Depositional contacts of loess – Columbia River basalt as analogs for lunar regolith, Martian dust, and impact ejecta lobe breccia matrices:

A field trip during the GSA Regional in Spokane

Field Trip Leaders:

Shawn Wright, Planetary Science Institute

Mark Sweeney, University of South Dakota

Amanda Steckell, University of Colorado Boulder

Sections below

Introduction to fine-grained materials in the solar system, loess, CRB in eastern Washington                                                                                                                         

GSA Regional in Spokane, WA and field trip                                                                      

Proposed Schedule  – Table 1

Comparison of loess to planetary fines – Table 2                                                                                                                                           

Description of field trip                                                                                                      

  Field Trip Stops                                                                                                             

Fine-grained surfaces and settings from a range of processes on the Moon and Mars

Fine particle sizes finer than mud/clay such as is typical for dust and loess make up a significant fraction of the surfaces of the Moon and Mars.  This includes the fines composing the matrix, and not the larger clasts, of impact breccias composing ejecta of several well-preserved terrestrial impact craters such as Meteor Crater and Lonar crater.  These materials, including regolith on the Moon and copious dust on Mars, are not available to the field geologist to examine.  This is because only 12 people have sampled lunar regolith and no one has been to Mars, and there are only perhaps three or four well-preserved ejecta blankets in which the breccia matrix is still available.  We wish to explore the field and laboratory data (as a proxy for rover instruments) of collected samples of these fine-grained materials and share these, but this is difficult.

Here, we introduce a rare very fine-grained deposit on Earth that is accessible to field geologists.  Further, one of its constituents and the lithology underlying it is the very well-known Columbia River basalt (CRB), which has been called an excellent Mars analog (Ruff and Christensen, 2002).  Thus, the field sites of the fine-grained material interacting with, and actually being somewhat composed of, a flood basalt make for a great analog environment for students and professional geologists to think about what past and current Mars rovers and future Artemis astronauts will encounter.  Both of these planetary fines likely were pulverized by volcanic (ashes) and impact cratering (ejecta) processes whereas wind also helped to deposit Martian dust.  All of these – ejecta breccia lobe matrices, lunar regolith, and wind can be examined and discussed at outcrops we suggest below as field trip leader Wright will bring ejecta/ejected samples, and the Cascades provide a volcanic landscape.

Glacial loess in southeastern Washington

This field area was chosen as an analog to the fine-grained planetary surface materials described here due to the variety of particle sizes, but primarily because the finest sizes (~<5-10 microns) are so rare on Earth to be concentrated over a large area.  The Columbia Plateau contains fine-grained particulates and soils (Sweeney et al., 2005,; 2007; McDonald et al., 2012) that we will use as analogs for planetary materials.  The source of the sediments is suggested to be a combination of wind-blown dust from southwesterly winds, andesitic ash from the Cascades, local Columbia River basalt (“CRB”), and metagranitic glacial till from the north (the Canadian Shield). At a few locations (McDonald et al. 2012), the loess is derived from glacial outburst flood sediment and not basalt, but the fractions of each source have only been determined in a few places (Bettis et al., 2003).  More data is needed to see if this is heterogeneous.  Busacca et al. (2001) found that the volcanic glass content of the loess ranges from 6% in the southwest to 27% in the northwest of the plateau, with an average of 12% throughout.  This volcanic glass is attributed to Cascade eruptions.  As the Palouse Hills loess is up to 76 meters thick (Ringe, 1970) overlying Columbia River basalt, there is probably a large range of grain sizes and compositions.

The loess of the Palouse and surrounding areas in the Pacific Northwest discontinuously covers ~50,000 km2 and is >1 Ma based on the presence of normally and reversely magnetized loess (Busacca, 1989), and on the identification of a Kulshan caldera tephra from the northern Cascades dating to ~1.15 Ma, found at 15 m depth in a 26 m outcrop of deep loess near Washtucna (King et al., 2016).

The source of the loess is primarily from wind erosion of Pleistocene glacial outburst megaflood deposits (McDonald et al., 2012). Floods coursed through southeast Washington, scouring sediment and rock to form the Channeled Scabland and depositing sand and silt rich deposits where flood waters slowed and ponded (Baker, 2009). These finer grained sediments served as sources of dust that became loess, supported by geochemical and mineralogical analysis (McDonald et al., 2012).  Prevailing southwesterly winds transported dust from the megaflood source areas; the dust accumulated as loess deposits that tend to thin and become finer grained downwind to the northeast near Spokane, WA (Busacca and McDonald, 1994). The source of eolian sediments were periodically replenished by megaflood events, particularly from floods derived from the catastrophic draining of glacial Lake Missoula (McDonald and Busacca, 1988), dating back ca. 2 Ma (Bjornstad et al., 2001). The loess represents a windy, arid to semi-arid climate that occurred during cold glacial phases, paired with sand dune activity to the upwind near source areas (Sweeney et al., 2017; Gaylord et al., 2001). There are many loess units, with the most recent L1 loess dating from ca. 15 ka to present, underlain by the L2 loess dating from ca. 77 to 15 ka (McDonald et al., 2012). The older loess units dating back to at least 1 Ma are separated by paleosols (Busacca, 1989). Paleosols within loess represent times of relative landscape stability and lower loess accumulation rates, which tended to occur warmer interglacial climates (McDonald and Busacca, 1990). The paleoclimate reconstruction from the loess and paleosols is based on features including ichnofabrics (O’Geen and Busacca, 2001), opal phytolith analysis (Blinnikov et al., 2001), and carbonate clumped isotope thermometry (Lechler et al., 2018) with age control provided by tephrochronology and luminescence dating (summary in Sweeney et al., 2017).

In total, the Palouse loess is up to 76 m thick (Ringe, 1970) and the thickness is considerably variable. The thickest loess tends to occur closest to the dust source areas, as well as in areas where there are several stacked loess units (Busacca and McDonald, 1994). Areas of loess proximal to eolian sand can be sandblasted and thin, whereas loess separated from eolian sand by a topographic barrier such as a canyon, tends to be thick (Sweeney et al., 2005). Loess thickness is also strongly controlled by outburst flooding. Loess within and adjacent to outburst flood channels, or coulees, would have been eroded away. Areas outside the major areas of flooding preserve longer records of loess, as well as loess “islands” shaped by flooding (McDonald and Busacca, 1988). Loess accumulation is facilitated by vegetation cover such as grass and shrubs, which help trap the dust deposited on the surface, protecting it from being re-entrained by the wind. Areas of loess cover were likely always vegetated, albeit with variable vegetation density due to climate conditions (Busacca, 1989; Sweeney et al., 2017), thus why areas of loess facilitate thicker loess accumulations over the long term. Basalt outcrops in the Channeled Scabland, on the other hand, lacked vegetative cover following flood episodes, and therefore lacked traps for dust deposition. Thin dust accumulation within basalt rubble capping outcrops may have eventually provided a soil mantle for plant growth of scattered shrubs and patches of grass cover, eventually enabling thin loess caps, usually < 1 m, on basalt.

Flood sediments contain basalt sand and gravel eroded from the Columbia River Basalt that is pervasive in southeast Washington, mixed with silicate-rich mineral and lithic sediments derived from the Rocky Mountains and other sources. Sand dunes derived from flood sediment, for example, contains quartz, feldspar, mica, heavy minerals, and basalt lithic grains. Comparatively, the Pleistocene buried sand sheet is richer in quartz and feldspar but lacks the basalt lithic grains. Sweeney et al. (2007) suggested that modern and Pleistocene eolian sands were derived from similar megaflood sources, but the Pleistocene eolian sand was transported farther, and in the processes lost the basalt lithic grains to mechanical breakdown during saltation transport. The silt-sized basalt grains were blown farther downwind as dust. The eolian abrasion of basalt sand has been proposed as a source of dust on Earth and Mars (Bristow and Moller, 2018).

   Figure 1.  Contour maps showing the finest loess is near Spokane (Busacca and McDonald 1994).  While the contour lines can be difficult to see, note “10” µm for L1 on the left (map labelled ‘b’) and “14” µm for L2 on the right (map labelled ‘d’) in the upper right corner of both contour maps.  These represent the finest loess and are near Spokane.  The dashed line running across the top of both contour maps is the Spokane River, with the city of Spokane  near the upper right corner of both maps and seen in Figure 2 below.

  Figure 2.  ASTER satellite image of Washington state from Seattle (west) to Spokane (east), showing yellow loess.  Labelled flags represent GPS points and labels from a previous Sweeney field trip, with “WIN-1” Winona described below.  The Spokane River northwest of Spokane correlates to the dashed line described in Figure 1 (upper right corner) and is the northernmost extent, aerially, of the yellow loess.  Whereas the brightest yellow is Palouse loess, the darker areas within represent the “Scablands” where floods stripped away loess and CRB.  The red dot near the ‘S’ in Spokane correlates to white dots ○ in the upper right of Figure 1.

Geological Society of America (GSA) combined regional meeting (Cordilleran, Rocky Mountain sections) in Spokane, Washington May 15-17, 2024

The field trip will feature Sweeney describing the Palouse loess, whereas Wright will briefly discuss the mineralogy of the CRB and the analogous planetary environments we propose (Table 2).  A GSA field trip guidebook will have a table similar to Table 2 here that compares and contrasts, with many references, the particle sizes, mineralogy/sources, and mode of creation/pulverization for the four types of materials.

Table 1.  Schedule

The field trip will have an expert of dust sedimentology (Sweeney) at field stops combined with a mineralogist / spectroscopist Mars scientist (Wright) to discuss dust on Mars, lunar regolith, and the fine matrices of impact breccia.  Sweeney led a field trip for GSA Seattle in 2017 through central and southeastern Washington (email for that guidebook).  Now we will go to the finest of the loess outside and just west of Spokane.

Several discussions will take place during the field trip concerning common planetary instrumental analyses (rover, satellite, and rare cases in the lab) that are used to solve problems on the nature of Martian dust and lunar regolith.  The rarity of well-preserved impact sites on Earth will also come into play as Wright will share samples and discuss the ejecta blankets of Meteor Crater and Lonar crater.  We will extrapolate the larger impact record of Mars and the Moon to ask field trip participants “how many impact-pulverized fines can we estimate for Mars and the Moon?” along with many other thought-provoking questions on the source and mineralogy of fines.

Columbia River basalt (on the field trip) and Deccan basalt (from Lonar crater, India) are both excellent analogs for Mars basalt with ~45% andesine or labradorite combined with 30-35% clinopyroxenes augite and pigeonite.  The provenance or source of the loess will be discussed, as previous workers know it is “some combination” of CRB, Cascades silicic ash, global airborne dust, and glacial flour from the Canadian Shield (metagranites).  We suggest that at least one discussion on the field trip will focus on HOW to solve this from rover, satellite, drone, or sample return / laboratory instruments from geochemical, mineralogical, and perhaps other analyses. 

This field trip should be of interest to those expecting to study fines in planetary environments.  These science communities include, but are not limited to: those interested in upcoming regolith collection on the Moon by astronauts, those examining Martian dust, lunar meteorites/samples/impact history, lunar remote sensing of impact sites and regional geology; studies of Mars through remote, rover, and meteorite/basalt data; laboratory analyses of high-resolution remote sensing of asteroids and planetesimals, and even HiRISE of Mars, as some images are so high resolution (e.g., 30 cm for HiRISE) that they proxy as field images.

The field trip leaders considered having a half-day workshop in the morning before the field trip or day before.  However, there will be a “workshop-style” format for our field trip.  We decided that the field is better than a conference room to discuss ideas.  The field will be our “classroom” or meeting place as we will discuss what is known about Martian dust, lunar regolith fines, and the fines of impact ejecta breccia lobes.  Wright will bring solid (in epoxy) samples of impact breccia in which the fines of the matrix can be seen, along with photomicrographs and spectroscopy of these fines.  Wright and Sweeney will also ask beforehand if anyone has any literature or questions to ask about fines on planetary surfaces.  In this, the field trip participants can choose to present material and/or we can all discuss possible answers to their questions about Martian dust, lunar fines, etc. 

Goals of the Field Trip

The goals of the 1-day workshop/field trip are: 1) create investigator networks through the open exchange of ideas, 2) introduce current or future or potential investigators to new subject areas or research techniques, 3) provide scientific/technical training (field work, with the field guide containing instrument analyses) for investigators, and 4) encourage the use of (NASA) mission data.  Goals #1, #2, and #3 will be accomplished directly during the field trip, and we envision that field trip participants will learn new concepts concerning laboratory and field data of fine-grained loess and basalt that can be applied to goal #4.  This is augmented by the diversity of attendance of several science communities who regularly attend GSA and often have questions for the terrestrial impact community (Wright) and loess expert (Sweeney, others) concerning both field and sample/laboratory data as it pertains to their own sample or remote research.  These science communities include, but are not limited to: those interested in upcoming regolith collection on the Moon by astronauts, those examining Martian dust remotely or with rover data, lunar meteorites/samples/impact history [i.e., Cavosie et al., 2015], lunar remote sensing of impact sites and regional geology; studies of Mars through remote, rover, and meteorite/basalt data; laboratory analyses of high-resolution remote sensing of asteroids and planetesimals, and even HiRISE of Mars, as some images are so high resolution (e.g., 30 cm for HiRISE) that they proxy as field images.

A preliminary draft of a field guide has been written; an example Table 2 and four stops are summarized below.  

Description of the Field Trip Stops

We describe the field stops below starting with the first stop, then we describe the last stop, and then a few of 4-5 stops we plan to be in-between.  The first stop focuses on loess, intermediate stops show both loess and CRB, and the last stop we describe is an easy-to-get-to local park that will probably conclude the field trip (if time).  A feature only possible with loess (“bleeding”/staining) is described as well.  Lastly, we describe but don’t show figures of a typical depositional setting that most have seen – the sprinkling of loess and thus in a checkerboard mixing scenario with underlying basalt.  Thus, there are three types of contacts (stacks, sprinkling, and rare staining) with the first stop being a well-studied loess exposure.  The name of the stop describes the focus of that stop below.

Table 2.  This table represents a very small example of a large table that will be in the GSA field guide.  The final table will have several dozen references on Palouse loess, lunar regolith studies, Martian dust remote and rover studies, and 5-10 references on Lonar crater, India ejecta along with the other few terrestrial impact sites that still have well-preserved matrices in the suevite and/or lithic breccia (though not basalt like Lonar).  In this, the final field guide will be a great reference for planetary scientists to delve into studies of fine-grained materials.  There will be more columns such as “samples” (several Lonar impactites and at least one lunar regolith breccia NWA 5000 will be passed around during the field trip) and perhaps a very specific “composition” column will list the mineralogy and references for CRB, Deccan basalt, lunar basalt and anorthosite (that make up the fines of regolith; Qian et al. 2020) and a long list of compositional studies done for the Palouse loess (e.g., Busacca et al. 2001; McDonald et al. 2012).

First Stop:  Thick accumulations of loess at Winona

On a previous GSA field trip led by Sweeney, field trip participants explored this outcrop (Sweeney et al. 2017).  Whereas there are larger exposures of several defined sections of the Palouse loess to the south and farther west (Sweeney et al. 2017), the Winona outcrop is the largest exposure of a thick sequence of loess that is the closest to Spokane (80-minute drive).  The stop is shown as WIN-1 on Figure 2.

The Winona outcrop represents distal loess accumulation in a higher-elevation setting (520 m) with a MAP of 400 mm, located ~65 km downwind of Eureka Flat (Fig. 2).  Many of the paleosols and features are pedogenically welded, or superimposed, due to the thinner nature of the loess units here (L1 is 1.2 m thick, L2 is 1.4 m thick).  Winona is dominated by either cylindrical cicada burrows or earthworm fabric (King, 2000) and was first described in 1985 (McDonald, 1988).  Over 20 m of loess is exposed here and it is all normally magnetized (Busacca, 1989). Even though the loess units are thinner, this site has a long history, containing at least 20 calcic paleosols likely extending back several hundred thousand yr.  At ~1.3 m depth, the Trego Hot Springs tephra (26 ka calibrated; King et al., 2016) mixed with the Mount St Helens (MSH) set S tephra was identified. The Mount St. Helens set C tephra is located at the base of L2 loess, and luminescence ages straddling the L2-L3 loess boundary are 53–58 ka (Richardson et al., 1997). A glacial outburst megaflood-cut unconformity was described below the Devils Canyon Soil, providing additional evidence for pre-late Wisconsin floods (McDonald and Busacca, 1992).  A ca. 100 ka tephra correlated to Carp Lake (Whitlock et al., 2000) was found at a depth of 6 m at this outcrop, and a luminescence age below the tephra came back 99.6 ka (Richardson et al., 1997). The oldest luminescence age (116 ka) from this outcrop was measured at ~8 m depth (Richardson et al., 1997). 

   Figure 3. Field photo of the upper part of the Winona outcrop showing the relatively thin, buried soils at this distal loess locality. Several of the buried soils are welded, with features of one soil overprinting the other.  The contact and loess layers L1 and L2 are described above and in Sweeney et al. (2017). 

Despite being in a distal location, the grain size fluctuates significantly, likely influenced by eolian input from megaflood coulees located nearby. Local sources of sediment contributed to the accumulation of loess at this location, along with dust from distal sources such as Eureka Flat.

Magnetic susceptibility was also measured here, and the results are similar to other outcrops to the south (King, 2000).  The signature in the upper 5 m of loess follows grain size changes. Below 5 m, the signature no longer follows changes in grain size, but nevertheless has a signature similar in magnitude to slackwater sediments. The magnetic susceptibility signature of the entire outcrop appears to be influenced by a detrital component, rather than by pedogenesis.

The Winona field site is an excellent stop to show field trip participants as “typical” of a loess outcrop as they will see near Spokane, and represents the larger deposit throughout the Palouse.  We will spend some time here for Sweeney to describe the Palouse loess as a whole along with the grain sizes found throughout the Palouse and near Spokane (Figures 1, 2, and 3).

Last Stop: Loess exposures and other sedimentary features in Campion Park in Spokane

   Figure 4.  Campion Park in Spokane shows ~1.5 m of loess (background on left) that is located at the bottom/south end of the GoogleEarth view on right.  Left: Glacial erratics such as CRB and granite make up the cobbles and pebbles in the intermittent stream (foreground on right).  Right/GoogleEarth: There are large ~40-50 m cliffs vertically below the neighborhood houses that are above the cliff (i.e., west of the stream is ~40-50 meters lower elevation than east of the stream); these can be seen from Campion Park but not explored.  

This stop in Spokane (Figure 4) has 1-2 meters of loess and is conveniently located in Spokane.  This may be our last stop, timewise, and thus optional for those who have rental cars or can Uber to Campion Park.  The field guide will describe much more than seen in the figure below so field guide readers can visit this stop if there is not enough time on May 14^th.  The writeup will be more of a “walking guide” for locals as well.  There is loess to sample and discuss along with glacial erratics and local bedrock found in the stream.  Whereas these cobbles are not the focus of this field trip, they allow for us to see CRB and granite downstream and rounded in a fluvial setting.  Further, tall “stacks” of loess to east of channel (below elevated housing development), are not accessible but can be viewed from Campion Park.

Stop: Loess “bleeding” into underlying CRB

This stop near Turnbull National Wildlife Refuge is a 35-minute drive from Spokane.  These stops show a very interesting type of depositional contact that we suggest will be of great interest to geologists studying Mars and impact ejecta (Figure 5).  In this proposal, we briefly differentiate here between a coating and a rind.  A coating is extraneous material (e.g., fines or clay or MnO2) that coats the outside of a rock surface or preexisting lithologic surface.  A rind is an alteration material that develops within the rock and generally towards the outside of said rock.  But here at this field trip stop (Figure 5), we will show a rare occurrence of a coating that has penetrated deeper within the underlying lithology.  Both (the coating of loess and the underlying basalt) are of interest for the goals of this field trip.  We are not trying to suggest that this is a “completely new concept never seen before,” but it is rare, as most depositional contacts are either a stack of loess (e.g., Winona field stop Figure 3 or Campion Park Figure 4) or the two lithologies exist in checkerboard mixing with loess sprinkled on basalt (other field stops described below).  Here, because the loess is so much finer (~1-5 microns per particle) than the matrix and rare phenocrysts of andesine and augite in the CRB (~30-40 microns), the finest loess has migrated into the basalt.  Thus, this acts like a coating, which it is, but also like a rind in that this coating penetrates deeper-than-the-average-coating.  Only loess is small enough to do so.  For example, silt and sand cannot physically go into a basalt.  This makes it rare and interesting as an analog for planetary surfaces that have fines.

We suggest this should be of interest to those studying “dusty” Martian landscapes where this may be possible, along with those examining pristine ejecta clasts that have fine ejecta matrix “bleeding” into the clasts.  We will ask the field trip participants (rhetorically / colloquially) but also seriously “what PhD student wants to collect samples of these and then compare the data (spectra/geochem/mineralogy, etc.) to regular CRB and regular loess?”  We expect to get a few volunteers for this study, but it is up to them to take samples back to their university laboratories.

B.                                                                   

Figure 5.  Loess “bleeding into” and staining underlying CRB.  Both outcrops from road to top is ~1.3 meters.  (A) above:  The loess has completely invaded and stained the underlying CRB, which generally is the dark gray color on the right of outcrop in (B).  (B) to right: A little less staining of the loess into CRB on the left as compared to (A), but still stained.

Several Stops:  Loess “sprinkled” on CRB

There are several stops we will make near Medical Lake and Cheney, WA that show loess and CRB lithologies in a “checkerboard” mixing fashion rather than the typical layered depositional setting.  Spokane Lane State Park north of Spokane also has this type of contact.  These are all on BLM land and field trip participants can collect basalt samples.

Field Trip Leaders:

Shawn Wright has conducted field work at Lonar crater, India for months and was the Field Team Lead for SSERVI TREX that examined fine-grained materials.  A portion of this proposed field trip will be a discussion of the rover/field instrument data and subsequent laboratory “ground truth” data of fines derived from the TREX fieldwork (Steckel et al., 2023; Hendrix 2018).  Wright led field trips to Meteor Crater for three U.S. universities.  Wright led several field trips to the Santa Fe impact structure, New Mexico for courses for five U.S. universities and for MetSoc in 2010 and 2017 and a GSA regional in 2012 (Wright et al., 2010; Wright and Cavosie, 2017). 

Mark Sweeney is a professor in the Department of Sustainability and the Environment at the University of South Dakota.  He is an expert of dust and landscape change.  He has led several field trips for GSA and other organizations to the Palouse loess, including a well-attended, ~20-person field trip for the 2017 GSA Annual Meeting in Seattle.  That field trip and outcrops focused on large “stacks” of loess to the far south (Walla Walla) and west of Spokane, but this field trip will focus on the finest loess naturally available (McDonald and Busacca, 2003) that is in the Spokane region. Sweeney is also conducting research on eolian abrasion of basalt sand as a source of dust as an analog to Mars. One of his field sites is the Moses Lake basaltic dunes near Moses Lake, Washington.

Amanda Steckel is a PhD student working for planetary scientists TREX PI Amanda Hendrix (Planetary Science Institute) and Brian Hynek (faculty at University of Colorado, Boulder).  She compiled a mineral survey with a PIKA IR hyperspectral imager to assist the TREX team in Yellowcat Utah in 2022.  She also joined a field campaign at Ojos del Salado to investigate suitability of arid, high altitude, environments on life, contributing spectroscopy and XRD analysis.

References

Baker, V.R., 2009. The Channeled Scabland: A retrospective. Annu. Rev. Earth Planet. Sci. 37, 393-411.

Bettis III, E. A., Muhs, D. R., Roberts, H. M., & Wintle, A. G. (2003). Last glacial loess in the conterminous USA. Quaternary Science Reviews, 22(18-19), 1907-1946.

Bjornstad, B.N., Fecht, K.R., Pluhar, C.J., 2001. Long history of pre-Wisconsin, Ice Age cataclysmic floods: evidence from southeastern Washington state. J. Geol. 109, 695-713.

Blinnikov, M., Busacca, A., and Whitlock, C., 2001, A new 100,000-year phytolith record from the Columbia Basin, Washington, U.S.A., in Meunier, J. D., and Colin, F., eds., Phytoliths: Applications in Earth Sciences and Human History: Lisse, Balkema, p. 27-55.

Busacca, A.J., 1989. Long Quaternary record in eastern Washington, U.S.A., interpreted from multiple buried paleosols in loess. Geoderma 45, 105-122.

Busacca, A.J., McDonald, E.V., 1994. Regional sedimentation of late Quaternary loess on the Columbia Plateau: sediment source areas and loess distribution patterns. Washington Division of Geology and Earth Resources Bulletin 80, 181-190.

Busacca, A.J., Marks, H.M., and Rossi, R., 2001. Volcanic glass in soils of the Columbia Plateau, Pacific Northwest, USA. Soil Science Society of America Journal v. 65, 161-168.

Bristow, C.S. and Moller, T.H., 2018, Dust production by abrasion of eolian basalt sands: Analogue for Martian dust. Journal of Geophysical Research: Planets v. 123, p. 2713-2731.

Cavosie, A.J., Erickson, T.M., Timms, N.E., Reddy, S.M., Talavera, C., Montalvo, S.D., Pincus, M.R., Gibbon, R., and Moser, D. (2015) A terrestrial perspective on using ex situ shocked zircons to date lunar impacts. Geology, v. 43 (11), p. 999-1002.

Gaylord, D.R., Foit, F.F., Jr., Schatz, J.K., Coleman, A. J., 2001. Smith Canyon dune field, Washington, U.S.A.: relation to glacial outburst floods, the Mazama eruption, and Holocene paleoclimate. J. Arid Environ. 47, 403-424.

Hendrix, A. (2018). Highlights of Science and Exploration Activities at the SSERVI TREX Node. 42nd COSPAR Scientific Assembly, 42, B3-1.

Hosterman, J.W. (2013) Geology of the clay deposits in parts of Washington and Idaho, Proceedings of the Seventh National Conference on Clays and Clay Minerals, pages 285-292, doi: 10.1016/B978-0-08-009235-5.50022-X

Johnson, J. R., Grundy, W. M., & Lemmon, M. T. (2003). Dust deposition at the Mars Pathfinder landing site: Observations and modeling of visible/near-infrared spectra. Icarus, 163(2), 330-346.

Jourdan, F., Moynier, F., Koeberl, C. and Eroglu, S., 2011. 40Ar/39Ar age of the Lonar crater and consequence for the geochronology of planetary impacts. Geology, 39(7), pp.671-674.

King, G.E., Pearce, N.J.G., Roberts, H.M., Smith, V.C., Westgate, J.A., Gaylord, D.R., Sweeney, M.R., 2016. Identification of a Kulshan caldera correlative tephra in the Palouse loess of Washington State, northwest, USA. Quat. Res. 86, 232-241.

Lechler, A.R., Huntington, K.W., Breecker, D.O., Sweeney, M.R., Schauer, A.J., 2018. Loess-paleosol carbonate clumped isotope record of late Pleistocene-Holocene climate change in the Palouse region, Washington State, USA. Quaternary Research 90, p. 331-347.

Maloof, A.C., Stewart, S.T., Weiss, B.P., Soule, S.A., Swanson-Hysell, N.L., Louzada, K.L., Garrick-Bethell, I. and Poussart, P.M., 2010. Geology of Lonar crater, India. Bulletin, 122(1-2), pp.109-126.

McDonald, E.V., Busacca, A.J., 1988. Record of pre-late Wisconsin giant floods in the Channeled Scabland interpreted from loess deposits. Geology 16, 728–731.

McDonald, E.V. and Busacca, A.J., 1990, Interaction between aggrading geomorphic surfaces and the formation of a Late Pleistocene paleosol in the Palouse loess of eastern Washington state, Geomorphology, vol. 3, p. 449-470.

McDonald, E.V., Sweeney, M.R., and Busacca, A.J., 2012, Glacial outburst floods and loess sedimentation documented during Oxygen Isotope State 4 on the Columbia Plateau, Washington State, Quaternary Science Reviews, v. 45, p. 18-30, doi:10.1016/j.quascirev.2012.03.016.

O’Geen, A.T., Busacca, A.J., 2001. Faunal burrows as indicators of paleo-vegetation in eastern Washington, USA.Palaeogeogr. Palaeoclimatol. Palaeoecol. 169, 23-37.

Qian, Y et al. 2020) The regolith properties of the Chang’e-5 landing region and the ground drilling experiments using lunar regolith simulants, Icarus, doi: 10.1016/j.icarus.2019.113508

Ringe, D., 1970, Sub-loess basalt topography in the Palouse hills, southeastern Washington: Geological Society of America Bulletin, v. 81, p. 3049-3060.

Ruff, S. W., & Christensen, P. R. (2002). Bright and dark regions on Mars: Particle size and mineralogical characteristics based on Thermal Emission Spectrometer data. Journal of Geophysical Research: Planets, 107(E12).

Steckel, A.V. et al. (2023) Utilizing a hyperspectral camera for field surveys during the TREX field mission, LPSC 2023, abstract #2720.

Sweeney, M.R., Busacca, A.J., and Gaylord, D.R., 2005. Topographic and climatic influences on accelerated loess accumulation since the last glacial maximum in the Palouse, Pacific Northwest, USA. Quat. Res. 63, 261-273.

Sweeney, M.R., Gaylord, D.R., Busacca, A.J., 2007. The evolution of Eureka Flat: A dust producing engine of the Palouse loess, USA. Quat. Internat. 162-163, 76-96.

Sweeney, M.R., McDonald, E.V., and Gaylord, D.R., 2017, Generation of the Palouse loess:   Exploring the linkages between glaciation, outburst megafloods, and eolian deposition in Washington State, in Haugerud, R.A., and Kelsey, H.M., eds., From the Puget Lowland to East of the Cascade Range: Geologic Excursions in the Pacific Northwest: Geological Society of America Field Guide 49, p. 207-228.

Wright S. P., Cavosie A. J. (2017) Shatter cones and breccias of the Santa Fe impact structure, in: Recognizing Criteria for Ancient Impacts: A Workshop and Field Guide for the Santa Fe Impact Structure. S. P. Wright and A. J. Cavosie (organizers). 80th Annual Meeting of the Meteoritical Society. 28 pp. https://www.impactcraters.us/fieldguideSF2017.pdf

Wright, S.P. and J.R. Michalski (2024) Shocked soil – a rare terrestrial impactite, JGR-Planets, doi: 10.1029/2023JE007913.

Wright, S.P., E.L. Tegtmeier, and H.E. Newsom (2010), Diversity of breccias associated with the Santa Fe impact structure, Lun. Plan. Sci. Conf. XLI, #1286, The Woodlands, TX.