Earthly Musings – My Travel and Geology Blog: An Autumn River Trip Through Desolation and Gray Canyons on the Green River, Utah

Over the last week of September, I served as a geologic interpreter on a six day river journey by way of Desolation and Grey canyons on the Inexperienced River in Utah. This was a beautiful time of yr because the hordes of mosquitoes had already flown south the autumn colours have been starting to grace the cottonwood bushes and the temperatures have been heat within the day and funky at evening. It is a incredible geologic transect by way of some comparatively younger rocks. Take a look.

The early morning mild was simply starting to fall on the Guide Cliffs

The Inexperienced River because it exits Desolation Canyon (backside) and enters Grey Canyon (high).  Word the massive fan coming into the river channel from Three Fords Canyon on the left. It has pushed the river to the best (west) and remnant bounders washed into the river type Three Fords Speedy. See a view of this huge fan from the bottom later in this put up.

View of a cut-off meander alongside the Inexperienced River – we hiked this loop later within the journey

We landed on Horse Mesa Bench, a outstanding stratigraphic marker mattress within the Inexperienced River Formation

There’s a 1.5 mile hike from the touchdown strip to the river – fabulous!

Nice views of the river on our hike – be aware the Horse Mesa Bench in the course of the escarpment (small, heart cliff face)

Word the hikers (high) and the shadows (backside)

On the river by way of the well-known Inexperienced River Formation

Paleogeographic map of the Colorado Plateau about 50 Ma

Dawn from camp on the Inexperienced River Formation

River reflections

Typical camp scene on stunning sandy seaside

As we moved downstream, the Colton Formation started to emerge from beneath the river

We visited some spectacular petroglyph panels on aspect hikes

Recall the aerial view of a cut-off meander within the fourth {photograph} of this put up. Right here, we’re mountain climbing within the loop of the deserted meander.

Panoramic view of the deserted meander close to Hen Rock – see the annotations subsequent picture

The yellow strains denote the outdated meander bend (dashed the place obscured behind the meander “island”)

The “downstream” a part of the Inexperienced River’s outdated channel. The doorway and exit of the meander are very near the fashionable mattress of he river, suggesting that the abandonment is comparatively current.

Implausible view of the Inexperienced River in Desolation Canyon. Inside the distant wall of the canyon, be aware the colour distinction between the decrease, reddish Colton Formation and the higher, lighter-colored Inexperienced River Formation.

One other stunning camp location – sleeping on these seashores is incredible!

The Colton is a largely fluvial and deltaic deposit that barely pre-dates the Inexperienced River lakes. Up to now, it was referred to as the Wasatch Formation however that nomenclature utilization is extra restricted to close the Wasatch entrance now. The Colton has an fascinating speculation  hooked up with it.

The Colton Formation is an arkosic sandstone and mudstone (which means it comprises plentiful pink feldspar derived from granitic sources). It additionally yields zircon crystals that may be dated to their age of formation. Surprisingly, the one supply for these particular crystals is within the japanese Mojave Desert of southwestern Arizona and southeastern California. Davis et. al.  postulated {that a} continental scale river delivered the sediment from the realm of the Mojave Desert close to Blythe to the Uinta basin some 56 to 55 Ma. They referred to as it the California River (denoted by the thick dashed line). They made no declare for the precise place of the postulated river, solely that it will need to have flowed between the assorted Laramide upwarps (KU=Kaibab upwarp; MU=Monument upwarp; CCU=Circle Cliffs upwarp; SRS=San Rafael Swell). The scientific reference is: Davis, Stephen, J., (2010) “The Paleogene California River: Proof of Mojave-Uinta paleodrainage from U-Pb ages of detrital zircons”, Geol. Soc. of America, Geology, v. 38, no. 10, pp. 931-934.

Word the gradational transition between the reddish Colton Formation (beneath and largely forming slopes) and the lighter-colored Inexperienced River Formation above (ledges)

Because the slope-forming Colton Formation rises increased and turns into extra well-developed the canyon begins to widen out to present a lot broader views

Above Three Fords Speedy. A big particles fan from Three Fords Canyon pushes the river to the best (west) and remnants create the most important fast on the river (not seen).

Camp scene above Three Fords Speedy

Purple rock sundown from camp

Majestic buttes composed of the Colton Formation

One final upstream view of Desolation Canyon

The doorway to Grey Canyon – nonetheless older rocks emerge – the Mesa Verde Group

Our final nights’ camp offered a brief hike to a window by way of the rocks down to the Inexperienced River and our camp

Downstream view in Grey Canyon. The plateau caprock consists of the Bluecastle Sandstone Member of the Worth River Formation, the higher slope is named the Buck Tongue; the center cliff is the Castlegate Sandstone and the decrease half of the view consists of the Blackhawk Formation. All are Higher Cretaceous.

The journey ended with a view of Gunnison Butte, a well-known landmark within the space. This was a incredible journey (six days!) with an excellent group of “college students.”