let us know who was with you.

1. The name of this earth cache: Possum Kingdom Stone Arch Bridge ABEC #3

2. Observe: Describe color of the materials used on the bridge today. What, if any, evidence do you see of erosion from the water or other elements?
3: Opinion, Based on your answer above and the lesson content. Was the use of limestone a good choice?

4. What factors do you think contributed to the builders using limestone to construct the bridge? Why?

5. Observe: At the location of the Earth cache you can see a marker at your feet.

What is the United States Geological Survey doing at this location as indicated on the US Geological Survey marker?
Why is this important at this spot?
6. Send a photo of the US GS marker (only in the answer section) You can elect to be in the photo or not. THIS IS A REQUIRED PHOTO ONLY FOR ANSWERS SUBMITTED