Parent Material and Soil
Formation
Created by
Jim Ippolito
&
Mike Hanna
College of Agricultural Sciences
Colorado State University
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Colluvium Photo:
Source: http://pubs.usgs.gov/of/2002/of02-437/gallery.htm
Type of Parent Material: Colluvium
Mode of Transportation: Gravity
Degree of Sorting by Particle Size: Low
Additional Information: The term colluvium classifies parent
material transported by gravity. Colluvium is made up of a
heterogeneous mixture of boulders, rocks, pebbles, and soil
from upslope areas. Thus the degree of particle sorting is
low.
Background Photo Source: Jim Ippolito; Northern boundary of Rocky Mountain National Park, Colorado
Glacial Till Photo Source: Dr. Paul McDaniel;
http://soils.ag.uidaho.edu/soilorders/entisols_06.htm
terminal moraine
Type of Parent Material: Glacial Till
Mode of Transportation: Ice
Degree of Sorting by Particle Size: Low
Additional Information: Parent material
transported by ice is called glacial till.
This parent material is found where
glaciers have deposited material, such as
in terminal or lateral moraines. Ice is a
poor sorter of particles, and thus glacial
till contains everything from the smallest
clay-sized fraction to rocks, pebbles, and
boulders.
Background Photo Source: Jim Ippolito; Northern boundary of Rocky Mountain National Park, Colorado
Background Photo Source: http://hvo.wr.usgs.gov/volcanoes/haleakala/1koolau_large.jpg
Type of Parent Material: Tephra
Mode of Transportation: Wind
Degree of Sorting by Particle Size: High
Additional Information: Parent material
transported via volcanic ejecta is called
tephra. The mode of transportation is
wind. Wind is a good sorter of particles.
Larger particles tend to bounce on the
Earth’s surface while smaller particles are
transported greater distances.
Soil developed from volcanic ejecta.
Soil Profile Source: http://soils.usda.gov/technical/classification/orders/andisols.html
Aeolian Photo:
Source: Dr. Paul McDaniel;
http://soils.ag.uidaho.edu/soilorders/entisols_06.htm
Type of Parent Material: Loess or Aeolian
Mode of Transportation: Wind
Degree of Sorting by Particle Size: High
Additional Information: Parent material
transported by wind is called loess or
aeolian. Wind is a good sorter of
particles. Larger particles tend to bounce
on the Earth’s surface while smaller
particles are transported greater
distances.
Background Photo Source: http://www.nps.gov/grsa
Type of Parent Material: Alluvium
Mode of Transportation: Water
Degree of Sorting by Particle Size: High
Additional Information: Parent material
transported by flowing water (streams,
rivers) is called alluvium. Water is a good
sorter of soil particles. Larger particles
(i.e. sands) settle out of water first, and
smaller particles (i.e. clays) settle out of
water last. Thus, you tend to find sandsized particles closer to the water source
and clay-sized particles further away.
Soil developed from alluvium.
Source: http://www.mo15.nrcs.usda.gov/features/gallery/houlka.html
Type of Parent Material: Lacustrine
Mode of Transportation: Lake
Degree of Sorting by Particle Size: High
Additional Information: The term lacustrine
classifies parent material transported by a
lake. Water is acting on the parent material
and thus there is a high degree of particle
sorting.
Lacustrine Deposit Profile Source: NRCS staff,
http://houzi.org/lacustrine.html
Type of Parent Material: Marine
Mode of Transportation: Ocean
Degree of Sorting by Particle Size: High
Additional Information: The term “marine” classifies
parent material transported by oceans. Water is
acting on the parent material and thus there is a
high degree of particle sorting.
Soil Profile Source: http://www.mo15.nrcs.usda.gov/features/gallery/ocilla.html
Soil Profile Source: http://www.mo14.nc.nrcs.usda.gov/features/goldston.html
Type of Parent Material: Residual or Residuum.
Mode of Transportation: In place; none.
Degree of Sorting by Particle Size: Low
Additional Information: The terms residual or
residuum classify parent material formed in
place (i.e. non-transported). The degree of
sorting is low because no other factors have
influenced soil movement.