Canyon Lake Gorge
Encyclopedia
Canyon Lake Gorge is a gorge
around 1 miles (1.6 km) long, hundreds of yards (metres) wide, and up to 50 feet (15.2 m) or more deep, which was carved through limestone
in 2002 when extensive flooding of the Guadalupe River
led to a huge amount of water going over the spillway from the Canyon Lake, Texas
, reservoir. The gorge provides a valuable exposure of rock strata
as old as 100 million years showing fossils and a set of dinosaur tracks, and forms a new ecosystem
for wildlife with carp
and other creatures in a series of pools fed by springs and waterfalls.
The Gorge Preservation Society formed as a local citizen's group is developing long-term plans for the Gorge in partnership with the Guadalupe-Blanco River Authority
and the U.S. Army Corps of Engineers. Public access to the gorge is restricted to guided tours along a designated route for a demanding hike lasting about three hours. Availability of tours is limited, no pets are allowed and no rock or fossil collecting is allowed. Research permits can be obtained by university or scientific research groups.
for approximately six weeks, the first time the spillway had been in use since the reservoir dam was constructed in 1964. Normally, the flow out of the reservoir is around 350 cubic feet (9.9 m³) of water per second. The Guadalupe River
basin forms a part of "Flash Flood Alley" which is one of the river basins most prone to flash flood
ing in the world. Nine people were killed by the flood event over a 20 miles (32.2 km) stretch of the river, which damaged or destroyed 48,000 homes and cost around $1 billion in damages, but the Canyon Lake manager has stated that even though the floodwaters went over the spillway, the dam still prevented an estimated $38.6 million in damages downstream during the event.
and the U.S. Army Corps of Engineers signed an agreement to develop the gorge as an educational and natural resource.
In their 2010 study, Michael Lamb of the California Institute of Technology and Mark Fonstad of Texas State University documented the dramatic transformation of a section of the Guadalupe River Valley landscape into a steep-walled bedrock canyon in just three days. The scientists documented the excavation of bedrock limestone to an average depth of over 20 feet and average width of 130-200 feet for a distance of over one mile. The “plucking” and transport of massive boulders from the site resulted in the formation of several waterfalls, inner channels, and bedrock terraces. The abrasion of rock by sediment-loaded water sculpted walls and created plunge pools and teardrop-shaped “streamlined islands”. Although some of the geological formations present in the gorge are known to be associated with rapidly flowing flood water (such as the streamlined islands), other formations (such as the inner channels, knickpoints and terraces) have traditionally been interpreted through the “long ago and very slow” paradigm of geologic time in response to shifting climate or tectonic forcing.
Typically a steep-walled, narrow gorge is inferred to represent slow persistent erosion. But because many of the geological formations of Canyon Lake Gorge are virtually indistinguishable from other formations which have been attributed to long term (slower) processes, the data collected from Canyon Lake Gorge lends further credence to the hypothesis that some of the most spectacular canyons on Earth may have been carved rapidly during ancient megaflood events. Additionally, because the flood conditions under which the gorge was formed are known, Canyon Lake Gorge provides a means of developing improved computer model reconstructions of pre-historic floods to determine water volume, flood duration and erosion rates.
Canyon
A canyon or gorge is a deep ravine between cliffs often carved from the landscape by a river. Rivers have a natural tendency to reach a baseline elevation, which is the same elevation as the body of water it will eventually drain into. This forms a canyon. Most canyons were formed by a process of...
around 1 miles (1.6 km) long, hundreds of yards (metres) wide, and up to 50 feet (15.2 m) or more deep, which was carved through limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
in 2002 when extensive flooding of the Guadalupe River
Guadalupe River (Texas)
The Guadalupe River runs from Kerr County, Texas to San Antonio Bay on the Gulf of Mexico. The river is a popular destination for rafters and canoers. Larger cities along the river include New Braunfels, Kerrville, Seguin, Gonzales, Cuero, and Victoria...
led to a huge amount of water going over the spillway from the Canyon Lake, Texas
Canyon Lake (Texas)
Canyon Lake is a reservoir on the Guadalupe River in the Texas Hill Country in the United States. Canyon Lake is a U.S. Army Corps of Engineers reservoir formed on the Guadalupe River in Comal County by Canyon Dam, which is located about sixteen miles northwest of New Braunfels. The dam, lake,...
, reservoir. The gorge provides a valuable exposure of rock strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
as old as 100 million years showing fossils and a set of dinosaur tracks, and forms a new ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
for wildlife with carp
Carp
Carp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain...
and other creatures in a series of pools fed by springs and waterfalls.
The Gorge Preservation Society formed as a local citizen's group is developing long-term plans for the Gorge in partnership with the Guadalupe-Blanco River Authority
Guadalupe-Blanco River Authority
The Guadalupe-Blanco River Authority or GBRA was formed in 1933 by the Texas legislature. Its main concerns are water supply and water conservation in the Guadalupe River Basin, which includes the Blanco, Comal, and San Marcos rivers. The authority extends over ten counties...
and the U.S. Army Corps of Engineers. Public access to the gorge is restricted to guided tours along a designated route for a demanding hike lasting about three hours. Availability of tours is limited, no pets are allowed and no rock or fossil collecting is allowed. Research permits can be obtained by university or scientific research groups.
The flood event of 2002
In July 2002 up to 67000 cubic feet (1,897.2 m³) of water per second flowed over the spillway of Canyon Lake, TexasCanyon Lake (Texas)
Canyon Lake is a reservoir on the Guadalupe River in the Texas Hill Country in the United States. Canyon Lake is a U.S. Army Corps of Engineers reservoir formed on the Guadalupe River in Comal County by Canyon Dam, which is located about sixteen miles northwest of New Braunfels. The dam, lake,...
for approximately six weeks, the first time the spillway had been in use since the reservoir dam was constructed in 1964. Normally, the flow out of the reservoir is around 350 cubic feet (9.9 m³) of water per second. The Guadalupe River
Guadalupe River (Texas)
The Guadalupe River runs from Kerr County, Texas to San Antonio Bay on the Gulf of Mexico. The river is a popular destination for rafters and canoers. Larger cities along the river include New Braunfels, Kerrville, Seguin, Gonzales, Cuero, and Victoria...
basin forms a part of "Flash Flood Alley" which is one of the river basins most prone to flash flood
Flash flood
A flash flood is a rapid flooding of geomorphic low-lying areas—washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or meltwater from ice or snow flowing over ice sheets or snowfields...
ing in the world. Nine people were killed by the flood event over a 20 miles (32.2 km) stretch of the river, which damaged or destroyed 48,000 homes and cost around $1 billion in damages, but the Canyon Lake manager has stated that even though the floodwaters went over the spillway, the dam still prevented an estimated $38.6 million in damages downstream during the event.
Educational and natural resource
On November 29, 2005, a ceremony was held in which representatives of the Guadalupe-Blanco River AuthorityGuadalupe-Blanco River Authority
The Guadalupe-Blanco River Authority or GBRA was formed in 1933 by the Texas legislature. Its main concerns are water supply and water conservation in the Guadalupe River Basin, which includes the Blanco, Comal, and San Marcos rivers. The authority extends over ten counties...
and the U.S. Army Corps of Engineers signed an agreement to develop the gorge as an educational and natural resource.
Significance for Geologists
The 2002 flood event at Canyon Lake and subsequent rapid formation of Canyon Lake Gorge presented a unique opportunity to study the incredible geomorphological power of rapidly moving water and to better understand the process of canyon formation.In their 2010 study, Michael Lamb of the California Institute of Technology and Mark Fonstad of Texas State University documented the dramatic transformation of a section of the Guadalupe River Valley landscape into a steep-walled bedrock canyon in just three days. The scientists documented the excavation of bedrock limestone to an average depth of over 20 feet and average width of 130-200 feet for a distance of over one mile. The “plucking” and transport of massive boulders from the site resulted in the formation of several waterfalls, inner channels, and bedrock terraces. The abrasion of rock by sediment-loaded water sculpted walls and created plunge pools and teardrop-shaped “streamlined islands”. Although some of the geological formations present in the gorge are known to be associated with rapidly flowing flood water (such as the streamlined islands), other formations (such as the inner channels, knickpoints and terraces) have traditionally been interpreted through the “long ago and very slow” paradigm of geologic time in response to shifting climate or tectonic forcing.
Typically a steep-walled, narrow gorge is inferred to represent slow persistent erosion. But because many of the geological formations of Canyon Lake Gorge are virtually indistinguishable from other formations which have been attributed to long term (slower) processes, the data collected from Canyon Lake Gorge lends further credence to the hypothesis that some of the most spectacular canyons on Earth may have been carved rapidly during ancient megaflood events. Additionally, because the flood conditions under which the gorge was formed are known, Canyon Lake Gorge provides a means of developing improved computer model reconstructions of pre-historic floods to determine water volume, flood duration and erosion rates.