Implications and Hydrographs for Two Pre-Bonneville Pluvial Lakes and Double Geosols from 14 OSL-IRSL Ages in Cache Valley, NE Bonneville Basin

In the northeastern Great Basin, USA, thirteen new optically stimulated luminescence (OSL) ages and one infrared stimulated luminescence (IRSL) age show that two deep pluvial lakes preceded the Bonneville lake cycle in Cache Valley during marine oxygen - isotope stages (MIS) 6 (123 - 191 ka) and 4 (56 - 71 ka), respectively. Our new data define quantitative hydrographs of the Little Valley and Cutler Dam lake cycles in both Cache Valley and the main Bonneville basin. In western Cache Valley, excavation of a faulted, east - plunging spit has sequentially exposed these deposits and overlying MIS 3 Fielding humid - over - arid double geosols that end westward at a strand of the east - dipping Dayton - Oxford normal - fault zone. Lithologically identical double paleosols in eastern Cache Valley overlie a variety of deposits, including dated Little Valley lake beds, and persist above the Bonneville shoreline. Six new ages show that the Little Valley lake cycle in Cache Valley began before 169 ka and ended after 143 ka, and its highest shoreline was above 1493 m. The >25 kyr duration of this pluvial lake cycle rivals the combined durations of the two subsequent lake cycles, during MIS 4 and MIS 2. The Cutler Dam lake rose at least to ~1450 m by ~67 ka in Cache Valley. In the type area in the main Bonneville basin, west of Cutler Nar-rows, four averaged IRSL dates from Cutler Dam lake beds show that the lake level there had dropped to ~1340 m by ~59 ka. The Little Valley lake rose at least 40 to 50 m above the local Provo shoreline whereas the Cutler Dam lake missed reaching the Provo shoreline by ~13 m.


Introduction
Our study emphasizes a Staker-Parson gravel pit that we call the Newton Hill pit, in west-central Cache Valley (Figures 1, 2).Our emphasis is primarily on pre-Bonneville lakes, so the literature on Lake Bonneville is cited only where pertinent.All altitudes are above mean sea level.Those within the Newton Hill pit are tied to an altitude at a nearby section corner and based on electronic distance meter (EDM) and hand-level surveys.Altitudes of the original surface there and altitudes elsewhere are based on U.S Geological Survey 7.5-minute topographic maps, GPS readings, Caltopo Lidar, and Google Earth Pro.We report present altitudes without correction for post-Bonneville rebound or tectonics because Bonneville rebound is <10-20 m in our study area in Cache Valley and rebound of pre-Bonneville deposits cannot be computed without better pre-Bonneville hydrographs.

Age Control
We obtained 12 OSL (optically stimulated luminescence of quartz) and IRSL (infrared stimulated luminescence of feldspar) ages from the Newton Hill pit, one from the SE part of Hyde Park, Utah, and one from Muley Hill in Millville, Utah.The latter two are in the east side of Cache Valley (Figures 1A, 1B; Table 1).A metal tube was pounded horizontally into the sediment except at Muley Hill, where matrix sand was collected from gravel beds using double black plastic bags under red light at night.Surrounding sediment was obtained to establish both background data and moisture content for each sample.Lab analyses at the Utah State University OSL lab by Michelle Nelson were done under the supervision of Tammy Rittenour, with standard procedures outlined in the notes of Appendix 1.
Recalibration and new standards for OSL dating changed the OSL and IRSL dates reported earlier by us (Oaks and others, 2014(Oaks and others, , 2019(Oaks and others, , 2020)).One previous pluvial lake bed dated at ~96 ka (N = 1; the Newton Hill beds), instead formed during the earlier Little Valley Lake cycle (sample USU-1083; Table 1; Appendix 1).

Construction of Map and Geologic Cross Sections
The evolving exposures of the pit walls were surveyed with a Leica model TC600 laser total station in   2016.Thereafter, new contacts were surveyed with an Abney hand level from the EDM base station.These data, combined with our 12 OSL and IRSL ages from the central and western parts of the pit, were used to construct a map and four composite stratigraphic sections across much of the Newton Hill pit (Figures 3,  4).Correlations are tied to: (1) continuous and isolated exposures of the Fielding double geosols (Oviatt and McCoy, 1988)

Quantitative Hydrographs
Our new data (Table 1) and prior AAR data (Appendices 2, 3, 4) and thermoluminescence (TL) data, tied to altitudes (Appendix 5), constrain our quantitative hydrographs (Figure 5) of the Cutler Dam and Little Valley lake cycles in both Cache Valley and the main Bonneville basin.These hydrographs update schematic plots of Scott andothers (1982, 1983), McCoy (1987), Oviatt and others (1987), and Hart and others (2004), for these two pre-Bonneville lake cycles.Our results align with far more detailed hydrographs of the Bonneville lake cycle in the main Bonneville basin of Currey and Oviatt (1985), Oviatt and others (1992), Nelson (2012), and Oviatt (2015Oviatt ( , 2020)).Our data also constrain the pre-Bonneville, post-Cutler Dam age of newly identified red-over-white double Fielding geosols in the Newton Hill pit and lithologically similar paleosols in eastern Cache Valley.

Overview of Newton Hill Gravel Pit
On the SE flank of Newton Hill, central Cache Valley, Utah (Figure 3), our ongoing studies have delineated the internal architecture of an east-plunging, nose-shaped compound spit deposited atop an eastsloping, eroded face of Little Valley gravel during the Cutler Dam and Bonneville lake cycles.The most continuous exposures lay between ~1408 m and ~1462 m, mostly below the prominent, higher Provo shoreline (Janecke andOaks, 2011a, 2011b) at ~1463 m at this locality.Scattered exposures continued to ~1487 m.Exposures in the south-central part of the pit in 2006 were so extensive that the key stratigraphic relations and the overall architecture of the deposits were unambiguous (Figure 6).The spit's original crest flattened uphill westward into a wave-cut and wave-built platform at the higher Provo shoreline of Lake Bonneville (Figure 2).The crest of the spit was parallel to and slightly north of the southern boundary of the gravel pit (Figure 6D).Pre-Bonneville sediment is mostly exposed in the central and western half of the gravel pit.

Stratigraphic Relationships
In the Newton Hill pit, Little Valley gravel is overlain by the upper red geosol at sample site USU-2490 (Figure 7A).At sample site USU-2491, there is no geosol between Little Valley pebbly sand and overlying Cutler Dam sandy mud (Figure 7B).At USU-1083 (Figures 4B, 4D) and at USU-857 (Figure 4A), Little Valley gravel is overlain by Bonneville deposits, with no geosol between.At USU-2895 Little Valley marl is overlain by a Fielding-like caliche paleosol beneath offshore Bonneville deposits.At USU-3202 Little Valley gravel is overlain by thin sediment of Cutler Dam lake cycle, then the upper Fielding geosol, beneath laminated fine-grained Bonneville deposits (Figures 4A, 4D).Although undated, at USU-1084 probable Little Valley gravel underlies a local channel with ashy sand under surficial gravels with modern soil.We did not find the base of the Little Valley deposits, nor identify pre-Little Valley units.Downward excavation ceased in the central part of the Newton Hill pit because of a noncommercial green marl 4 to 6 m thick according to two pit operators.
The Little Valley deposits are primarily pebble to cobble gravels and sandy gravels with low dips (Figure 7A).Discontinuous exposures west of the Dayton-Oxford fault strands reached at least 8 m thick.Locally there are thin marls and sand beds.
In Hyde Park, Utah, in eastern Cache Valley (Figure 1), at sample site USU-2895, a pale green Little Valley marl with a thin, calcareous, fine-to coarse sand lens is overlain by a white Bk paleosol 0.55 m thick, in turn overlain by a thin lag cobble gravel followed upward by 2.0 m of Bonneville light brown, thinly laminated, silty very fine sand with snails (cf.nearby exposure at Figure 8A).Elsewhere in eastern Cache Valley, weakly laminated to structureless marls and minor fine sands dominate probable Little Valley deposits.These undated older lake beds underlie the double Fielding geosols and Bonneville deposits, and persist at least up to ~1530 m, which is about 40 to 45 m below the local Bonneville shoreline (Figure 8B).and chrons,  and sources are from Table 1 and Appendices 2 and were revised from Oaks and others (2019)

Age Control (N=6)
Five exposures of pre-Bonneville lake gravels in the Newton Hill pit and one exposure in Hyde Park, Utah returned OSL and IRSL ages coeval with the Little Valley Lake cycle (MIS 6).The oldest age of ~169 ka (USU-2491) is from the north-central part of the Newton Hill pit, whereas the youngest age of ~143 ka (USU-2895) is from Hyde Park at ~1493 m.The latter is also the age determination from the highest elevation.The Little Valley lake cycle flooded Cache Valley to elevations well above ~1493 m, possibly as high as ~1530 m, and attained altitudes many tens of meters higher than expected (cf.Scott and others, 1983).The youngest beds dated in the Newton Hill pit (USU-1083; Table 1) are essentially the same age as that from Hyde Park.

Cutler Dam Lake Beds Stratigraphic Relationships
In the south-central part of the Newton Hill pit, east-sloping foresets of sandy, well-rounded, pebble to cobble gravels underlie the Fielding geosols.The foresets there were >6 m high and extended horizontally about 200 m (Figure 6A).To the north, exposures of these spit gravels are about 6 to 10 m thick and flatten into finer bottomset beds (Figure 7B).There are sharp erosional contacts locally within the foresets (Figure 6A).The highest exposures reach ~1443 m, but early photos (Figure 6B) and projection in Figure 4D suggest that the highest lake beds may have reached ~1450 m (Appendix 5).
Bedding in the S-central part of the pit and the shape of the overlying pink marl (Figure 3) indicate that the spit probably was mainly east-plunging, yet part of this spit also extended northward (Figures 4A,  4B, 4D, 6B).Gravels to the north intertongue with underlying green, silty, fine-sandy laminated marl 2 m thick (Figure 7B).Most gravel lenses there thin downward and pinch out to the north between intercalated marl layers that thin upward and pinch out to the south.Two fault or slump surfaces offset the gravels in the north.These offset the contact between topsets and foresets (Figure 7B).

Age Control (N=2)
Two samples from this deposit in the southcentral part of the Newton Hill pit yielded OSL dates of ~67 ka (USU-856, -858).These are coeval with the Cutler Dam lake cycle and MIS 4 (Figures 3, 4, 5; Table 1).

Ashy Channel Fill
Near the former west margin of the Newton Hill pit, a white reworked ashy fine sand filled a scour below thin surficial gravel and modern soil, ~1483 m.Satellite imagery (8-11-2011) in Google Earth Pro shows this narrow channel trended NNW-SSE.Probable Little Valley beds below this channel dip ~4o west and roll over eastward to dip gently east.The upper part of the probable Little Valley beds are truncated eastward at the pre-Cutler Dam erosional face (Figure 7A).This subaerial channel fill yielded an OSL age of ~54 ka (USU-1084), during MIS 3 (Table 1; Figures 3, 4C).This is older than the upper Fielding geosol but younger than the Cutler Dam gravels exposed lower in the Newton Hill pit and the shallowwater Cutler Dam muds in the type area southwest of Cutler Narrows (Figure 5).

Double Fielding Geosols In Newton Hill Pit Stratigraphic Relationships
In the original south-central part of the pit, two successive geosols developed above and partly within the top of underlying gravel foresets of the Cutler Dam lake cycle (Figure 6A).This unit consists of an upper, humid-climate, red-weathering, loessdominated interval and a lower, arid-climate, white caliche interval.The contact between the two geosols is primarily erosional, but locally gradational.In one place the upper geosol is separated from overlying deep-water Bonneville deposits by a thin gravel wedge up to 1 m thick (Figure 6C).
The lower of the two geosols typically has only an eroded lower Bk horizon, up to 1.5 m thick, above the Cutler Dam foreset gravels.This geosol pinches out east and west of the south-central part of the pit, and does not reach the east strand of the Dayton-Oxford fault westward in the pit (Figures 6B, 6C).Calcite in the lower geosol penetrated down into the Cutler Dam foreset gravels beneath (Figure 6A).It has amalgamated subhorizontal stringers of carbonate and amorphous nodules.Pieces of the eroded caliche are common in the lower part of the red geosol above (Figure 8A).The eroded upper contact of the caliche has distinct channels up to 15 cm deep filled with, and overlain by, as much as 2.5 m of the red geosol.
The upper geosol is mainly loess and slightly pebbly loess, although locally it contains abundant colluvium.It has considerable organic material, exhibits downward displacement of clay, has a distinctive reddish soil hue (10R5.5/4),displays little cementation, and has a few vertical calcite stringers, but lacks caliche nodules except those reworked into the base (Figure 6C).Its top has a less prominent erosion surface than its base.This upper geosol thickens to 5 m or more westward, near the hanging wall of the Dayton-Oxford fault (Figures 6B, 7A), and locally on the north flank of the Cutler Dam spit, where the caliche geosol is absent (Figures 4A, 4D).There its upper part is colluvial gravelly mud overlying 2 to 3 layers of gravelly loess with weak subsoils.Locally in the north it pinches out eastward beneath a gray modern soil at the original surface of the pit.
Where absent in the east part of the pit, and locally in the north part of the pit, the upper contact of the double geosols is marked by a lag gravel or the green marl (Figures 4A, 4D) at the base of the Bonneville deposits above Cutler Dam foresets.Surveyed contacts of the top of the reddish geosol suggest that it probably rose at least to ~1463 m in the west part of the pit (Figures 4A, 4B, 4C).It descended to below ~1441 m in the SE part of the pit, and to below ~1444 m locally northward (Figures 3, 4D).Erosion probably removed these geosols from the lower and higher parts of the present Newton Hill pit before Bonneville deposits were laid down.The absence of the Fielding geosols in the footwall of the Dayton-Oxford fault makes it challenging to estimate the throw across the fault, although it must be >2 m.

Age Control (N = 1)
In the S-central part of the pit, the middle part of the red geosol, ~1444 m, contains a lens of sandy sediment that yielded an OSL age of ~39 ka (USU-855) (Figures 3, 4B, 6C).This dates to the penultimate interglacial, MIS 3c (Lisiecki and Raymo, 2005).

Double Geosols in Eastern Cache Valley
In Hyde Park and North Logan, Utah, in eastern Cache Valley, we found numerous examples of pre-Bonneville double paleosols in many trenches for utilities and in basement and landscape excavations (Figure 8B).These paleosols are essentially identical to those in the Newton Hill pit, with a red clay-rich paleosol over an eroded white caliche paleosol.Several of the lower exposures have only the eroded lower white Bk paleosol, locally with a very thin, eroded, red paleosol above.Detailed local mapping with an Abney hand level near sample site USU-2895 demonstrated an undulose paleotopography beneath the paleosol with lateral changes in the underlying sediments uphill and laterally.All exposures lie above the highest Cutler Dam deposits in the Newton Hill pit.
In eastern Cache Valley, either the double paleosol, loess deposits, or a gravel lag underlie the Bonne-ville offshore sand with snails (west, lower) and Bonneville gravel or post-Bonneville colluvial gravel (east, higher), respectively (Figure 8B).The white caliche paleosol overlies dated Little Valley marl (~143 ka; USU-2895) at ~1493 m in Hyde Park, and both paleosols overlie undated alluvial-fan debris flow deposits at ~1526 m in exposures farther east (Figure 8A).Exposures of these widespread double paleosols were recorded through a vertical range of at least 124 m and a horizontal separation of at least 2.7 km NNW -SSE (Figure 8B).The highest exposure, at ~1607 m, is above the Bonneville shoreline (41.78501, -111.77766).Our current concept of the spatial and stratigraphic relations of the lake cycles and intervening paleosols is shown in Figure 9.

Bonneville Lake Beds Stratigraphic Relationships
Bonneville deposits originally blanketed the spit in the area of the Newton Hill pit (Figure 2).In the southern exposures, topsets and foresets of sandy pebble to cobble gravels of the Bonneville lake cycle (Figure 6A) grade downward into finer bottomsets that overlie more than 3 m of transgressive deepwater marls and laminated silty sand (Figure 6C).Northward, where the pre-Bonneville relief was lower, deposition included lower green marls and a single higher pink marl that form distinctive marker beds (Figures 3, 4) between thicker Bonneville gravels (Figure 10).The pink marl is a calcareous, very fine sandy, clay-rich silt.It is plastic, weakly laminated, and thin (tens of cm thick).It is either pink throughout (oxidized reddish orange (5R7/2) or greenish-gray to whitish color at the base.It might be Gilbert's "white marl", which dates from the highstand of Lake Bonneville.Its red stain may be due to iron supplied by the proximal Bear River.
Locally, a lower green Bonneville marl directly overlies Cutler Dam deposits where the Fielding geosols are absent (Figures 4A, 4D), but there are other traceable pale greenish marls higher in the Bonneville sequence.Several marls produced low-angle slip surfaces that repeat layers within the Bonneville deposits in small slumps and slides (Figure 10).These might have been triggered by earthquakes, the Bonneville flood, or both.
These deep-water deposits sharply overlie an unconformity and the upper Fielding geosol (Figure 6B).A laminated silty sand lens in cobble gravel from the lower part of Bonneville deposits, in the central part of the pit, yielded a slightly younger OSL age of ~21 ka (USU-1082).There the Bonneville deposits directly overlie eroded Little Valley gravels (USU-1083) with no paleosol between (Figures 4B, 4D).A sand bed intertongued with northeast-dipping gravel beds in the north-central part of the pit yielded a post-flood Provo age of ~15 ka (USU-859) (Figure 3).At Muley Hill in Millville, Utah, gravel atop an eroded delta, at ~1550 m, between the Bonneville and Provo levels, yielded an age of ~21 ka (Table 1).

Subsurface Evidence of Pluvial Lakes
Drillers' logs from >1000 water wells across the center of Cache Valley southeast and east of Newton Hill document two gravelly layers and two clay-rich layers in the subsurface.An upper confining silty clay (marl?) unit ~18 m thick, an intervening, persistent gravel unit ~9 m thick, and a lower confining silty clay unit ~9 m thick, overlie thick underlying gravel and sand (Williams, 1962;Bjorklund and McGreevy, 1971;Clyde and others, 1984;Kariya and others, 1994;Robinson, 1999;Thomas and others, 2011).Figure 11 shows these relations along part of U.S.
Highways 89/91 (Figure 1).Within the upper confining layer there are typically two horizons of nonpersistent gravels associated laterally with oxidized brown silty clays.Gray, blue, or black silty clays lie both above and below these gravel and oxidized intervals.The lower confining layer also encloses lenses of gravels and related oxidized horizons.These clays overlie sandy gravels of Pleistocene age and underlying older gravels in the Salt Lake Formation that cumulatively reach ~150 m to 300 m thick between Smithfield, Wellsville, and Hyrum (Robinson, 1999) (Figure 1A).These coarse sediments are the Principal Aquifer in Cache Valley (Figure 11).
The unoxidized clays probably are deep-water lake deposits.They likely are coeval with the three lacustrine deposits in the Newton Hill pit, and perhaps earlier pluvial lakes in the main Bonneville basin (Williams, 1962), including older lake cycles identified in the Saltair and Burmester cores (Eardley andGvosdetsky, 1960, Eardley andothers, 1973;Williams, 1994;Oviatt and others, 1999).The gravels and oxidized muds at distinct levels within the unoxidized muds either indicate interglacial epochs or major oscillations within long pluvials (Williams, 1962; this study).In the southwest part of Figure 11, a persistent gravel within the upper confining layer may be a chance intersection laterally along a former stream channel.Elsewhere in Cache Valley, the underlying Salt Lake Formation has many different lithologies.These include conglomerates, tuffaceous green (zeolitebearing) to dark and light gray shales, sandstones, siltstones, thick to thin, pale brown very fine crystalline (micritic) limestones, oolitic limestones, and diabase (Adamson and others, 1955;Goessel and others, 1999;Oaks and others, 1999;Janecke and Evans, 1999;Janecke and others, 2003).These distinctive lithologies are repeated by extensional folds and normal faults, so that the Salt Lake Formation commonly exhibits tilts.Dips as high as 78° distinguish the Salt Lake Formation from the overlying Quaternary deposits (Oaks, 2000).

Overview of the Hydrographs
Data for the hydrographs in Figure 5 are in Table 1 and Appendices 1 to 5. The hydrographs for Cache Valley and the main Bonneville basin show good correlation of lake highstands and lowstands in both basins and also with the O-isotope marine record of climatic fluctuations for MIS 6 through MIS 1.The Little Valley lake rose higher than the local Provo shoreline, whereas the Cutler Dam lake cycle did not rise quite as high (Figure 9).
The MIS 5 interglacial persisted for ~55 kyr, twice as long as the ~27 kyr-long MIS3 interglacial.The isotopic data also suggest that MIS 5 was warmer than MIS 3 (Figure 5).Yet there are no distinct, widespread soils associated with MIS 5 in Cache Valley, and the only possible exceptions elsewhere are the Promontory/Dimple Dell geosols in the Little Valley pit and other parts of the main Bonneville basin (Scott and others, 1983).It is noteworthy that well-dated Fielding humid soil and the underlying arid soil, both of which are widespread in Cache Valley, formed during the relatively short and mild interglacial MIS 3 before the Bonneville lake cycle, yet they are exceptionally thick and robust paleosols (Figures 3,5,6,8).
The lake was at least 150 m deep during the 68 to 67 ka part of the Cutler Dam lake cycle, in the early part of MIS 4, yet it coincided with a relatively minor oscillation in the climate record (Lisiecki and Raymo, 2005).This seems anomalous compared with the climatic and hydrologic conditions that favored deep lakes during MIS 6 and MIS2.The oscillations of benthic marine isotopes are only about 60% as intense during MIS 4 as during MIS 6 and MIS2 (Figure 5).
Perhaps deep lakes can form with less Milankovitch forcing than glaciers.Alternatively, added water may have begun to flow across a waterfall in Oneida Narrows into Cache Valley then, followed ~20 kyr later by the complete, final diversion of the Bear River into the Bonneville basin (Pederson and others, 2016).A complex history of incision of Oneida Narrows is suggested by one or more widespread subsurface gravels below a mud layer under surficial gravel from Oneida Narrows through several kilometers downstream in drillers' logs of water wells (Oaks, 2010).

Little Valley Lake Cycle
The age and duration of the Little Valley lake cycle is constrained by our six new absolute ages, five published AAR estimates, one published TL age, and one extrapolation from the estimated rate of formation of the overlying Promontory paleosol (Figure 5; Table 1; Appendices 2, 3, 4).Combination of all the data for the main Bonneville basin (blue dashes in Figure 5) suggests that the Little Valley lake cycle might have persisted 20-30 ky into interglacial MIS 5.However, an end closer to 123 ka, at the end of MIS stage 6, is more likely based on the climate record and our new absolute ages (preferred model in Figure 5).
In the main Bonneville basin, altitude control for the Little Valley lake cycle is limited, with some corrected for rebound, others not (McCoy, 1981(McCoy, , 1987;;Scott andothers, 1982, 1983).The highest probable but undated Little Valley gravels in the main Bonneville basin are at ~1512 m in the Geneva quarry at Point of the Mountain, south of Salt Lake City (Scott and others, 1983) and at ~1517 m in the Little Valley pit, where they were initially misidentified as "Alpine" by Morrison (1965Morrison ( , 1966) ) and reinterpreted by Scott and others (1983).These older lake beds are about half way between the local Bonneville and Provo shorelines (Scott and others, 1983).
In Cache Valley the highest dated Little Valley deposits, at ~1493 m in Hyde Park are sandy, weakly laminated marl, and undated deposits traced uphill from dated beds in the upper Newton Hill pit, at ~1483 m.These also lie between the Bonneville and Provo shorelines.Thus, the highest level attained by the Little Valley pluvial lake is not certain, but elevation ranges are high and roughly similar in both basins (Appendix 5).Active tectonics in both basins may have raised or lowered individual sites, which is especially critical for older lakes.Further discovery of higher shoreline exposures and absolute ages are needed to determine if the actual highest water levels of the Little Valley lake cycle were the same or different across Cutler Narrows.

Cutler Dam Lake Cycle
Our ages of Cutler Dam deposits in Cache Valley confirm that this pluvial lake rose at least 110 m above that of marshy sediments in the type area (Oviatt andMcCoy, 1988, 1992) in the main Bonneville basin SW of Cutler Narrows (Figures 1B, 6B; Appendix 5).Two IRSL ages from Cutler Dam deposits and two from the base of the Fielding geosol in the type area averaged ~59 ka (Kaufman and others, 2001).This is younger than the average of ~67 ka for two OSL ages near the higher level in Cache Valley.Although the error limits of the ages from both sites overlap slightly (Figure 5; Table 1; Appendix 2), the central ages differ.These data may indicate a drop to the lower level near the end of MIS 4, consistent with the climatic data (Figure 5).
Additional OSL age control from distal Cutler Dam beds in the Newton Hill pit would further constrain the hydrograph in Figure 5. Re-dating lake beds between those of the Little Valley and Bonneville lake cycles in Hansel Valley (Robison and McCalpin, 1987) with OSL might show that they are coeval with the Cutler Dam lake cycle, which seems likely.

Fielding Double Geosols
Our dated samples of the upper Fielding geosol and the ashy sand channel fill indicate that subaerial deposition replaced the Cutler Dam lake after the end of MIS 4, at ~56 ka.Our double geosols are similar to the sequence described by Kaufman and others (2001, p. 324) in the type area SW of Cutler Narrows.Their Figure 2 showed three successive geosols that comprise their Fielding geosol, described in the figure as: "Massive red-brown silt and clay; at least three petrocalcic horizons, each topped by a snail-rich horizon; oxidized rootlets on blocky weathered surfaces".
The similarity of our double geosols to descriptions of the Promontory and Dimple Dell double paleosols in the Little Valley pit (Morrison,1965) is also striking.There, a lower caliche geosol and an upper red (10YR) loess-derived geosol lie between Little Valley and Bonneville deposits.All exposures there are above the highest known Cutler Dam lake beds in Cache Valley.
Despite the similar lithologic features and nearly identical stratigraphic relationships, the Promontory and Dimple Dell geosols are interpreted to be much older, ~104 ka (Scott and others, 1983; their Table 5).If so, the Promontory and Dimple Dell palesols are significantly older than the Fielding geosols.Absolute ages are needed to resolve this puzzle.
An OSL age is needed in Hyde Park within the double paleosols there, to determine if these paleosols are definitely coeval with, or differ in age from, the dated upper Fielding geosol in the Newton Hill pit.

Bonneville Lake Cycle
The final diversion of the Bear River into Cache Valley ~ 45 to 55 ka (Pederson and others, 2016) was too late to raise the Cutler Dam lake, and all earlier lakes, above a divide ~2 km north of Red Rock Pass, at the north end of Cache Valley (Gilbert, 1890) (Figure 1A).Its final addition raised Lake Bonneville higher than earlier lakes, to overtop that divide (Bright, 1963;Hochberg, 1996;Bouchard and others, 1998;Link and others, 1999;Janecke and Oaks, 2014;Pederson and others, 2016;Utley, 2017).An earlier overflow across Oneida Narrows (Oaks, 2010) may have raised the Cutler Dam lake above that expected from the O-isotope data (Figure 5).
Our two OSL ages of ~21 ka in the Newton Hill pit, at ~1422 m and ~1447 m, lie within the wide envelope of 14 C dates with confidence intervals for the rising limb of the Bonneville transgression in the main Bonneville basin (cf.Oviatt, 2015Oviatt, , 2020)).However, both are minimum depths for the lake level at those times.Furthermore, well-rounded gravels at Muley Hill, with an age of ~21 ka, at ~1550 m elevation, is close to the local Bonneville shoreline at ~1573 m (Figure 9), and above the Oviatt envelope of dates.Janecke and others (2013) obtained a 14 C age ~22 ka in nearshore sands at ~1500 m in a gravel pit at the mouth of Green Canyon in eastern Cache Valley, between Logan River and City Creek (Figure 1A), somewhat above the Oviatt envelope.
Thus, although the age-altitude data from Cache Valley plotted in Figure 5 might suggest a slightly earlier rise of Lake Bonneville during its transgression, the data do not differ enough from those compiled in Oviatt (2015Oviatt ( , 2020) ) to be compelling.More precise and diverse age control is needed to improve the earlier curve for Lake Bonneville, which was compiled from 14 C age determinations.
We believe that a prolonged Bonneville highstand during oscillatory (?) overflow to the north, is needed to explain high, steep, wave-cut bedrock cliffs at the Bonneville shoreline throughout the Bonneville basin (Janecke and others, 2019).Significant time is also required to backfill Gem Valley, Oneida Narrows, lower Bear River-Mink Creek Canyon, and finally deposit the large Bonneville delta north of Preston, Idaho, with a surface area of >125 km 2 in Cache Valley (Figures 1A, 1B).The Bonneville delta of the Bear River back-filled a reach that was ~55 km long, between Gem Valley and northeast Cache Valley (Janecke and Oaks, 2011b).

Implications for Incision of Cutler Narrows
It is unclear if Cutler Narrows was incised well below the ~1450 m Cutler Dam gravels of Cache Valley before the Bonneville flood because the evidence is incomplete and inconclusive.Sr isotopes indicate likely entry of water of the Bear River west of Cutler Narrows during both the Little Valley and Cutler Dam lake cycles (Hart and others, 2004).The flow could have been through a fully incised Cutler Narrows, with lakes at the same or similar levels on both sides, or as flow across a lip near or slightly below the ~1450 m Cutler Dam gravel of Cache Valley that separated lakes with different levels.Although Oviatt andMcCoy (1988, 1992), Oviatt and others (1987), and Kaufman and others (2001) found no deep-water Cutler Dam deposits in ~15 m of shallow-water Cutler Dam deposits west of Cutler Narrows, such could be present in the subsurface there.
Several arguments suggest that deep incision almost to the modern level of the Bear River is a reasonable interpretation of the existing data.These arguments include: (1) the >4 Ma age of the east side of the horst block, so that considerable time was available to incise the canyon at Cutler Narrows; (2) the short and low canyon in Cutler Narrows, compared to dozens of deeper and longer canyons cut by streams with a fraction of the discharge nearby (e.g.Logan Canyon), which include some carved by now minor and intermittent streams (e.g.Weston Canyon); and (3) subsurface fluvial (?) sand and gravel deposits, hundreds of meters thick, that alternate with clay and silt that settled from lakes (Williams, 1962).This facies pattern continues from the Quaternary units down into the underlying Pliocene Salt Lake Formation (~12 to ~2[?] Ma; Goessel and others, 1999;Oaks and others, 1999;Janecke and others, 2003) (Figure 11).The thick and laterally continuous fluvial (?) gravels beneath the center of Cache Valley suggest protracted external drainage because continuous playa and lake deposits would have formed if there had been a long-lived barrier in Cutler Narrows.Williams (1962) also argued that external drainage during most of the Pleistocene is required to produce the consistently thin Quaternary deposits beneath Cache Valley.
To determine if pre-Little Valley lakes extended through Cutler Narrows and how high they reached relative to those in the main Bonneville basin, absolute ages are needed from more lake beds between the Provo and Bonneville shorelines in both basins.A continuous core where the Quaternary deposits are thickest in Cache Valley, perhaps near the location of Figure 11, could provide further age control.
Altogether, we conclude that the narrow, low horst between Cache Valley and the main Bonneville basin was probably breached early because it is neither high enough nor wide enough to separate high pluvial lakes for an extended period of time (Figure 1).Much, possibly nearly all, of the excavation of Cutler Narrows in bedrock probably took place before the Little Valley lake cycle (Oaks and others, 2014(Oaks and others, , 2019(Oaks and others, , 2020;;cf. Maw, 1968, Hunt, 1982).
Complete resolution could come from finding: (1) ~59 ka Cutler Dam shallow-water lake beds in Cache Valley near the same elevation as the Cutler Dam beds in the type section; or (2) high-elevation Cutler Dam beds in the main Bonneville basin that date from ~67 ka; or (3) that the dated Cutler Dam gravels between 1450 -1410 m in Cache Valley are coeval with the low-elevation shallow-water deposits in the main Bonneville basin.

CONCLUSIONS
Our 14 new OSL and IRSL ages establish the first evidence of Cutler Dam lake deposits and double Fielding geosols, and provide the first absolute ages of Little Valley deposits in Cache Valley.Our quantitative hydrographs show firm correlation of deposits in Cache Valley with the Little Valley (MIS 6), Cutler Dam (MIS 4), Fielding (MIS 3), and Bonneville (MIS 2) units in the main Bonneville basin.
None of our contacts between dated sediment of the Little Valley and Cutler Dam lake cycles preserve paleosols.In contrast, our double Fielding geosols lie between well-dated Cutler Dam and Bonneville deposits up to the highest near-shore gravel deposits of the Cutler Dam lake cycle in the Newton Hill pit (Figures 6, 7A).Higher in the Newton Hill pit and in Hyde Park (Figure 8A) double paleosols lie between the Little Valley and Bonneville deposits.Above the Bonneville shoreline in North Logan (Figures 8B, 9) they lie above pre-Bonneville loess and alluvial-fan deposits.These paleosols consistently exhibit an eroded arid-climate white calcic Bk horizon overlain by a loessic humid-climate red soil, and thus are provisionally correlated here with the dated Fielding geosols in the Newton Hill pit despite the absence of additional geochronology.
Drillers' logs of water wells identify two thick, confining clay-rich layers separated by a continuous gravel layer.These overlie thick gravels of the gravels of the Principal Aquifer of Cache Valley (Figure 11).Each confining clay sequence contains local gravels with adjacent oxidized clays that may indicate emergence due to oscillations within protracted lake cycles or interglacial episodes between pluvials.Lake deposits older than Little Valley may be present here.
The majority of incision of Cutler Narrows proba-bly predates the Little Valley lake cycle.Although the evidence for when Cutler Narrows was cut below the ~1450 m Cutler Dam deposits in Cache Valley is incomplete, we believe that the evidence supports early incision to near its present depth. A

Figure 1 .
Figure 1.A) Major features of the greater Cache Valley region, N-central Utah and SE Idaho.Green box outlines area in Figure 1 B. Red line NE from College Ward, south central Cache Valley, shows location of Figure 6.JH = Junction Hills; CBD = Cache Butte Divide.B) Landscape of Cache Valley area showing sites of pre-Bonneville deposits dated with AAR, OSL, and IRSL.Type area of Cutler Dam unit is along Bear River, SW of Cutler Narrows.Bonneville shoreline is lowest white; Provo shoreline is between blue and green shading.White box outlines area in Figure 2.

Figure 2 .
Figure 2. Digital-elevation model of LIDAR data of the Newton Hill area.A western strand of the Dayton-Oxford fault zone intersects the pit (DO).Farther west, several Newton fault scarps are left unlabeled to show their clear topographic expression.B = Bonneville shoreline, P = Provo shoreline.Contour interval 20 m.Blue is lower, brighter colors higher.

7Figure 3 .Figure 4 .
Figure 3. Map of Staker-Parsons gravel pit SE of Newton Hill shows locations of OSL and ISRL age dates; contours of the tops of the extensive red Fielding geosol in the S and W, the pink/white/green shrinking marl in the N and SE, the laminated green clay between them; locations of geologic cross sections A -A' to D -D' in Figure 4, and locations of Figures 6A, B, C and 7A, B.

Figure 5 .
Figure 5. Hydrographs showing changes in shoreline levels in the main Bonneville basin and Cache Valley since 200 ka compared with simultaneous climatic changes.Dates with error bars, ages of ashes and chrons, and sources are from Table1 and Appendices 2 and were revised from Oaks and others (2019).
Figure 5. Hydrographs showing changes in shoreline levels in the main Bonneville basin and Cache Valley since 200 ka compared with simultaneous climatic changes.Dates with error bars, ages of ashes and chrons, and sources are from Table1 and Appendices 2 and were revised from Oaks and others (2019).

Figure 6 .Figure 7 .
Figure 6.A) Original exposure of Cutler Dam (Qcd) gravel overlain by the double Fielding geosols (Qfg), beneath deep-water Bonneville and younger Provo deposits (Qlb).B) Exposures W from the above site showed lateral continuity of this sequence in the hanging wall of the Dayton-Oxford fault.The fault dips toward viewer.Figure C) Details of Qcd, Qfg, and Qlb at sample site USU-856.D) Map showing camera positions of Figures 6A, B, C. Locations shown in Figure 3.

Figure 10 .
Figure 10.Exposure of distinctive marls within Bonneville (Qlb) nearshore gravels in Newton pit.The pink marl is widespread in the Newton Hill pit whereas the underlying laminated green marl is more restricted.Thad Erickson = 1.8 m.NW part of pit.The stratigraphic position and gravel of the slump above the pink marl suggests a possible trigger by the Bonneville flood.The pink marl records the deepest water depths.

Figure 9 .
Figure 9. Schematic cross section of the relative geometries of deposits of three pluvial lakes in Cache Valley, intervening double soils, the modern geosols, and the modern surface soil on the double paleosols above the Bonneville shoreline in eastern Cache Valley and the Newton Hill pit.Qlb = Bonneville lake cycle; Qlbb = Bonneville shoreline; Qlbp = Provo shoreline; Qfg = double Fielding geosols; Qcd = Cutler Dam lake cycle; Qlv = Little Valley lake cycle; MIS = marine oxygen-isotope stage.Although we found no distinct MIS 5 paleosol developed on Qlv, it might be incorporated in the base of Qfg above Qcd deposits.Above the Bonneville shoreline, modern soil is developing on and augmenting exposed Qfg.Horizontal scale is tens of kilometers.Concept fromOviatt and others (1987).Any paleosols within lake cycles are omitted.Altitudes are not corrected for rebound.

Figure 11 .
Figure 11.Geologic cross section showing alternating pluvial fines (blue) and interglacial gravel and sand deposits (orange) beneath the low part of Cache Valley.This section is through College Ward in central Cache Valley, Utah, along U.S. Highways 89/91.Qlb = Bonneville; Qcd? = Cutler Dam; Qlv? = Little Valley.See Figure 1A for location.Question marks indicate that correlations with other lake cycles are possible.Williams (1962) first documented these repeating coarse and fine intervals of lacustrine and fluvial deposits in drill holes in five geologic cross sections across the Utah part of Cache Valley.

Table 1 .
OSL & IRSL sample information and ages for Staker-Parson gravel pit (SE flank of Newton Hill), SE Hyde Park, and NE Millville, Cache County, Utah.See Appendix 1 for details for these samples.