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Title: Cover Page


1
Cover Page
Module 10 The Effects of Topography and Parent
Materials on Soil at Mount Lemmon and Biosphere 2
Center
Adam Nix Eli Pristoop J.C. Sylvan
Yuko Chitani Mei Ying Lai Lily Liew Asma
Madad
SEE-U 2001 Biosphere 2 Center, AZ Professor Tim
Kittel, TA Erika Geiger
2
Introduction Soils
Soil is one of the most important bases of
terrestrial ecology because it provides a variety
of requirements for plants and animal life. The
principal properties that soil provides for
plants are anchorage, moisture storage (in that
soil is like a sponge storing water), and a
supply of nutrients. Soil creates habitats for
animals by providing space for them to live and
by determining the local chemistry. One of
the many definitions of soil is The
unconsolidated mineral matter on the surface of
the earth that has been subjected to and
influenced by genetic and environmental factors
such as parent material, climate (including
moisture and temperature effects), macro-and
microorganisms, and topography, all acting over
time and producing a productsoilthat differs
from the material from which it was derived by
many physical, chemical, biological, and
morphological properties and characteristics.
(as quoted in J. P. Kimmins, 1997, Forest
Ecology a Foundation for Sustainable Management,
2nd edition, Prentice Hall Press.) Many
animals play important roles in the soil,
including insects (springtails, beetles, and
ants), mites, millipedes, nematodes, annelids,
mollusks, burrowing vertebrates, mycorrhizae,
bacteria, and plant roots. Desert soils are not
turned over very often, but ants and burrowing
mammals do most of the turnover that occurs.
Plant roots also do much of the initial breaking
of the parent material into smaller components.
Soil has been called the least renewable
resource in the ecosystem. Unlike biodiversity,
plant growth, water resources, and most other
components, soil takes decades to be replenished
if it is lost.
Steve Slaff talks with students about the soil
profile at the summit of Mt. Lemmon.
The three most important mechanical
properties of soil are texture, structure, and
porosity. Texture is the composition of the soil,
or simply, what the soil is made up of. Some
soils are made up of sand, silt, and clay.
Determining the texture of a soil is a process
that will be further explained in the
methods. The structure deals with the shape, size
and grade of particles. Soil structure refers to
how the individual sand, silt, and clay particles
are arranged into stable aggregates Porosity or
pore space of soils is calculated from the Bulk
Density (Db) and Real or Particle density (Dp).
Texture, structure and organic matter are all
important in determining the overall soil
porosity. Coarse textured sandy soils have larger
pores but much less pore space than finer
textured clay soils.Soil is the link between the
organic and inorganic world.
3
There are five factors that determine how a soil
develops.
  • Parent material
  • Particle size- dune sand vs. clay alluvium
  • Chemistry, soluble limestone vs. decomposing
    granite vs. resistant basalt
  • Regional Climate
  • Temperature- cold favors humus accumulation
    organic material is added faster than it
    decays heat allows humus to decompose rapidly.
  • Water flux- mineral leaching by high rainfall vs.
    Caliche formation under low rainfall.
  • Organisms
  • Organic matter input- acidic pine needles vs.
    grass roots.
  • Vegetation cover determines rate of organic
    input and rate of surface erosion.
  • Bioturbation due to prairie dogs, earthworms,
    termites, etc.
  • Topography
  • Water flow
  • Whether a soil will be eroded, stable, or covered
    by more deposits.
  • Solar radiation loading, which affects soil
    temperature and evaporation rate.
  • Time
  • Soil genesis It takes time for soil to develop
  • Surface stability
  • Climate changes-the longer the time, the more
    likely that climate will change.
  • Human disturbancegrazing, land use, and fire.

Steve Slaff describes the parent materials in the
Santa Catalina Range.
Both physical and chemical weathering are
needed for soils to form. Weathering is the
process of physical and chemical changes in
rocks, which are caused by atmospheric agents
such as water, oxygen, and carbon dioxide.
Weathering takes place at the earths surface.
Weathering may involve the disintegration of
rocks into smaller particles, or the
decomposition of rocks into different minerals.
Long-term weathering often forms various kinds of
clays. In this lab we examined soils
from two different sites, analyzed, and compared
them. What differences or similarities do soils
from different topographical areas have? What
differences could topographical factors have that
influence the kind of soil and soil production?
4
Horizon Definitions
L, F, H O LAYERS
The second component of soil structure is
referred to in terms of soil horizons. The
materials arriving at the surface layer, such as
leaf litter and other dead organic matter, are
processed within each horizon and then pass
through to the layer beneath it. The horizons are
abbreviated to single letters, and unfortunately
the nomenclatural systems differ between
continents. The top layer is the litter layer
(L), composed of litter that is slowly
decomposing and has been only recently deposited,
but is rapidly being broken down by biotic
activity. The next layer is the F layer, a
rapidly decomposing layer of litter leading to an
accumulation of a layer of raw humus (horizons
H and O - horizon O has material that is more
decomposed than horizon H) below it. The H layer
has litter that has been broken down to particles
and is usually very nutrient rich. Below the
humus layer, are the alluviated layers (A
horizons), layers that are very poor in metallic
elements like iron and aluminum, elements which
have been leached out (alluviated) of the forest
floor to the B horizons below. The alluviated B
horizons are layers that are rich in deposited
iron, aluminum, and other minerals (alluviated)
that were leached out of the A horizons. Below
the B horizons lies material that are not
considered soilthe C horizon consisting of
unweathered parent material or compacted rock
materials. The C horizon begins the bedrock
layers, where biological activity is almost
non-existent.
A LAYER
B LAYER
C LAYER
? The soil profile at the Mt. Lemmon site notice
the four distinct layers (or horizons) in the
bank.
5
Map of Two Sites
Mt. Lemmon
Biosphere 2 Center
6
Map of Regional Soil Profiles
MH2- Haplustolls- shallow, moderately slowly to
slowly permeable soils that formed in eolian
material over residuum derived from
basalt. TS6-Torrertic Haplustolls (New
classification Torrertic Hoplustolls) clayey
texture and deep wide cracks that are open more
than 6 months in most years formed in clayey
sediments, soft shales, or basic rocks, in
association with Aridisols and with aridic
subgroups of Ustolls. TS7-The Caralampi series
consists of very deep, well drained soils formed
in fan and slope alluvium from granitic and
volcanic rock. -very gravelly sandy loam -
rangeland. TS10-The Cellar series consists of
shallow and very shallow, somewhat excessively
drained soils formed in slope alluvium from
granitic rock.- very gravelly sandy loam
rangeland. FH5-Mirabal Baldy- Mt. Lemmon site.
Loamy sand. Bolsa quartzite.
7
Climate Diagram of Mt. Lemmon Area
Courtesy of the Desert Research Institute
website http//www.wrcc.dri.edu
8
Methods
Using screen sieves, we separated each
horizon of the soil profile into 5 different
particle sizes (5 mesh-gravel, 10 mesh-fine
gravel, 60 mesh-course sand, 230 mesh-fine
sand, bottom pan-silt and clay). Using a balance
scale, we weighed each of the particle types from
each of the horizons (Tables 12). We then used
Excel to determine the percent composition for
each horizon at each site. Another part of
testing the soils texture was with a flow chart
that helped determine the texture of the soil by
feel. We then tested each horizon from each site
on the plasticity and stickiness of the soil.
Using the Munsell soil color charts for both the
dry and wet soils, we identified soil colors
according to a standard that is universally
acknowledged. We then smudged these colors on a
white piece of paper for better contrast
(Results).
In this lab we wanted two different soil
types, so we collected a soil survey from Mt.
Lemmon, from an elevation of 8,500 feet. To
collect proper sample we labeled each horizon of
soil, clearly distinguishing one horizon from
another. After labeling the horizons we measured
the depth of each horizon. In order to get the
purest sample of each horizon we dug a vertical
profile. This vertical profile allowed us to dig
at the side of the soil, which helped prevent
other horizons from contaminating the sample. We
then carefully bagged the soil from each horizon
and labeled them. This method of sampling was
also used on the soil profile at the Biosphere 2
Center campus. The second soil profile was
collected at 3,852 feet. After we took
these samples, we analyzed them at the dry lab.
We performed a series of tests, such as the sieve
screen test, plasticity tests, texture makeup
tests, the smudge test, and the Munsell soil
color test. The sieve screen test has five pans,
and 4 of the pans have screens filtering
particles from largest to smallest, and the last
pan collects what remains. The mesh sizes are 5,
10, 60, and 230. A mesh size is an indication of
the number of openings per linear inch. This
test allowed us to separate soils to examine
their texture on four different levels.
Excavating a soil profile at the Biosphere2 site.
9
Geologic Formations Mt. Lemmon and Biosphere 2
Center
  • Mount Lemmon Naco group metamorphosed
    Paleozoic sequence, mostly limestone, Bolsa
    quartzite
  • Biosphere 2 Center Dissected Neogene basin fill,
    overline terrace and pediment gravel sheets and
    local alluvium

10
O
O
A
A
B
B
C
C
R
Top Mt. Lemmon soil profile analysis, Mei and
Adam working on the texture tests. Bottom
Biosphere 2 soil profile analysis, Asma working
on the Munsell color and smudge Tests.
Top Mt. Lemmon profile (Letter denotes layer)
Bottom Biosphere 2 soil profile
Top Detail-view of Mt. Lemmon soil
profile Bottom Detail-view of Biosphere 2 soil
profile
A
B1
A
B2
B1
B2
11
Pyramid of Soil Texture
Biosphere2
Mt. Lemmon
12
Table 1 Mount Lemmon
Lat/Long 32.44 N / 110.78W, Elevation 2764
meters, 8500 feet Site Description Old growth,
near summit, cooler, breezier climate, more
rainfall, more organic materials
13
Soil Composition Mount Lemmon
14
Table 2 Biosphere 2 Center
Lat/Long 32.57 N / 110.84W , Elevation 1174
meters Site Description Arid, Desert, grasses,
small trees, succulents shrubs, less than 10" of
rain, alluvial deposition
15
Soil Composition Biosphere 2 Center
16
Results
  • Based on the Texture Analysis and the Munsell
    Color Test, the soil profiles of Mt. Lemmon and
    Biosphere 2 are as follows
  • Mount Lemmon
  • O 3cm black/brown, charcoal, leaf litter
  • A 0-26cm dark grayish brown, sandy loam
  • B 26-46cm yellowish brown, sandy clay loam
  • C -46-156cm brown weathered rock, loam
  • Bedrock -156
  • Biosphere 2
  • A 0-30cm brown, sandy clay loam
  • B1 030-50cm reddish brown, clay
  • B2 -50-85cm yellowish red, sandy clay loam
  • B3 -85 - yellowish red, sandy clay loam
  •  
  • The Screen Sieve Analysis was affected by
    imprecise methods (see conclusion)
  • Mount Lemmon
  • Gravel accounted for the largest percentage of
    mass from O to C layers.
  • Coarse sand accounted for most of the non-gravel
    mass.
  • With increasing depth, percentage of silt and
    clay decreased.
  • Biosphere 2

Smudge Tests
17
Discussion Parent Material, Topography Soil
  • The unconsolidated mineral matter on the
    surface of the earth that has been subjected to
    and influenced by genetic and environmental
    factors such as parent material, climate
    (including moisture and temperature effects),
    macro-and microorganisms, and topography, all
    acting over time and producing a
    productsoilthat differs from the material from
    which it was derived by many physical, chemical,
    biological, and morphological properties and
    characteristics.
  • To investigate this working definition for soil,
    we were asked to consider two questions
  • What differences or similarities do soils from
    different topographical areas have? And what
    differences could topographical factors have that
    influence the kind of soil and soil production?
  • To answer these we took soil from two distinct
    topographical localesone from a road cut near
    the top of Mt. Lemmon (elevation 8,500 ft.), the
    other from a road cut on the Biosphere 2 campus
    (elevation 3,852 ft.). We looked at soil
    texture, color, consistency, structure we also
    looked at the topography, climate, and the
    general characteristics of each site.
  • Of the five functional factors that make soil
    (topography, parent material, time, organic
    forces, and climate) we found topography and
    parent material to have the most pronounced
    affect on the texture, structure, and the
    physical and chemical characteristics of our
    samples.
  • Not that climate, biotic activity, and time are
    unimportant to soil development, but parent
    material and topography have shape how these
    other (crucial) factors function. The parent
    material at a given site influences the
    interaction between organic and inorganic
    materialse.g. quatz and limestone weather
    differently and so form very different soils.
    Topography is a deciding factor in the
    microclimate. Elevation effects temperature and
    moisture levels at a given site these in turn
    are limiting factors for the vegetation growing
    there and the kind of organic material that they
    into the soil.

Eli takes a closer look at the clay.
One note about time. Though it is a passive
agent in this process, it is perhaps the key
ingredient in the creation of soils. The process
of physical and chemical changes in rocks caused
by atmospheric agents such as water, oxygen, and
carbon dioxide takes place over millions of
years. Soil is a living process (a living
labyrinth, Tony Burgess calls it) and like most
living things it takes time to develop.
18
Mount Lemmon
TOPOGRAPHY At 8,500 feet, the Mount Lemmon site
is a breezy mountaintop characterized by its cool
temperatures and old growth forest. Ponderosa
and Limber Pines, Douglas and White Firs all
tower 60 ft or more over the forest floor. In
the space between these trees, small stands of
Quaking Aspens and Rocky Mountain Maple saplings
grow. Part of the reason for high biotic
productivity in the area has to do with an
abundance of rainfall 788mm of precipitation per
year on average, according to the nearby
Palisades Ranger Station which has been compiling
yearly climate data for years (see above table).
These forests benefit from late summer monsoons,
as well as snowfall in late fall/early winter.
Referring to the local climate of the Santa
Catalina Mountains, the Arizona AgNIC reports,
On high peaks at 9000 to 10,000 feet, snow
persists all winter and accumulates to 20-40
inches. Summer rains fall June - September,
originate in the Gulf of Mexico, and are
convective thunderstorms. Winter moisture is
frontal, originates in the Pacific and Gulf of
California, and falls as rain or snow in
widespread storms of low intensity and long
duration. May and June are the driest months of
the year. Humidity is generally low. Temperatures
are mild in the summer to cold in the winter.
Freezing temperatures are common from October
through April. Frost free period ranges from 120
to 260 days.
We were surprised at first to discover less
biodiversity of plant and arthropod life at this
site, but given the colder temperature
regime--the minumum daily temperature in the
Santa Catalinas drop below freezing during four
months our of the yeara chill that many plants
thriving in the lower elevations around
Biosphere2 could not tolerate. Thus because of
its topography, the microclimate on Mount Lemmon
is much like that found in temperate forests at
higher latitudes. Vegetation contributes a
substantial amount of organic material to the
soil profile every year as reflected in the L, H,
and O layers of the soil profile. We estimated
this to be 3cm in our profile. It is worth noting
that we could expect more given the sheer amount
of organic activity at Mount Lemmon. The fact
that there was not a thicker O layer is strong
evidence of the effect of erosion on overall soil
formation at higher topographical points. The
deep roots of the trees, and the life forms that
they support, also help to break down the soil
structure through the process of biturbation.
These dense networks of roots and the burrows of
vertebrates and arthropods that live on the
forest floor provide conduits for water thus
aiding in the process of weathering of the rock
material. Another contributor to the character of
this O layer has been fire. Charcoal found in the
litter over the O layer suggests a history of
forest fires in the area. These fires allow for
a much more rapid decay of organic material and
nutrients than normal decomposition. Judging from
the vegetation, there has not been a fire in
recent years. Human disturbance even when it has
profound impact of a local ecology does not tend
to have any long term geological effects for
this reason it is considered more of a historical
phenomenon than a geological one. In an indirect
way, topography also influences human disturbance
and land use policy. Mount Lemmon is a popular
tourist site and is used primarily for recreation
purposes. Land use in the immediate area is
limited to these activities, though there is a
great deal of construction on roads in the area.
Currently these are the only significant
disturbances to the soil.
19
Temperate forest near the top of Mount Lemmon.
PARENT MATERIAL According to Steve Slaff, the
rock material that forms the basis of our Mt.
Lemmon site is called Bolsa Quartzite. (He also
referred to it as Cat Mountain Rhyolite.) The
rock formations in this area were probably laid
in the Pleistocene period and influence the soil
type here, known as Mirbal Baldy. There is almost
no volcanic material in the Santa Catalina Range
of which Mt. Lemmon is a part. The parent
material is broken down over time in the C layer
of the soil. This fact plus the enormous amount
of organic material available to the process are
perhaps the two most distinguishing factors from
the Biosphere 2 site.
20
Biosphere 2
Topography Compared with Mt. Lemmon, the
landscape of our second site is limited mostly by
availability of water. This biome would be best
classified as Apacherian mixed scrub savanna,
which, according to Dr. Tony Burgess, is
classified as coexisting growth forms that
include grasses, subshrubs, stem succulents and
shrubs (Burgess 1994). Long dry spells
punctuated by erratic and variable rainstorms
make for a very unstable plant community. This
area has a much larger percent composition of
grasses than the site on Mt. Lemmon. This makes
the whole community susceptible to frequent fire
and thus limits extensive long-term productivity.
The pattern of dry periods followed by heavy
rains means that summer storms cause erosion.
Plants have had to adapt their root structure to
these extreme conditionsgrasses have quick
growing shallow roots to take advantage of the
heavy summer rains, trees and some shrubs tend to
send deeper roots into the soil to take of water
that seeps deeper into the profile during winter
storms. Warm average temperatures protect
species vulnerable to frosttrees like the
mesquite, and succulents. Sandy soils work to
the advantage of these type of trees, since they
are more porous and allow for more water during
the characteristic heavy storms to penetrate
deeper into the soil profile. Another factor in
the topography of this site is extensive grazing.
While the ground directly above our sampling
site did not appear to have been grazed recently,
the Apacherian savanna has historically been
overgrazed. Overgrazing can erode the soil, by
trampling microorganisms that help knit the soil
structure together. They also significantly
reduced the amount of biotic material available
to the soil process. When cattle are introduced
to the ecosystem, much less biotic material and
nutrients are returned to the soil. Compared to
the Mt. Lemmon site, there is very little litter
at the Biosphere 2 Center. The topography is
marked islands of fertility under trees where
litter and hungry nutrient grasses tend to gather
leave top soil levels vulnerable to erosion.
This may have had something to do with why we
found no O layer at the Biosphere 2 site.
21
  • Parent material The geological basis of
    Biosphere 2 is called the Cordones Surface. It
    is part of an ancient alluvial fan deposited by
    runoff from the Catalina Mts. during basin and
    range faulting. The Cordones Surface formed from
    mixed alluvial deposits of different kinds of
    rocks including Paleozoic sedimentary rocks,
    metamorphic rocks, and Tertiary granites Since
    then, two processes have prevailed over time in
    the creation of this soil composition. Eluviation
    occurs when water percolating down through the
    soil leaches substances out of the upper layers.
    The acidic water dissolves most minerals, except
    quartz, and carries them deeper into the soil.
    Illuviation occurs as water percolating down
    through the soil carries materials from upper
    layers into deeper layers. An illuvial soil
    horizon has accumulated clays or minerals
    transferred by water flow from overlying soil.
    Over time these two processes can change a
    uniformly mixed alluvial deposit into a mature
    soil with distinctly different horizons
    (Burgess). This explains why we found clay
    interspersed many rounded rocks in the soil
    horizon.
  • Clay comes some from weathering within the
    original deposit but most is brought in as
    windblown dust and raindrop nuclei. This dust
    often consists of oxidize iron-based material
    which give the soil a ruddy appearance. You can
    see this in the smudge tests the samples from B2
    are much redder than those on Mount Lemmon.
    Percolating water gradually moves clay particles
    down through the soil. In early stages this
    forms clay films on clods and pebbles. As clay
    continues to accumulate, water movement within
    the horizon is slowed hence clay is not moved
    into deeper layers, forming with is called an
    argillic horizon. On ancient alluvial fans, such
    as the Biosphere 2 campus, Holocene erosion has
    exposed the Pleistocene argillic and calcic
    horizons. These exposed layers become parent
    material for new soil formation. This process is
    typical of lower elevations in the Basin and
    Range Geologic Province. Over time the low level
    of precipitation (usually less than 12 inches per
    year) forms a horizon of caliche, a cement layer
    made from calcium carbonate (Burgess). This
    layer is almost nonexistent in areas of greater
    and more consistent precipitation (like the
    temperate forests of the Northeast), but we found
    that it was very prevalent on the B2C campus.
    The presence of caliche was one of the major
    differences between the soil profiles.
  • McAuliffe in his essay on desert soils in the
    Natural History of the Sonoran Desert describes
    the slow process by which caliche horizons are
    formed They start as thin, patchy coats of
    whitish calcium carbonate on the lower surfaces
    of pebbles and small stones.These
    weakly-developed calcic horizons can form within
    a few thousand years. Accumulation of more
    calcium carbonate eventually produces thicker,
    continuous coatings on pebbles and stones or
    pronounced whitish nodules in fine-grained parent
    materials. Eventually, additional accumulation of
    calcium carbonate fills the soil interstices
    between pebbles or nodules and the calcic horizon
    becomes plugged, greatly restricting the downward
    movement of water. Once this occurs, calcium
    carbonate may continue to accumulate on the top
    of the calcic horizon in hard, cemented layers
    and may literally engulf and obscure overlying
    soil horizons in the process. It takes many tens
    to hundreds of thousands of years for such
    strongly-developed calcic horizons to form.
    Sometimes hard, whitish caliche becomes exposed
    on the surfaces of very old soils when erosion
    removes overlying, less erosion-resistant soil
    horizons. These partly eroded soils are very
    common throughout the Sonoran Desert and are
    called truncated soils.
  • Thus the presence of a caliche layer not only
    tells us something about the content of the soil,
    it also serves as evidence of the climate that
    created it. The thick caliche layer we found in
    out Biosphere 2 sample would suggest that this
    area has experienced extreme aridity for quite
    some time. It can also give us a picture of the
    future topography and soil composition since
    caliche erodes unevenly to create exposed or
    slightly buried surfaces that shed water in
    weathering crevices, resulting in a landscape
    with patchy water infiltration and retention,
    and facilitating even more run-off, and more
    erosion, during heavy summer thunderstorms
    (Burgess). The geology of the landscape also
    exacerbates many of the environmental/climatic
    factors that shape this community and the soil
    profile, and creates a patchwork of different
    soil textures and characteristics. This is
    partly why desert soils are so hard to classify.

22
The Formation of Caliche in Arid Soils
From Phillips and Comus. 2000. Natural History of
the Sonoran Desert. Arizona Desert Museum Press.
Tucson.
23
Conclusion
  • How did the soils differ? How does topography
    affect local climate? How did different parent
    materials result in different soils?
  • In this exercise, we learned various
    techniques for sampling and examining soil
    profile. For example
  • Sieve test
  • Texture tests smudge test, ribbon (plasticity)
    test, stickiness test
  • Munsell Color Test
  • Topography affects climate, and together,
    these two factors significantly influence the
    soil composition. The higher elevation of Mount
    Lemmon results in more rainfall, and a more
    breezy climate. The lower elevation of Biosphere
    2 results in a dryer, hotter climate. Analysis
    of the soils indicated that the Mount Lemmon soil
    had more gravel and organic material in it than
    the Biosphere 2 soil, whereas the Biosphere 2
    soil had more coarse sand in it. This is because
    the Mount Lemmon site has a colder climate, where
    litter decomposes more slowly than in the arid
    climate at the Biosphere 2. The arid climate
    here results in less rainfall which, in turn,
    favors the formation of caliche found in the
    Biosphere 2 soil.
  • Differences in the parent materials of the
    soils also influence soil composition. Bolsa
    quartzite was the parent material of the Mount
    Lemmon soil this material resulted in the
    softer, easily broken apart, weathered rock found
    in one of the soil layers. The parent material
    of the Biosphere 2 soil is alluvial deposits.
    Rust in the alluvial deposits results in the rust
    color of the soil at the Biosphere 2.
  • In analyzing the soil samples collected, we
    learned that there are not many quantitative
    tests that can help us accurately describe the
    soil composition percentages. Most of the
    results that we obtained were from qualitative
    assessments, such as the Color Test and the
    Smudge Test. We found discrepancies that might
    have a lot to do with how we implemented these
    tests.
  • In the future, we need to collect sufficient
    amount of soil so that we can replicate our test
    for more accurate results.

Soil profile Biosphere 2 ?
24
References Acknowledgements
http//www.columbia.edu/itc/cerc/seeu/bio2/index.h
tml http//homepages.which.net/7Efred.moor/soil/f
ormed/f0107.htm http//www.statlab.iastate.edu/soi
ls/osd/dat/C/CABEZON.html http//ialcworld.org/soi
ls/nonaridisols/nonaridisols.html http//www.statl
ab.iastate.edu/soils/osd/dat/C/CARALAMPI.html http
//www.statlab.iastate.edu/soils/osd/dat/C/CELLAR.
html http//interactive.usask.ca/skinteractive/mod
ules/agriculture/soils/soilphys/soilphys_depo.html
http//www.wrcc.dri.edu McAuliffe, Joseph R.
Desert Soils. A Natural History of the Sonoran
Desert. Eds Steven J. Phillips. Arizona-Sonora
Desert Museum Press Tucson, 2000 Burgess, T.
1995 Desert Grassland, Mixed Shrub Savanna,
Shrub Steppe, or Semidesert Scrub? Pp.31-67 in
The Dilemma of Coexisting Growth Forms.
University of Arizona Press, Tucson. Dickinson,
William R. 1992. Geologic Map OF Catalina Core
Complex And San Pedro Trough Arizona Geological
Survey contributed Map CM-92-C. 1125,000
Geological Society of America Special Paper
264. Macbeth, Gretag. MUNSELL SOIL COLOR
CHARTS year 2000 Revised washable Edition.
MUNSELL COLOR 617 Little Britain Road, New
Windsor, NY 12553. Steve Slaff Lecture on geology
and soil. 6/19/01, Mt. Lemmon, AZ.
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