The guided tour of Boundary Dam...

on the Pend Oreille River at the US-Canadian border, a concrete arch-gravity dam constructed in 1967 for hydroelectric generation, was nothing short of excellent. A big thank you goes to the engineers from Seattle City Light that owns and operates the structure for a terrific exploration of the facility.

View due north, down river and into Canada from the top of the arch dam, 338 feet (103 m) above the water surface.

View of Boundary Dam from river level, with the six transformer stations on the right where high voltage power lines exit the underground powerhouse.

Service tunnel entrance to the subterranean powerhouse, including the generator hall, transformer stations, the control room for operation of the structure and administrative offices.

Generator Hall, an enormous chamber excavated out of limestone bedrock, showing six turbines with one undergoing refurbishment.

An enormous diluvial dumping...

from pluvial Lake Bonneville occurred through this gap in southeastern Idaho known as Red Rock Pass. The volume of the great gush is estimated at five thousand cubic kilometers (1,200 cubic miles!) of water, released about 14,000 years ago in a catastrophic megaflood that likely lasted weeks to months and scoured the Snake River Plain in Idaho downstream from this site.

Red Rock Pass, a few miles south of Downey, Idaho on US 91. View is to the south, or upstream during the big spill. The vast expanse of Lake Bonneville would have existed on the far side of the skyline ridge, reaching across a third of Utah. Once the rising lake water began spilling across this low point along its shoreline and into the adjacent valley, a great unraveling was unleashed. The unconsolidated surficial alluvium and the underlying sedimentary rocks forming the bedrock sill rapidly eroded, much as a dam collapses when overtopped.

Red X marks the spot (near lower right) of Red Rock Pass, the spillover point for Lake Bonneville. The torrent of floodwater exiting the basin through the gap lowered the overall lake level approximately 105 m (350 feet). Map from Idaho State University.

More here about this tremendous flood from the Idaho State University: Lake Bonneville flood.

Happy 250 America...

as Castle Valley celebrates the semiquincentennial anniversary of the founding of our great nation on this Independence Day. Community tradition has the volunteer members of the Castle Valley Fire Department hosting a breakfast and parade, seen here featuring Engine 37 leading the way.

Cherry on top: Air quality this morning is the best since the summer solstice.

Read the Declaration of Independence.

The lower Dolores River canyon...

a few miles above its confluence with the Colorado River, as seen from Gold Mine Road on an early morning drive.

Note the disturbance on the lower slopes across the river, left of center, the site of a historic placer gold mining operation.

The south side of the La Sal Mountains...

is a well kept secret.

The downtown business hub of Paradox, Colorado on a weekday afternoon.

Buckeye Recreation Area at 7,700 feet (2,350 m) in elevation. It’s a nicely clean and quiet US Forest Service campground.

View of the high La Sals at dusk. No astrophotography was attempted as it is a full Moon.

View to southeast at dawn, looking down the long axis of the Paradox Valley. Early explorers were puzzled as to why the Dolores River flows across this valley rather than along its length, finding it paradoxical. Hence the name Paradox Valley was adopted, and the Middle Pennsylvanian age strata responsible for developing these long and linear collapsed salt-cored anticlines is called the Paradox Formation.

A sandstone-hosted copper deposit...

is found deep in La Sal Creek Canyon where a disseminated ore body formed adjacent to a small normal fault. Following discovery in 1897, the Cashin Mine operated here from 1899 to sometime in the 1950s producing both copper and silver.

Copper mineral staining is common on exposures of the Wingate Sandstone (Lower Jurassic (201.4 Ma - 174.7 Ma)) around the mine site.

Copper mineral staining along a normal fault with a mine adit located on the geologic structure.

Uravan, Colorado may be gone...

but its important nuclear legacy will never be forgotten, having served as the hub of the most productive uranium mining district in the nation. The former company townsite has been erased from most maps following complete environmental remediation of the valley.

Wide panorama from the Star 13 mine portal showing the San Miguel River canyon where the former town and uranium mill was located. Recent remediation efforts resulted in the dismantling of buildings and excavation of radioactive waste and the debris is now sequestered in several containment cells south of the former town site.

The mill and town of Uravan, circa 1970. (Rimrocker Historical Society, donated by Wyatt family.)

Link to NRC closure document: Umetco Uravan.

One of several containment cells in Hieroglyphic Canyon. I measured only background levels of radiation while standing at the fence along the road and snapping this image.

The "hanging flume" is a marvel of engineering...

in the San Miguel and Dolores River canyons, built between 1888 and 1891 by very determined miners working a gold placer deposit further up the canyon. Imagine trying to build this incredible project today!

Remains of the five mile-long wooden flume above the San Miguel River, still clinging to the sandstone cliff after more than 130 years.

Closer view of a section of the wooden flume as seen from an overlook from above, on Colorado 141 north of the former townsite of Uravan.

View from below at a partially restored section of the historic flume. The flume only operated several years after its completion, following which the wooden beams and planks were scavenged and re-purposed for other uses.

Around the nose of a meander bend, the hanging flume hugs the escarpment above the San Miguel River, a short distance above its confluence with the Dolores River.

A portal into an atomic future...

at the Mi Vida Mine, the most significant uranium mine in the largest uranium district in Utah. Located south of Moab on the southwest flank of the Lisbon Valley salt-cored anticline, the mineralized zone is contained in the Moss Back Member of the Chinle Formation (Upper Triassic (237 Ma - 201.4 Ma)). Discovered by Charlie Steen and worked from 1952 to 1960, the high grade uraninite ore was transported to the Atlas Mill in Moab for processing. This is what remains at the historic site today.

Mine entrance at the oxidation/reduction boundary in a mudstone in the Chinle Formation.

Wide view of Mi Vida Mine site. Wingate Sandstone forms the jointed escarpment. The red oxidized zone in the Chinle Formation is clearly seen, with the mine entrance (right of center) in the bleached reduced zone.

Tipple to transfer ore from the ore cars onto trucks for transport to the mill for processing.

Electric tender and ore cars, frozen in space and time.

Comprehensive overview: Uranium and Vanadium Resources of Utah (pdf).

Viewing pictographs under different wavelengths...

of light reveals hidden details not seen by the naked eye when observing rock art under the visible part of the spectrum. Here are three pairs of comparative images of several sections of the wonderful pictograph panel in Buckhorn Wash in the San Rafael Swell, a small portion of which is seen below.

The following pairs of images first show an unretouched raw image followed by an enhancement filter applied by DStretch software.

The software is available at DStretch.com.

An interesting discovery along Castle Creek...

by an archeological survey crew, excitedly shared with me yesterday, only a short distance off a singletrack that I frequently ride. Cool beans.

Boulder mortar or bedrock metate on a sandstone slab.

Note the fine detail on inner surface showing linear striations consistent with wear marks created by a back-and-forth grinding motion.

Breaking in the brand new Bronco...

on the Dome Plateau today. Please excuse the Bronco porn that follows but this is its first time off road since being assembled only 28 days ago in Michigan.

Expansive view towards the south from a high point along the trail.

So-called “Cave Spring” in the Entrada Sandstone escarpment, used historically by ranchers to provide water to stock.

Relict uranium miner’s cabin on Owl Draw Upland.

The new manual Ford Bronco Badlands/Sasquatch is an enormously capable machine that will open up more areas in the backcountry for exploration. What’s a retired geologist to do when not mountain biking or launching rockets?!

The mighty tamarisk leaf-eating beetle...

caught in the act of defoliating a tamarisk on my property in Castle Valley. Large swaths of the invasive tamarisk along the Colorado River are being stressed this year, likely due to the widespread emergence of the tiny beetle following a very mild winter. If one listens closely you can hear them munching away. Go, beetle, go!

Tamarisk leaf-eating beetle (Diorhabda elongata), approximately 5 mm long.

Let’s get small: Macro image of a molting beetle. Look closely.

This beetle was introduced at Potash and at Dewey Bridge in 2004 as an experiment in biocontrol but it never fully eradicated the tamarisk along the riparian corridor, though this year they are very heavily stressed, likely aided by the hot and dry weather this spring and early summer.

Stressed tamarisk on both sides of the Colorado River upstream of Big Bend.

Colorado River upstream of Take Out Boat Ramp showing highly stressed tamarisk on both banks, yet the voracious beetle has left the gambel oaks, cottonwoods, willows and sandstone (!) untouched.

Counting every drop...

of legally diverted water from Castle Creek, now being performed digitally and remotely since the Utah Department of Natural Resources has just installed a real-time monitoring point using a solar powered sonic water level sensor and radio transmitter. Previously, someone would have to visit this site and visually read the staff gage in the Parshall flume through which the water is flowing in order to calculate the flow. This new system is undoubtedly calibrated to the old staff gage, and likely radios the data in real-time, or perhaps daily.

Newly installed electronic gaging station next to Castle Creek above the town of Castle Valley. Note the metal Parshall flume box through which the water is flowing, away from the viewer in this image.

The sonic water level sensor at the upstream end of the Parshall flume. Note staff gage on side of flume.

The diverted water is claimed under three water rights granted in 1885, 1891 and 1933 for 2.0, 1.033 and 1.9172 cfs (cubic feet per second) respectively according to Utah DNR records.

UPDATE: An additional remote water gauging station has been installed on the 14-inch diameter iron pipe that transfers water from the point of diversion to the fields for irrigation lower in the valley. This is about 1.1 miles below the point of diversion seen above.

Racing up the rail...

the Bull Pup model rocket heads skyward at the Ken’s Lake Proving Ground this morning on an Aerotech F20-7W engine. It’s a very menacing scale replica of a short-range air-to-ground missile used by the US Navy during the 1960s and 1970s, but without the ordinance onboard, of course.