Date of Award:
Master of Science (MS)
Tammy M. Rittenour
Tammy M. Rittenour
Joel L. Pederson
Evey G. Dalton
Today the climate in the southwestern United States is arid, characterized by desert landscapes and habitats, periods of drought, and arroyo streams that frequently fill with, and erode, through fine riverbed sediments. A series of cliffs and benches rising from the Grand Canyon to the southern plateaus of Utah, known as the Grand Staircase - home to Kodachrome Basin State Park, Bryce Canyon, are a classical example of this environment as we know it today. However, a record spanning the past 300 thousand years is preserved on the steps of the staircase indicating periods in the past where the climate may have been much different, and more energetic streams would have flowed and eroded through the region. These records are preserved in piedmont and river gravels visible at heights of up to 175 meters above modern-day river valleys.
A piedmont is a transitional area of a landscape between a steep front and the relatively less steep terrain below. Early piedmont and river gravels found along the steps of the Grand Staircase preserve a record of river position and energy over geologic time. The focus of this research was: to define to what extent this record was preserved, how many episodes of landscape change could be reconstructed, when that landscape change occurred, and what the main cause may have been for these episodes of change. This type of research contributes to the broader understanding of how and when landscapes may or may not respond to climate, a fundamental driver for landscape change, and how we can continue to tie landscape records to past, present, and future climate events.
Throughout the Grand Staircase three main levels of these gravel records were identified which mark at least three distinct periods of pronounced erosion across the region. Data from these gravels indicate that episodic and cyclical changes in climate, between wet and cool and warm and dry, over the last 300 thousand years, has been the primary cause of landscape changes in this region of the southwestern United States.
Short, Alexander K., "Late Pleistocene Piedmont Records in the Grand Staircase Region, Southern Utah" (2022). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 8651.
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