A field trip to observe features of Lake Bonneville, mountain glaciation, and Great Salt Lake near Salt Lake City, Utah, USA

2021 ◽  
pp. 71-94
Author(s):  
Charles G. (Jack) Oviatt ◽  
Genevieve Atwood ◽  
Benjamin J.C. Laabs ◽  
Paul W. Jewell ◽  
Harry M. Jol

ABSTRACT On this field trip we visit three sites in the Salt Lake Valley, Utah, USA, where we examine the geomorphology of the Bonneville shoreline, the history of glaciation in the Wasatch Range, and shorezone geomorphology of Great Salt Lake. Stop 1 is at Steep Mountain bench, adjacent to Point of the Mountain in the Traverse Mountains, where the Bonneville shoreline is well developed and we can examine geomorphic evidence for the behavior of Lake Bonneville at its highest levels. At Stop 2 at the mouths of Little Cottonwood and Bells Canyons in the Wasatch Range, we examine geochronologic and geomorphic evidence for the interaction of mountain glaciers with Lake Bonneville. At the Great Salt Lake at Stop 3, we can examine modern processes and evidence of the Holocene history of the lake, and appreciate how Lake Bonneville and Great Salt Lake are two end members of a long-lived lacustrine system in one of the tectonically generated basins of the Great Basin.

2007 ◽  
Vol 46 (2) ◽  
pp. 196-211 ◽  
Author(s):  
Daniel E. Zumpfe ◽  
John D. Horel

Abstract Winds at the Salt Lake City International Airport (SLC) during the April–October period from 1948 to 2003 have been observed to shift to the north (up-valley direction) between late morning and afternoon on over 70% of the days without precipitation. Lake-breeze fronts that develop as a result of the differential heating between the air over the nearby Great Salt Lake and that over the lake’s surroundings are observed at SLC only a few times each month. Fewer lake-breeze fronts are observed during late July–early September than before or after that period. Interannual fluctuations in the areal extent of the shallow Great Salt Lake contribute to year-to-year variations in the number of lake-breeze frontal passages at SLC. Data collected during the Vertical Transport and Mixing Experiment (VTMX) of October 2000 are used to examine the structure and evolution of a lake-breeze front that moved through the Salt Lake Valley on 17 October. The onset of upslope and up-valley winds occurred within the valley prior to the passage of the lake-breeze front. The lake-breeze front moved at roughly 3 m s−1 up the valley and was characterized near the surface by an abrupt increase in wind speed and dewpoint temperature over a distance of 3–4 km. Rapid vertical mixing of aerosols at the top of the 600–800-m-deep boundary layer was evident as the front passed.


2010 ◽  
Vol 138 (7) ◽  
pp. 2528-2545 ◽  
Author(s):  
Gregory L. West ◽  
W. James Steenburgh

Abstract High-resolution analyses and MesoWest surface observations are used to examine the life cycle and mesoscale frontal structure of the “Tax Day Storm,” an intermountain cyclone that produced the second lowest sea level pressure observed in Utah during the instrumented period and the strongest cold frontal passage at the Salt Lake City International Airport in the past 25 years. A key mesoscale surface feature contributing to the cyclone’s evolution is a confluence zone that extends downstream from the Sierra Nevada across the Great Basin. Strong contraction (i.e., deformation and convergence) within this Great Basin confluence zone (GBCZ) forms an airstream boundary that is initially nonfrontal but becomes the locus for surface frontogenesis as it collects and concentrates baroclinicity from the northern Great Basin, including that accompanying an approaching baroclinic trough. Evaporative and sublimational cooling from postfrontal precipitation, as well as cross-front contrasts in surface sensible heating, also play an important role, accounting for up to 40% of cross-front baroclinicity. As an upper-level cyclonic potential vorticity anomaly and quasigeostrophic forcing for ascent move over the Great Basin, cyclone development occurs along the GBCZ and developing cold front rather than within the Sierra Nevada lee trough, as might be inferred from classic models of lee cyclogenesis. Front–mountain interactions ultimately produce a very complex frontal evolution over the basin-and-range topography of northern Utah. The analysis further establishes the role of the GBCZ in intermountain frontogenesis and cyclone evolution. Recognition of this role is essential for improving the analysis and prediction of sensible weather changes produced by cold fronts and cyclones over the Intermountain West.


Author(s):  
Emily J. Kleber ◽  
Adam P. McKean ◽  
Adam I. Hiscock ◽  
Michael D. Hylland ◽  
Christian L. Hardwick ◽  
...  

Abstract The 18 March 2020 Mw 5.7 Magna, Utah, earthquake was the largest earthquake in Utah since the 1992 ML 5.8 St. George earthquake. The geologic setting of the Magna earthquake is well documented by recent geologic mapping at 1:24,000 scale and 1:62,500 scale at and near the epicenter northeast of Magna, Utah. Subsurface fault modeling from surficial geologic mapping, structural cross sections, deep borehole data, and geophysical data reveals a complex system of faulting concentrated in the hanging wall of the Weber and Salt Lake City segments of the Wasatch fault zone including the Harkers fault, the West Valley fault zone, and the newly interpreted Saltair graben. Based on geologic and geophysical data (seismic and gravity), we interpret the mainshock of the Magna earthquake as having occurred on a relatively gently dipping part of the Salt Lake City segment, with aftershocks concentrated in the Saltair graben and West Valley fault zone. Postearthquake rapid reconnaissance of geological effects of the Magna earthquake documented liquefaction near the earthquake epicenter, along the Jordan River, and along the Great Salt Lake shoreline. Subaerial and subaqueous sand boils were identified in regions with roadway infrastructure and artificial fill, whereas collapse features were noted along the shores of the Great Salt Lake. Potential syneresis cracking and pooling in large areas indicated fluctuating groundwater likely related to earthquake ground shaking. The moderate magnitude of the Magna earthquake and minimal geological effects highlight the critical importance of earthquake research from multidisciplinary fields in the geosciences and preparedness on the Wasatch Front.


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