USGS Geoscience Data Catalog
Additional USGS Geoscience data can be found by geographic location or by publication series.
Reheis, Marith C., Goodmacher, Johnathan C., Harden, Jennifer W., McFadden, Leslie D., Rockwell, Thomas K., Shroba, Ralph R., Sowers, Janet M., and Taylor, Emily M., 1995, Quaternary Soils and Dust Deposition in Southern Nevada and California: Geological Society of America Bulletin volume 107, Geological Society of America, Kansas.Online Links:
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.01. Longitudes are given to the nearest 0.01. Latitude and longitude values are specified in Decimal degrees.
Column 1 Area Column 2 Dust Trap Column 3 surface (no. for ave.) Column 4 Age, Best Column 5 Age, Min Column 6 Age, Max Column 7 Prof. Mass, Silt, (g/cm2/soil col.) Silt Column 8 Prof. Mass, Clay, (g/cm2/soil col.) Clay Column 9 Prof. Mass, CaCO3, (g/cm2/soil col.) CaCO3 Column 10 Prof. Mass, Salt, (g/cm2/soil col.) Salt Column 11 Silt, Best Column 12 Silt, Max Column 13 Silt, Min Column 14 Clay, Best Column 15 Clay, Max Column 16 Clay, Min Column 17 CaCO3, Best Column 18 CaCO3, Max Column 19 CaCO3, Min Column 20 Salt, Best Column 21 Salt, Max Column 22 Salt, MinCore/meta/dsindrpn.txt
Column 1 Sample number Column 2 Horizon Column 3 Thickness, (cm) Column 4 Rubification, Norm. value Column 5 Rubification, Horizon value Column 6 Rubification, Profile value Column 7 Melanization, Norm. value Column 8 Melanization, Horizon value Column 9 Melanization, Profile value Column 10 Paling, Norm. value Column 11 Paling, Horizon value Column 12 Paling, Profile value Column 13 Lightening, Norm. value Column 14 Lightening, Horizon value Column 15 Lightening, Profile value Column 16 Total, Texture Norm. value Column 17 Total, Texture Horizon value Column 18 Total, Texture Profile value Column 19 Structure, Norm. value Column 20 Structure, Horizon value Column 21 Structure, Profile value Column 22 Dry Consistence, Norm. value Column 23 Dry Consistence, Horizon value Column 24 Dry Consistence, Profile value Column 25 Clay Films, Norm. value Column 26 Clay Films, Horizon value Column 27 Clay Films, Profile value Column 28 Carbonate, Norm. value Column 29 Carbonate, Horizon value Column 30 Carbonate, Profile value Column 31 pH decrease, Norm. value Column 32 pH decrease, Horizon value Column 33 pH decrease, Profile value Column 34 pH increase, Norm. value Column 35 pH increase, Horizon value Column 36 pH increase, Profile value Column 37 Profile Index 1, Norm. value (rb, ml, tx, st, dc, cf, pHde) Column 38 Profile Index 1, Horizon value (rb, ml, tx, st, dc, cf, pHde) Column 39 Profile Index 1, Profile value (rb, ml, tx, st, dc, cf, pHde) Column 40 Profile Index 2, Norm. value (pl, lt, tx, st, dc, cf, pHin) Column 41 Profile Index 2, Horizon value (pl, lt, tx, st, dc, cf, pHin) Column 42 Profile Index 2, Profile value (pl, lt, tx, st, dc, cf, pHin) Column 43 Profile Index 3, Norm. value (pl, lt, tx, st, dc, cf, pHin) Column 44 Profile Index 3, Horizon value (pl, lt, tx, st, dc, cf, pHin) Column 45 Profile Index 3, Profile value (pl, lt, tx, st, dc, cf, pHin)Core/meta/dsolab.txt
Column 1 Sample number Column 2 Profile number Column 3 Horizon name Column 4 Depth to base (cm) Column 5 Gravel content, Est. vol.% Column 6 Gravel content, Weight% Column 7 pH Column 8 Weight percent of less-than-2mm fraction O.M. Column 9 Weight percent of less-than-2mm fraction Sand Column 10 Weight percent of less-than-2mm fraction Silt@ Column 11 Weight percent of less-than-2mm fraction Clay Column 12 Weight percent of less-than-2mm fraction CaCO3* Column 13 Weight percent of less-than-2mm fraction Salt**Core/meta/dsoldes.txt
Column 1 Surface / Elevation (m)/ age Column 2 Profile / Describer(s) Column 3 Sample / Number Column 4 Horizon Column 5 Boundary Depth (cm) top Column 6 Boundary Depth (cm) base Column 7 Boundary nature Column 8 Matrix Color #1, Dry Column 9 Matrix Color #1, Moist Column 10 Carbonate Color #2, Dry Column 11 Carbonate Color #3, Dry Column 12 Carbonate Color #4, Dry Column 13 Texture Column 14 Structure, Primary Column 15 Structure, Secondary Column 16 Consistence, Dry Column 17 Consistence, Wet Column 18 Clay films, Primary Column 19 Clay films, Secondary Column 20 CaCO3 Matrix Column 21 CaCO3 Gravel Column 22 % gravel <2 mm Column 23 Parent material and lithology Column 24 Roots Column 25 Pores Column 26 SiO2 Column 27 Salt Column 28 Miscellaneous notesCore/meta/dsolloc.txt
Column 1 Soil-study site(&) Column 2 Source of soil data (@) Column 3 Parent material type* Column 4 Parent material lithology Column 5 Trap (T-) Column 6 Trap latitude Column 7 Trap longitude Column 8 Trap elevation Column 9 est. (+) MAT (±1.3C) Column 10 est. (+) MAP (cm)Core/meta/dsolmin.txt
Column 1 Area Column 2 Profile Column 3 Best age (ka) Column 4 Horizon Column 5 Chlorite Column 6 Kaolinite Column 7 Mica Column 8 Vermiculite Column 9 Smectite Column 10 Mixed-layer Column 11 Palygorskite Column 12 QuartzCore/meta/dsolox.txt
Column 1 Profile no. Column 2 Horizon Column 3 Percent SiO2 Column 4 Percent Al2O3 Column 5 Percent Fe2O3 Column 6 Percent FeO Column 7 Percent MgO Column 8 Percent CaO Column 9 Percent Na2O Column 10 Percent K2O Column 11 Percent TiO2 Column 12 Percent P2O5 Column 13 Percent MnO Column 14 Percent ZrO2 Column 15 factor Column 16 Percent oxides recalculated to 100%, SiO2 Column 17 Percent oxides recalculated to 100%, Al2O3 Column 18 Percent oxides recalculated to 100%, Fe2O3 Column 19 Percent oxides recalculated to 100%, FeO Column 20 Percent oxides recalculated to 100%, MgO Column 21 Percent oxides recalculated to 100%, CaO Column 22 Percent oxides recalculated to 100%, Na2O Column 23 Percent oxides recalculated to 100%, K2O Column 24 Percent oxides recalculated to 100%, TiO2 Column 25 Percent oxides recalculated to 100%, P2O5 Column 26 Percent oxides recalculated to 100%, MnO Column 27 Percent oxides recalculated to 100%, ZrO2 Column 28 Percent CaCO3 Column 29 Percent CaO in CaCO3 Column 30 iterations factor 1 Column 31 factor 2 Column 32 Percent recalculated with CaO due to CaCO3 removed, SiO2 Column 33 Percent recalculated with CaO due to CaCO3 removed, Al2O3 Column 34 Percent recalculated with CaO due to CaCO3 removed, Fe2O3 Column 35 Percent recalculated with CaO due to CaCO3 removed, FeO Column 36 Percent recalculated with CaO due to CaCO3 removed, MgO Column 37 Percent recalculated with CaO due to CaCO3 removed, CaO Column 38 Percent recalculated with CaO due to CaCO3 removed, Na2O Column 39 Percent recalculated with CaO due to CaCO3 removed, K2O Column 40 Percent recalculated with CaO due to CaCO3 removed, TiO2 Column 41 Percent recalculated with CaO due to CaCO3 removed, P2O5 Column 42 Percent recalculated with CaO due to CaCO3 removed, MnO Column 43 Percent recalculated with CaO due to CaCO3 removed, ZrO2 Column 44 SumCore/meta/dsolpw.txt
Column 1 Sample number Column 2 Profile number Column 3 Horizon name Column 4 Thickness (cm.) Column 5 Gravel content vol.% Column 6 Gravel content wt.% Column 7 Organic matter Column 8 Silt content of less-than-2mm fraction (weight %) lab Column 9 Silt content of less-than-2mm fraction (weight %) PM Column 10 Clay content of less-than-2mm fraction (weight %) lab Column 11 Clay content of less-than-2mm fraction (weight %) PM Column 12 CaCO3 content of less-than-2mm fraction (weight %) lab Column 13 CaCO3 content of less-than-2mm fraction (weight %) P.M Column 14 Salt content of less-than-2mm fraction (weight %) lab Column 15 Salt content of less-than-2mm fraction (weight %) P.M. Column 16 Assigned mineral B.D., min Column 17 Assigned mineral B.D., max Column 18 Calculated B.D. of soil, min Column 19 Calculated B.D. of soil, max Column 20 Calculated < 2mm B.D., min Column 21 Calculated < 2mm B.D., max Column 22 Change from parent material, (weight percent) silt Column 23 Change from parent material, (weight percent) clay Column 24 Change from parent material, (weight percent) CaCO3 Column 25 Change from parent material, (weight percent) salt Column 26 Pedogenic silt, Horizon, min Column 27 Pedogenic silt, Horizon, max Column 28 Pedogenic silt, Profile sum, min Column 29 Pedogenic silt, Profile sum, max Column 30 Pedogenic clay, Horizon, min Column 31 Pedogenic clay, Horizon, max Column 32 Pedogenic clay, Profile sum, min Column 33 Pedogenic clay, Profile sum, max Column 34 Pedogenic CaCO3, Horizon, min Column 35 Pedogenic CaCO3, Horizon, max Column 36 Pedogenic CaCO3, Profile sum, min Column 37 Pedogenic CaCO3, Profile sum, max Column 38 Pedogenic salt, Horizon, min Column 39 Pedogenic salt, Horizon, max Column 40 Pedogenic salt, Profile sum, min Column 41 Pedogenic salt, Profile sum, maxCore/meta/intrate.txt
Column 1 soils Column 2 trap Column 3 Assigned age, best Column 4 Assigned age, min Column 5 Assigned age, max Column 6 Interval age, best Column 7 Interval age, min Column 8 Interval age, max Column 9 Silt mass, (g/cm2/col), total Column 10 Silt mass, (g/cm2/col), interval Column 11 Silt interval rate,(g/m2/yr), best Column 12 Silt interval rate,(g/m2/yr), max Column 13 Silt interval rate, (g/m2/yr), min Column 14 Clay mass, (g/cm2/col), total Column 15 Clay mass, (g/cm2/col), interval Column 16 Clay interval rate, (g/m2/yr), best Column 17 Clay interval rate, (g/m2/yr), max Column 18 Clay interval rate, (g/m2/yr), min Column 19 CaCO3 mass, (g/cm2/col), total Column 20 CaCO3 mass, (g/cm2/col), interval Column 21 CaCO3 interval rate, (g/m2/yr), best Column 22 CaCO3 interval rate, (g/m2/yr), max Column 23 CaCO3 interval rate, (g/m2/yr), min Column 24 Salt mass, (g/cm2/col), total Column 25 Salt mass, (g/cm2/col), interval Column 26 Salt interval rate, (g/m2/yr), best Column 27 Salt interval rate, (g/m2/yr), max Column 28 Salt interval rate, (g/m2/yr), minCore/meta/intrtdev.txt
Column 1 soils Column 2 best age Column 3 int. age Column 4 Silt mass, (g/cm2/col), total Column 5 Silt mass, (g/cm2/col), interval Column 6 Silt interval rate, (g/m2/yr), rate Column 7 Silt interval rate, s.d. Column 8 Clay mass, (g/cm2/col), total Column 9 Clay mass, (g/cm2/col), interval Column 10 Clay interval rate, (g/m2/yr), rate Column 11 Clay interval rate, s.d. Column 12 CaCO3 mass, (g/cm2/col), total Column 13 CaCO3 mass, (g/cm2/col), interval Column 14 CaCO3 interval rate, (g/m2/yr), rate Column 15 CaCO3 interval rate, s.d. Column 16 Salt mass, (g/cm2/col), total Column 17 Salt mass, (g/cm2/col), interval Column 18 Salt interval rate, (g/m2/yr), rate Column 19 Salt interval rate, s.d.
303-236-1270 (voice)
<mreheis@gdsvr1.cr.usgs.gov>
The presence of eolian dust in soils and the relative contribution of dust to soil formation in both arid and humid areas has been debated for decades. Most researchers now agree that dust is a ubiquitous component of soils formed in arid areas, although some argue that calcareous dust does not contribute significantly to the content of pedogenic calcium carbonate in some localities. Detailed studies of dust influx facilitate studies of paleoclimate based on modelling of soil-forming processes such as translocation of pedogenic carbonate. Most research on the eolian component of soils has focused on identifying the presence of dust and estimating its proportion relative to soil parent materials and in-situ weathering products. Despite general agreement on the importance of dust to soil genesis, few studies have compared modern rates of dust deposition to estimated amounts of dust in soils of known age to compare the compositions and deposition rates of modern dust to dust in soils. Quantitative comparisons are important to studies of soil genesis, paleoclimatic reconstruction from soil properties, and soil chronosequences used to estimate the ages of surfaces and deposits. For example, soils that formed downwind of a large dust source may be significantly better developed than soils of the same age that formed in sheltered areas. A project to study modern dust deposition in southern Nevada and California was initiated in 1984 to provide data on modern dust composition and influx rates for use in a numerical model relating soil carbonate to paleoclimate and in soil-chronosequence studies in the southern Great Basin and Mojave Desert (fig. 1) in support of tectonic and stratigraphic investigations for the Yucca Mountain Project. In this paper, we relate the composition of modern dust to soil properties and compare modern rates of dust influx with late Pleistocene and Holocene rates estimated from soils at 24 sites in southern Nevada and California.
Amundson, R.G., Chadwick, O.A., Sowers, J.M., and Doner, H.E., 1989, Soil evolution along an altitudinal transect in the eastern Mojave Desert of Nevada, U.S.A.: Geoderma, v. 43, p.: Geoderma volume 43, Elsevier, Amsterdam, New York.
Goodmacher, J., and Rockwell, T., 1990, Properties and inferred ages of soils developed in alluvial deposits in the southwestern Coyote Mountains, Imperial County, California, in Rockwell, T. R., ed., Friends of the Pleistocene, Winter Fieldtrip-1990, Western Salton Trough Soils and Neotectonics: San Diego, California: Privately Published, California, USA.
Harden, J.W., and Matti, J.C., 1989, Holocene and late Pleistocene slip rates on the San Andreas fault in Yucaipa, California, using displaced alluvial-fan deposits and soil chronology: Geological Society of America Bulletin volume 101, Geological Society of America, Kansas.
Harden, J.W., Slate, J.L., Lamothe, P., Chadwick, O.A., Pendall, E.G., and Gillespie, A.M., 1991, Soil formation on the Trail Canyon alluvial fan: U.S. Geological Survey Open-File Report volume 91-291, United States Geological Survey, Denver, Colorado.
Harden, J.W., Taylor, E.M., Hill, C., Mark, R.K., McFadden, L.D., Reheis, M.C., Sowers, J.M., and Wells, S.G., 1991, Rates of soil development from four soil chronosequences in the southern Great Basin: Quaternary Research volume 35.
McFadden, L.D., 1982, The impacts of temporal and spatial climatic changes on alluvial soils genesis in southern California: University of Arizona (Ph.D. dissertation), Tucson, Arizona.
McFadden, L.D., Wells, S.G., and Dohrenwend, J.C., 1986, Influences of Quaternary climatic changes on processes of soil development on desert loess deposits of the Cima volcanic field, California: Catena Volume 13.
Reheis, M.C., Harden, J.W., McFadden, L.D., and Shroba, R.R., 1989, Development rates of late Quaternary soils, Silver Lake playa, California: Soil Science Society of America Journal volume 53.
Reheis, M.C., Sowers, J.M., Taylor, E.M., McFadden, L.D., and Harden, J.W., 1992, Morphology and genesis of carbonate soils on the Kyle Canyon fan, Nevada, U.S.A: Geoderma volume 52.
Sowers, J.M., Amundson, R.G., Chadwick, O.A., Harden, J.W., Jull, A.J.T., Ku, T.L., McFadden, L.D., Reheis, M.C., and Szabo, B., 1988, Geomorphology and pedology on the Kyle Canyon alluvial fan, southern Nevada, in Weide, D.L., and Faber, M.L., eds., This Extended Land: Geological Society of America Guidebook Cordillerian Section Meeting.
Taylor, E.M., 1986, Impact of time and climate on Quaternary soils in the Yucca Mountain area of the Nevada Test Site: Master's thesis, University of Colorado, Boulder Colorado.
Age determination of studied soils.
The ages of the soils sampled for this study (11H, 11P, etc.) were estimated
from field morphologic data using the soil development index. The index values
were compared with values for soils of known age that formed under similar
conditions of climate and, where possible ,parent material (Taylor,
1986.i.Taylor, 1986;; Reheis and others, 1989.i.Reheis and others, 1989;,
1992.i.Reheis and others, 1992; Harden and others, 1991a; Slate, 1992.i.Slate,
1992;), and "best" ages and age ranges were assigned to th esoil profiles.
Harden and others (1991b).i.Harden and others (1991);, using a statistically
based version of this technique in a study of soil chronosequences in the
southern Great Basin (some of the sites used in this study), suggested that
average rates of most soil-development parameters within this area are precise to
about a factor of two and that, at least for Holocene soils, estimated ages
derived from these rates might be accurate within about a factor of two or three.
Laboratory Analyses.
Most of the samples were analyzed using standard laboratory techniques (Singer
and Janitzky, 1986.i.Singer and Janitzky, 1986;) for grain size, CaCO3 and
organic-matter content, pH, and salt content, except that the total salt
equations in Singer and Janitzky, published with an error, were corrected using
a multiplication factor of 0.32 rather than 320. pH for the soils sampled
specifically for this study was measured in 1:1 H2O, whereas the pH for soils
from other sources was measured using CaCl2. Some other analytical techniques
for the Kyle Canyon soils were also different because the soils formed in
carbonate-rich alluvium. The contents of CaCO3 and silt plus clay reported in
this table were measured using a combination of chemical, microscopic, and
photographic techniques (Sowers, 1988; Reheis et al., 1992) and are the amounts
of pedogenic (non-parent material) carbonate and silt plus clay, not total
amounts. In addition, the salt content reported for Kyle Canyon soils is for
gypsum only, not total salt.
Determination of profile weights of soil components.
In this study, we assume that the dust component of soils is pedogenic, not
parent material, and that all silt, clay, and CaCO3 present in greater
proportions in a soil than in the parent material is pedogenic material and
ultimately derived from dust. Soils that formed in carbonate alluvium are one
exception; they contain abundant CaCO3 derived from solution of the parent
material (Sowers, 1985; Reheis and others, 1992). The major-oxide composition
and clay mineralogy of the dust and soil horizons support this assumption.
Previous work in the study area (McFadden, 1982; McFadden and others, 1986;
Taylor, 1986; Reheis and others, 1989, 1992) indicated little chemical
weathering in soils of this age. Soils that are more than about 100,000 years
old or that formed in semiarid to subhumid climates have likely been
chemically weathered. However, much of the silt, clay, and CaCO3 in older
aridic soils is likely to be of eolian origin, in part transformed into other
minerals or grain sizes by chemical or physical processes.Profile weights for
Coyote Mountains soils (AC and FC) were recalculated from original data
because profile weights given in Goodmacher and Rockwell (1990) did not
account for parent-material values.
Major Element Analyses
In order to compare the soil analyses with those of nearby dust samples, which
did not include Ca from CaCO3, the contents of major oxides in the soil
samples from Kyle Canyon and Silver Lake were recalculated on a CaCO3-free
basis (Wilson Creek soils contained no CaCO3).
Clay Mineralogy
Observed differences between the clay mineralogy of soils and dust at some
sites are attributed either to clay formation within the soils, to variability
not explored sufficiently because too few samples were analyzed, or to
slightly different analytical procedures used for the soil and dust samples
(different ion saturations, etc.). In addition, the published reports used
different methods to estimate abundances of clay minerals from peak heights on
X-ray diffraction traces.
Bulk Density of Soil Horizons
At most sites, the parent material consisted of alluvial-fan deposits,
commonly debris flows. Debris flows are usually unsorted and unbedded, so the
content of silt, clay, and CaCO3 in a C horizon formed in these deposits was
assumed to be representative of that originally present in the other horizons.
For soils at Wilson Creek that formed in fluvial deposits potentially
containing fine-grained overbank sediment (Harden and Matti, 1989), amounts of
silt and clay in the parent material of the A and B horizons were estimated to
be greater than those in the C horizons. Basalt flows were assumed to contain
no silt, clay, or CaCO3 when deposited.
Soil Accumulation Rates
Soil accumulation rates must be treated with caution for the following reasons:
(1) Variation in amount of a pedogenic material is expectable for soils of the
same age because soils are inherently variable. Data from more than one
profile per geomorphic surface is critical for quantitative soil studies (e.g.
data for field properties of soils at Silver Lake; Reheis and others, 1989).
Standard deviations were only calculated for the interval rates at the
Fortymile Wash area, Silver Lake, the Cima fans, Wilson Creek, and the Coyote
Mountains, which had quantitative data for more than one profile per surface
(file "intrtdev.xls"). Excluding soils that were strongly eroded or leached,
the standard deviations average 75% of the rates, but range widely (5-200%).
(2) There are uncertainties in the assigned ages of the geomorphic surfaces
and their soils. This problem is most acute for the youngest deposits; for
example, if a deposit is thought to be 200 years old but in fact is 400 years
old, an error of only 200 years would yield a doubled accumulation rate. In
addition, radiometric ages are available only for soils from Silver Lake, the
Fortymile Wash area, Kyle Canyon, and the Coyote Mountains. We have not
included age uncertainties in the calculation of interval rates because
generally the minimum and maximum ages greatly exaggerate the probable errors.
For studies in which the ages of soils were better constrained, as at Silver
Lake and Fortymile Wash, interval-rate uncertainties calculated from the
minimum and maximum soil ages were similar to the range of standard deviations
calculated using replicate soils of the same age.
(3) Assumptions and simplifications were used in the calculations of profile
weights of pedogenic materials, mainly in the estimation of parent-material
values and of bulk density (in this study, a range of 1.2-2.0 g/cm3), which is
difficult to measure accurately in gravelly deposits (Vincent and Chadwick,
1994).
Trap locations were ascertained by plotting their positions on USGS topographic maps at 1:24000 scale.
Soil development index data (as is found in the file DSINDPRN.XLS) was generated for Silver Lake samples but is not yet ready for release.
Sampling Procedures
This report includes the results of investigations performed by several
investigators at Silver Lake, or on samples collected at Silver Lake.
Two labeling standards have been followed.
The first is a system which numerically encodes information about locality,
unit sampled, the profile sampled and the collector of the sample.
A) If the first number is 1, the sample number corresponds to a lower fan
locality and 2 refers to an upper fan locality.
B) The first number following the decimal represents the fan unit on which
the soil was sampled: 1=Qf1, 2=Qf2, etc.; this is the same as the profile
numbers elsewhere.
C) The second number is the profile number on that surface in that fan
position: the first described is 1, the second 2, etc.
D) The last number is only used for one profile, 1.231 to 1.235, because we
had five different people describe the same soil profile separately. Thus
there are five descriptions of this profile but it was only sampled once.
Example 1: Sample 1.110 = a sample from the lower fan area, fan unit Qf1,
and is the first profile sampled.
The second system is alpha numeric.
A) The first set of characters indicates the locality and collection
year. A label for a sample collected at Silver Lake in 1985 would begin
"SL85".
B) The next character indicates the position of the sample site on the
fan. A, B, C, D samples are from the lower fan and W, X, Y, Z samples are
from the upper fan.
C) The second character indicates which profile in a sequence of profiles
described in one position on the fan. A = the first profile described, B =
the second profile described etc.
Example 2: Sample SL85-1A = a sample from the lower fan area, fan unit
Qf1, and is the first profile sampled. (it is also equal to sample 1.110 of
example 1)
Example 3: A sample labeled 2.340 in the numeric system equals a sample
labeled SL85-3Z in the alphanumeric system and would indicate a sample from
the upper fan area, from fan unit Qf3, and it would be the fourth profile
sampled.
Soil Descriptions
Numbered profiles (11H, 11P, etc.) were sampled specifically for this
study. Two profiles from San Felipe Creek (SF1 and SF3) are unpublished
data contributed by Tom Rockwell (San Diego State University). Methods
for the descriptions of all of the soils were the same.
Soil Development Index Values
The soil development index (Harden, 1982) provides a means of quantifying
field properties of soils in order to compare their development. Index
values of field properties including rubification, melanization, paling,
lightening, texture, structure, dry consistence, pH decrease, pH
increase, and carbonate are calculated for each profile using a
spreadsheet template (Taylor, 1988). Horizon and profile index values
are given for all of the soils sampled for this study.
Laboratory Analyses
Most of the samples were analyzed using standard laboratory techniques
(Singer and Janitzky, 1986.i.Singer and Janitzky, 1986;) for grain size,
CaCO3 and organic-matter content, pH, and salt content, except that the
total salt equations in Singer and Janitzky, published with an error,
were corrected using a multiplication factor of 0.32 rather than 320. pH
for the soils
The salt content reported for Kyle Canyon soils is for gypsum only, not
total salt. Data for Kyle Canyon (KC) soils is from Reheis and others
(1992).
Calculation of Profile Weights
The bulk density for each soil horizon, if not measured by previous
reports using either the paraffin-clod method or the excavation
technique, was estimated from particle size and the contents of gravel
and organic matter using the technique of Rawls (1983).
The contents (percentages) of soil components in each horizon were
subtracted from the contents estimated to have been present in the parent
material multiplied by the bulk density of the less-than-2mm fraction and
by horizon thickness, and then summed for the soil.
Debris flows are usually unsorted and unbedded, so the content of silt,
clay, and CaCO3 in a C horizon formed in these deposits was assumed to be
representative of that originally present in the other horizons.
Soils at Wilson Creek that formed in fluvial deposits potentially
containing fine-grained overbank sediment, amounts of silt and clay in
the parent material of the A and B horizons were estimated to be greater
than those in the C horizons.
Basalt flows were assumed to contain no silt, clay, or CaCO3 when
deposited.
Major Element Analyses
In order to compare the soil analyses with those of nearby dust samples,
which did not include Ca from CaCO3, the contents of major oxides in the
soil samples from Kyle Canyon and Silver Lake were recalculated on a
CaCO3-free basis (Wilson Creek soils contained no CaCO3).
Clay Mineralogy
Observed differences between the clay mineralogy of soils and dust at
some sites are attributed either to clay formation within the soils, to
variability not explored sufficiently because too few samples were
analyzed, or to slightly different analytical procedures used for the
soil and dust samples (different ion saturations, etc.). In addition,
the published reports used different methods to estimate abundances of
clay minerals from peak heights on X-ray diffraction traces.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints: None
(703) 648-5285 (voice)
(703) 648-6560 (FAX)
kfoley@usgs.gov
U.S. Geological Survey Open-File Report 95-1
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards (or with the North American Stratigraphic Code). Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
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(703) 648-5285 (voice)
(703) 648-6560 (FAX)
kfoley@usgs.gov
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