Bend Pumice

To begin, the mouth of the canyon features a hilly landscape with scars from landslides created from the uplifting of land by the Wasatch Fault. The fault, responsible for the creation of the Wasatch Mountains 25 million years ago, is a normal fault (Eldredge, 2014). Unlike some faults, vertical movement of the terrain is limited and slippage only occurs every several hundred or thousand years. Signs of the fault at work can be seen through the mouth of the canyon with the orange Tintic Quartzite which is dated back to the Cambrian Age. Layered beneath the quartzite is tillite from the Precambrian Age. To the west and separate from the Quartzite and tillite by the Wasatch Vault are limestone sections from the Missippian Age. (Rigby, Hintze, 1968, pg 23).

The cataclysmic eruption which caused the collapse of the caldera and the deposition of the Bishop Tuff was an explosive, fast event. It ejected coarsely porphyritic biotite rhyolitic ash and viscous lava with an approximate silica content of 76 percent. The total ejecta came to about 600

Sims et al. (1989) synthesized U-Pb zircon ages for the Pembine-Wausau terrane. Sims concluded that the volcanic rocks were generated from around 1889 to 1860 Ma as island arcs and closed back-arc basins above the south-dipping subduction zone (Niagara fault zone). Granitoid rocks in the terrane, emplaced from around 1870 to 1760 Ma, are mainly granodiorite and tonalite but include gabbro, diorite, and granite. These developed as island arcs above the Eau Pleine shear zone. The Niagara fault zone contains a relict ophiolite, suggesting that the rocks in the Pembine-Wausau terrane probably accumulated on

Next, we can see that the rock displays a subtle porphyritic texture with plagioclase comprising the phenocrysts. The overall texture of the surrounding groundmass is granoblastic equigranular. Under thin section we also see a weakly defined foliation evidenced in the preferential alignment of actinolite grains and to a lesser extent chlorite grains. Undulose extinction is also observed in quartz indicating the rock was subject to deformation. The normalized quartz, alkali-feldspar, and plagioclase (QAP) values of this rock indicate that it is classified as a grano-diorite according to the IUGS QAPF classification system which is consistent with the hand sample interpretation.

Many millions of years ago the Sierra Nevada was filled with ocean water until sediments began collecting and formed mountain ranges. Over a large period of time, the mountains began to wear out and became immersed in the ocean once again. Many different particles and materials began to make layers and created the first mountain system. After the Jurassic era, “…new strata were folded and crumpled and invaded by molten granite from below” (Beatty, 1943). A large

Our third stop was along the interstate, right between two formations of Washita Valley. The formation on the north of us was represented by Pennsylvanian Collings Ranch Conglomerate (around 350 million years old), which is shown with blue color on the map and the formation on the south of us was represented by Ordovician Kindblade Limestone (around 450mil years old), shown by the pink color on the map. There is a huge time gap between these two formations. The Collings Ranch Conglomerate is outstandingly exposed along Interstate 35 near the top of Arbuckle Mountains. It was formed during late Pennsylvanian and is slightly younger than Devil’s Kitchen Conglomerate. Large size of grains, conglomerate boulders and cobbles, indicate high energy

At the beginning of the Tertiary, there is a layer of andesite breccia -a fast cooling extrusive rock that has not traveled far from its original deposition. This indicates a volcanic depositional environment. This formation was then intruded by intrusive slower cooling rocks that create a noncomformity between it and the Walker formation. The tuff breccia in the Walker formation is consistent with the same depositional environment as the andesite breccia formation as they are both extrusive rocks. It is possible that there was an eruption from a volcano that deposited the highly viscous andesite rocks followed by slower falling ash, which was then

“Sedimentary Rocks.” Living with Volcanic Past. http://vulcan.wr.usgs.gov/LivingWith/VolcanicPast/Notes/sedimentary_rocks.html (accessed May 23, 2012). Stafford, Orin Fletcher. The Mineral Resources and Mineral Industry of Oregon for 1903.

is characterized by increased sediment yield from hillslopes destabilized by vegetation change resulting from climatic warming and drying (Bull, 1991; McFadden and McAuliffe, 1997). In the Zuni Salt Lake piedmont area, vegetation change and hillslope runoff-sediment yield during this transition would have been further disrupted by pyroclastic airfall and wildfires associated with eruptions at Zuni Salt Lake maar and Cerro Pomo cinder cone during the ~13.5¬–11.5 ka interval (Appendix A). Rates of fan deposition immediately after the eruptions were probably quite accelerated; however, by ~10.3 ka (the age of the oldest piedmont fan deposits exposed), fan aggradation was not particularly high (~2 m/ka). Early Holocene valley floodplains in the Carrizo Wash watershed, at least after ~9 ka, are characterized by slow aggradation of clay-rich alluvium. This suggests that most sediment eroded from the upland slopes during the early Holocene was stored on piedmonts as alluvial fan deposits, with a relatively minor amount of fine sediment reaching the valley floors. Early Holocene floodplains were therefore probably relatively stable, slowly aggrading, and densely vegetated

This dissertation is organized into three separate studies (appendices) that I plan to publish in peer-reviewed journals. The first appendix presents a study that establishes a latest Pleistocene age for volcanic eruptions at Zuni Salt Lake. The second appendix evaluates the hypothesis that the late Holocene hydroclimatic history of spring discharge at Cienega Amarilla is driven largely by variations in El Niño frequency and intensity and the resultant variations in winter precipitation. The third appendix examines the nature and timing of fluvial geomorphic change in mid-elevation valley and piedmont areas of the Carrizo Wash watershed and identifies the climatic factors driving this landscape change. Each of these appendices is described in more detail below.

Tuff* (‘’The layers of ash and dust which are deposited for some distance around a volcano, and which build its cone, become hardened into rocks which are called Tuffs. All such deposits are called pyroclastic (meaning “fire broken”), a name referring to their mode of origin. They are not igneous rocks’’. (Blyth, 1974)

About 90% of the Lava Beds is Basaltic. The other parts of the Lava Beds are Andesite. There are also parts of Tuff at the monument. There are large amounts of obsidian and pumice at the monument.

A swarm of aplite barriers, identified with the quartz diorite, is meddlesome into the contact zone. The Vermont quartz diorite is barged in by the Feliz granodiorite, a monstrous molten shake, which goes in organization from quartz diorite toquartz monzonlte. The sporadic, granulated and slickensides con-respect with the Vermont quartz diorite plutonic body and with the changeable shake complex is deciphered as importance interruption by an about strong gem charged magma. A blame piece of foliated quartz diorite Lar pluton is uncovered in the northeastern part of the range. The foliation, which is essentially because of adjusted, circle formed totals of biotite, is presumably aprimary magmatic stream structure. Various sporadic embankments of malchite and of basalt are nosy into the Lar quartz

The Purisima Formation is extensively allocated “in central California from coastal exposures at Point Reyes in Marin County to more extensive exposures in the Santa Cruz Mountains from the coast in San Mateo and Santa Cruz Counties inland to the San Andreas Fault.” These scattered visible rock formations are part of the Purisima Formation because they all share a few specific characteristics: They all have interbedded mudstone, siltstones, and very fine-grained sandstones, with abundant shell debris. The Purisima formation was created “about 3 to 7 million years ago during the late Miocene and the Pliocene through a 4 million year period of deposition: The deposited rocks record a shift from deeper offshore conditions (primarily siltstone

Following the end of Laramide crustal shortening and Palaeogene magmatism, the initiation of the development of the Rio Grande rift occurred between 31-28 million years ago in southern New Mexico (Berglund et al., 2012).. This rifting propagated northward to northern New Mexico (27-25 million years ago) and Colorado (27-26 Million years ago) (Crow, et.al., 2011). Early crustal extension involved low-angle faulting that formed broad basins and predates magmatism at the rift axis. This early- phase development of the Rio Grande rift lasted for 10 to 12 million years and was followed by a lull in volcanic activity between 17 and 14 Million years ago. This period of quiescence is apparent throughout the whole of the western USA, and it marks a change from volcanism that was dominated by calc-alkaline rhyolites and andesites to bimodal assemblages of basalt and rhyolite. It also marks a change in direction of crustal extension from WSW-ENE to E-W, that was accompanied by a decrease in the width of the zone of