GC39KHJ Thousand Springs (Earthcache) in Idaho, United States created by BoCoFisher

GC39KHJ ▼

A cache by BoCoFisher Message this owner

Hidden : 3/18/2013

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Size: Size: other (other)

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Thousand Springs

Some of the most spectacular springs in the world are found in the Thousand Springs area along the Snake River Canyon in Southern Idaho. Thousand Springs is the name given to the many outlets flowing from the Snake River Plain Aquifer into the Snake River. The aquifer extends from near the western boundary of Yellowstone National Park in eastern Idaho to the Idaho-Oregon border where the Snake River enters Hells Canyon. The US Geological Survey has identified 19 major springs, in an area called Thousand Springs, that discharge to the Snake River starting with Devils Washbowl (near Kimberly, about 10 miles east of Twin Falls) on the east and ending with Birch Creek (about 3 miles west of Hagerman) on the west. Eleven of the 65 springs in the United States with a discharge greater than 100 cubic feet per second are found along this reach of the Snake River.

Throughout history lava flowed time and time again onto the eastern Snake River plains more than 100 miles northeast of here. The lava eventually covered the old river channels of the Lost River and the Little Lost River and slowly changed the course of the Snake River. No longer able to reach the Snake River on the surface, the waters from these rivers went underground. The rivers actually disappear into the ground, hence the name Lost River and Little Lost River.

The underground layer of water-bearing permeable rock which forms in the eastern part of the Snake River Valley is known as the Snake River Aquifer. The aquifer is as much as 5,000 feet deep, although water travels most rapidly in the area 300–500 feet below the surface of the ground. Total ground-water storage in the upper 500 feet of the aquifer is estimated at 200 to 300 million acre-feet, roughly the equivalent of Lake Erie. Because of the massive amount of water in this aquifer it is estimated that the water going underground into the aquifer takes nearly 200 years to travel the 100+ mile distance before it bursts forth from the springs. The spring water temperature is a constant 58 degrees Fahrenheit year around. The aquifer drains to the Snake River and flows mainly southwest. There are two main areas of natural discharge: Springs along the Snake River near American Falls Reservoir with discharges of about 2,600 cubic feet per second, and here at Thousand Springs in this area west of Twin Falls where the collective discharge is about 5,200 feet per second.

Water flowing from the canyon walls has traveled under the lava plains through the porous volcanic rock. The springs emerge from the sides of the canyon walls through pathways between the basalt layers composed mainly of sand, silt, and clay. Permeable basalt zones are mainly the tops and bottoms of lava flows. The layer of rhyolite found under the basalt does not have high permeability because many of the pore spaces are filled with chemical precipitates. This highly dense layer of rhyolite does not allow the water to flow into the lowest part of the river canyon but rather forces the water to emerge from the walls of the canyon cliffs. These emerging waters are known as Thousand Springs.

From where you stand on the roadside of Highway 30 you can see numerous springs flowing from the sides of the canyon walls. Enjoy the fascinating sights!

Resources:
1) Idaho Highway Historical Sign
2) Data Report: Spring Discharge along the Milner to King Hill Reach of the Snake River. IDAHO WATER RESOURCES RESEARCH INSTITUTE UNIVERSITY OF IDAHO, IDAHO FALLS May, 2002
3) Digital Geology of Idaho-Snake River Aquifer
4) Idaho Department of Parks and Recreation

Logging Requirements:
Email to me the answers to these 3 questions. Reference GC39KHJ and the title "Thousand Springs" on the first line. Photos are welcome; do not show answers to questions in photos or on photo captions. To log your find you must physically visit the site and answer the following questions:

1) As you observe the springs on the walls of the river canyon you can see that some springs produce large amounts of water springing forth and others are small outlets for the water. Share why do you think that happens?
2) The walls of the river canyon are made of rocks. From your observations describe the size and nature of the rocks on the wall.
3) It seems quite possible that water could emerge in locations that feed into a lake bed. From looking at the picture above titled "Simplified Geologic Cross Section of the eastern Snake River Plain" you can see that Mud lake is an example of a lake fed from this aquifer. Why do you believe that a lake has not been formed in this area near the Snake River in this manner?
----------------------------- Congratulations to a mighty fine group of geocachers for Co-FTF honors: tentha, Johnny Ringo, X$r, RW, D$r and Dan Zilla.

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Thousand Springs EarthCache

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