Geologic Points of Interest by Activity - Springs/Falls

On Highway 21 to Lowman, ID, turn left on the Banks-Lowman Road or take Highway 55 north to Banks, turn right on Banks-Lowman Road.

The Kirkham Hot Springs is easily accessible on foot from the Boise National Forest Kirkham Campground. Summer season is usually quite busy and nightly closure from 10:00 p.m. to 6:00 a.m. is strictly enforced. Steamy waterfalls and hot pools make this site very inviting to the weary traveler.

The Kirkham Hot Springs is part of the South Fork Payette Geothermal System (SFPGS). This series of thermal springs is located along faults that fracture the Atlanta lobe of the Idaho batholith. Seismic activity helps to keep the hydrothermal systems in this region active. An earthquake with the magnitude of 7.3, the highest magnitude ever recorded in Idaho, occurred as recently as 1983. Noticeable changes in flow rates of the springs were recorded near the epicenter, which was located just north of the SFPGS.

The Idaho batholith is comprised of Cretaceous period micaceous granites, leucogranites, and gradiorites. Tertiary plutons of granite and diorite are also present (Druschel et al., 2001).

In the mid-1930's the Civilian Conservation Corps ( CCC) constructed a cement container to capture the thermal heated water of Granite Hot Springs. Temperatures vary from 93 degrees F in the summer to 112 degrees in the winter. The 45 by 75 foot hot pool is bordered by large granite boulders and beautiful scenic views. Granite Campground is located about a mile away from the site.

The spring flows from the contact of the Cambrian period Death Canyon Limestone and Flathead Formation. Fluctuating flow indicates influence by surface waters. Seismic activity creates fractures where surface water seeps into the cracks, is transported deep within the earth, heats, and rises again to the surface through other fractures (Breckenridge et al.1978). Regionally, the thermal spring is located in the Gros Ventre Mountains that were thrust upward along the Cache Creek Fault millions of years ago. The peaks are mainly Paleozoic and Mesozoic age sedimentary rocks jaggedly carved through glacial activity (Blackstone, 1988).

Located near the mouth of Hoback Canyon, no interpretive signs mark the location, but the spring’s presence is obvious at a small gravel pullout when compared to the natural river system beside it. Caribbean blue waters seem out of place next the normal green hues of the running water. The spring enters the river just a few feet above the water level from a talus slope opposite the road.

Once again, as described with other various springs on these pages, seismic activity comes into play. Near the spring, Mississippian carbonate rocks are complexly folded and thrust-faulted. The thrusting is associated with the hanging wall of the Shepard thrust (Roberts, 1990). Surface waters seep into the fractures dissolving carbonate rocks along the way and exit the fracture depositing calcium carbonate deposits. This is likely the cause of the apparent milky- blue color in the water. An obvious sulphur smell gives these hot springs their characteristic name.

Situated at the base of limestone cliffs, Periodic Spring discharges about 285 gallons per second. Spring water gushes from an opening for several minutes, stops abruptly, then begins a new cycle a short time later. Intermittent water flows range anywhere from four to 25 minutes and the water is clear and cold. This is a very rare type of spring with only a few known in the world. Unlike thermal geysers, where water is heated and pressurized, this spring has disputed theories as to its perplexing behavior. One theory suggests siphoning action. Water fills a subsurface reservoir and flows freely from the opening until the water level drops below the siphon intake. The reservoir then refills and the process starts all over (Corliss, 1990; Mohlenbrock, 1990).

Multiple waterfalls over spring-deposited tufa make this creek an interesting visit. The creek follows tufa terraces and falls for two miles. The cold springs are located in the Triassic Dinwoody Formation, but the source of the water is probably the Madison Limestone to the east. The area is associated with the Cabin Creek overthrust, part of the imbricate thrusting seen in this area of Wyoming.  (Breckenridge et al. 1978).

Tufa is found mainly in areas where resurgences of ground water have traversed limestone formations. The tufa is spongy or cellular in character and encloses fragments of rocks and plants. It also cements the bottom of the streambed into a material known as calcrete. The build up of tufa encrusted moss, algae and other debris create barriers to stream flow and produce water falls and cascades. The water in the stream has a distinct sulfer smell. Sulfer is a common element in sedimentary rocks and dissolves readily into ground water.

Big Springs is the source of the South Fork of the Henrys Fork River. Designated as a National Natural Landmark in 1980, the springs are the only first-magnitude spring ( discharges water at a rate of at least 100 cubic feet per second) in the country that emanate from rhyolitic lava flows of the Madison Plateau.

During your visit, note the large brown trout that greedily feed on tourist handouts. Fishing is not allowed near the springs.

The largest instantaneous discharge observed at any spring in Utah was 314 cubic feet per second at Mammoth Spring. The source of the water is believed to be precipitation on the Markagunt Plateau that recharges the karst forming limestone units within the Claron formation and overlying volcanic lava flows. (From: Mundorff, 1971)

Three interlinked loop paths criss-cross the pools and streams, in places on raised boardwalks above the ponds with their clear water, travertine (tufa) terraces and a variety of lush plant life. The ponds have abundant fish, and otters may also be seen occasionally. Further up the slopes the path follows the gushing whitewater streams that feed the lower pools to a ground water discharge area that provides the main source. Here, the water (on average 7 million gallons per day) seeps up through a thin part of the layer of glacial debris that fills the valley.

Historically, Rick's Spring was used as a mountain spring water source until visitors became ill after drinking from it. Ice jams on the Logan River in 1972 and dye traces led scientists to find that the water of Rick's Spring was actually coming directly from the Logan River through a fracture in the rock. Folded rocks gave way to fractures and it is evident one of these fractures allows the river water to seep through the rock and exit at Ricks Spring. Great interpretive signs point out the folding and fracturing as well as denote who the spring was named after.