The document summarizes a field excursion through Canyon Country in the Colorado Plateau region. It describes the geographic features of the region including rivers, mountain ranges, and geological sections. It also discusses the climate, vegetation, rock formations, geological structures like joints, folds, and faults. The geological history of the region from the Precambrian era to present is outlined. Finally, it mentions some cultural features like petroglyphs carved by ancient peoples.

1. a photo essay by Brian Shoaf June 11-20, 2010

2. 3. Introduction 4. Geographic Features of Region 5. Location 6. Weather and Climate 7. Vegetation 8. Vegetation (continued) 9. Rock Strata Chart 10. Rock Strata Pictures 11. Joints 12. Folds 13. Faults 14. Geologic History Summary 15. Cultures 16. Petroglyphs vs. Pictographs 17. Pictures From the Field 18. Works Cited Climbing slick rock at Devil’s Garden (Personal Photo)

3. 2010 Canyon Country Field Excursion Geology Team (c ourtesy: Tom Bush, 2010 ) 3

4. The Plateau’s Canyon Country is defined as high desert plateaus with extremes in elevation provided by mountain peaks and deeply cut river gorges . High areas in the area include the La Sal, Abajo and Henry Mountain ranges, as well as the Circle Cliffs, the Monument and uplifts such as the Uncompahgre and San Rafael. The Plateau also has an intricate system made up of four rivers (Colorado, Green, San Juan and Dolores) that carved the majestic canyons we have today. The Colorado is the biggest, spanning 1,450 miles. There are seven separate geographical sections of the region: Uinta Basin High Plateaus Grand Canyon Navajo Datil-Mogollon Acoma-Zuni Canyonlands

5. La Sal Mtns. Beyond Buck Canyon (Personal Photo)

6. The Colorado Plateau’s climate is arid to semi-arid due to its proximity to the Sierra Nevadas. Statistically, Spring and Fall are the driest seasons for the Plateau. Winter is often ridden with storms and snow due to moist air from the Northwest where the Summers often see thunderstorms and other monsoonal weather patterns from the moist Southwestern air. The annual precipitation rate for most areas of the Plateau sit at and around 10%. This rate varies for higher-lying areas (8,000 ft. +, excluding mountains) with an average of 20-25 inches. Mountain areas see around 35 inches of precipitation annually. The weather was hot and arid during the Excursion for the most part. Although we definitely witnessed some monsoonal weather activity (cough, cough… Delicate Arch). The weather during the trip was accurate for the early Summer months in the Plateau: rapid daytime heat, scattered rainfall, some monsoonal activity but generally hot throughout. Pre-storm/flash flood at Delicate Arch. Perfect example of Summer weather patterns for the Plateau Personal Photo)

7. Lichen on Sandstone (Personal Photo)

8. Cryptobiotic Soil Crust (Personal Photo)

9. 300 Ma 290 Ma 240 Ma 205 Ma 138 Ma 66 Ma 1.6 Ma Present Day Massive wind-blown sand dunes Braided streams Massive wind-blown sand dunes Tropical streams , lakes and swamps Tropical tidal flats Cutler Fm. Includes: White Rim Ss (Wind blown beach sands), Organ Rock (Marine lowlands), Cedar Mesa Ss (Near shore sand dunes interfering with periodic floods) and the Lower Cutler Fm (Shallow seas) Evaporites from reoccurring seas flows in region Quaternary “ Work in progress” Deposits Tertiary La Sal Mtns. Abajo Mtns. Cretaceous Mancos Shale Dakota Sandstone Jurassic Morrison Fm Entrada Sandstone Carmel Fm. Navajo Sandstone Kayenta Fm. Wingate Sandstone Triassic Chinle Fm Moenkopi Fm Permian Cutler Fm./Group Pennsylvanian Honaker Trail Fm Caprock Member (Paradox Fm)

10. Navajo Kayenta Wingate Chinle Moenkopi White Rim Ss Kayenta Fm Wingate Ss Chinle Fm Moenkopi Fm Cutler Fm The first photo (personal photo) shows the rock formations present on Moab Canyon . The second photo (personal photo) also shows the different rock formations visible from Dead Horse Point on the Gooseneck in the Colorado River. The Rocks labeled were the most common formations we observed and discussed about on the trip. These formations are in the positions they’re in today due to erosional , depositional and techtonic processes. Top: Moab Canyon (Personal Photo) Bottom: Gooseneck (Personal Photo)

11. Joints are fractures in brittle rock that essentially stretch beyond their limit. Joints differ from other Geologic Features because when formed, there is little to no lateral movement. Scientists classify Joints by how they were formed. The three most common types of Joints are Tectonic Joints, Unloading Joints and Cooling Joints. In the picture to the right, you can see the Fins behind Tom at the Fiery Furnace. Fins are formed from jointed Entrada Sandstone that becomes weathered. (Personal Photo)

12. Folds are formed from flat rock, often sedimentary strata that bend and curve. The form under conditions of stress, temperature, hydrostatic pressure and pore pressure. We learned about several different classifications of Folds: Anticline Syncline Monocline Upheaval Dome in the heart of Canyonlands, is either an impact crater or a salt anticline, either way, the structure of the Dome includes an anticline near the center of the dome and a syncline on the outer parts. (USGS) (USGS)

13. Faults are formed by surface movement due to internal forces that cause plates to move. On the excursion, we observed the Moab Fault , which is an extensional fault. An extensional fault vertically thins while it’s horizontally extending portions of the earths lithosphere. So Essentially, the east side of the fault went up and the west side went down. We know this because Navajo Sandstone lies on the fault. The movement of the fault caused the Navajo Sandstone (which is normally above Wingate) to sink. Moab Fault (Personal Photo) (USGS)

14. The Geologic timeline of Canyon Country dates back to Precambrian times. 4,600 million years ago, the Crystalline basement of North America formed because of a collision between two ancient continents. This collision formed the bases of mountains and other geologically significant formations. Later on in this time period, Depositions produced the Grand Canyon Supergroup which led to The Great Unconformity, a process caused by uplifts, faultings and other erosional processes. From the Cambrian Period through the early part of the Pennsylvanian period, the Colorado Plateau saw continued processes of marine deposition in the area because of seas that would come and go throughout time. These marine depositions helped the erosional process of the Plateau. Meantime, the Paradox Basin produced different layers of salt in and around what is now Arches. Towards the end of the Pennsylvanian period, Pangaea, the supercontinent broke apart. The North American tectonic boundary is created. The Triassic period brought with it the development of nonmarine conditions . Through part of the Jurassic, different kinds of sands, conglomerates, and other sediments flow into the area forming Moenkopi, Chinle, Wingate and Kayenta formations. The Tertiary period brought with it the Laramide Orogeny which caused wide-spread faulting and uplifts of the region. River systems also began carving canyons into the Plateau, which is still happening to this day. So far in the Quaternary period, the Plateau continues to lift while the rivers continue carving the rock.

15. Roadside Ruin (Personal Photo)

16. Petroglyphs and Pictographs were both forms of art on rock by ancient peoples. Petroglyphs were carved or engraved onto the rock, while Pictographs were painted . We didn’t see any Pictographs while on the trip, but we saw several examples of Petroglyphs. To the right is Newspaper Rock . Located in Canyonlands, this well-preserved time capsule shows Petroglyphs carved by the Anasazi, Navajo and Fremont peoples. The carvings are thought to have been by only spiritual leaders of the tribes. Meaning behind them are unknown. Newspaper Rock (Personal Photo)

18. Chronic, Halka, 1988, Pages of Stone: Grand Canyon and the Plateau Country , the Mountaineers, Seattle Compton, R.R., 1985, Geology in the Field , John Wiley & Sons, New York Shue, Jerry, Neal Herbert, and Barbara Webb. Canyonlands Geology: A Visual Toolkit , Moab, UT : Canyonlands Natural History Association, 2010. Print. Canyonlands Cultural History , Canyonlands Natural History Association, 09/2007. Print. Land Use History of the Colorado Plateau . Northern Arizona University, Web. 7 July 2010. <http://cpluhna.nau.edu/>. &quot;Arches National Park, Utah.&quot; Geology of National Parks . Web. 09 July 2010. <http://3dparks.wr.usgs.gov/coloradoplateau/>. U.S. Geological Survey. Web . 09 July 2010. <http://www.usgs.gov/> .