Download Ch 13 Soil Analysis notes

Chapter 13
Soil Analysis
“Life is hard. Then you die. Then they throw dirt in your face. Then the worms eat you. Be grateful it happens in
that order.”—David Gerrold, American science fiction writer
Introduction
 Factors such as ____________________________________________________________ in the soil influence the
production of soil.
 Soil from different locations can have different physical and ________________________characteristics.
 Because of this, soil analysis has been helpful in such things as ____________________________ to crime scenes
and _____________________________________________.
Forensic Geology
 The legal application of earth and soil science
 Characterization of ______________________________ that have been __________________________________________
________________________ and the analysis of possible _________________________________________
Forensic Geology History
 1887–1893—Sir Arthur Conan Doyle wrote about scientific ideas and techniques for solving crimes in his
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writings of Sherlock Holmes. This included information about ___________________________________ which had
never actually been used.
1893—An Austrian criminal investigator, _____________________________, wrote that there should be a study of
“dust, dirt on shoes and spots on cloth.” He observed, “________________________________ can often tell us more
about where the ________________________________________________________________________________.”
History
_____ - _________________, a German forensic scientist, presented the first example of _______________________
used as evidence in a criminal case, the ____________________________________________________.
1910—_______________________, a forensic geologist, was most interested in the fact that _____________________
from the crime scene to the criminal. This helped to establish his principle of transfer.
Soil
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Definition—_______________________________________________that cover the earth’s surface and are capable
of _________________________________________
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The Earth
75%—oceans, seas and lakes
15%—_______________________________________
____—suitable for agriculture
Soil Composition
C. Soil is part of the top layer of Earth’s crust.
 It contains ________________________________________________________, and air in varying amounts.
 Soil texture describes the _______________________________________ that make up soil.
 The 3 main grain sizes are ___________________________________.
 The 3 subcategories of soil are ________________________________.
Soil Profiles
Soils are formed in layers (horizons):
 ______________________, ___ horizon, is made of decaying organic matter.
 Topsoil, the A horizon, is a _________________________________________.
 ____________________ makes up the E horizon.
 Subsoil, the ________________, is made of clay and minerals.
 ___________________, the C horizon, has very little humus present.
 Solid rock makes up the ___________________.
Chemistry of the Soil
The pH scale shows how acidic or basic something is. 0-____________ 7-____________ 14
An important chemical property of soil is whether it is acidic or _________________________________
 Materials that make up a soil are not the only factors that affect its pH level.
________________________can change the pH value of a soil.
________________________________ also can change the pH value of soil.
 The pH value of a soil sample can help a forensic scientist match it to other samples.
Soil Comparisons
 May establish a ___________________________________ to the crime, the ___________, or the suspect(s)
 Physical properties—____________________________________________________________
 Chemical properties—pH, _______________________
Probative Value of Soil
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Types of earth material are _______________________________. They have a ____________ distribution and change
over ___________distances.
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As a result, the _______________________________________ of a given sample having properties the same as
another is ________________
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Evidential value of soil can be ______________
 Rare or unusual ___________________
 Rocks
 Fossils
Increasing Probative Value
 ______________________________________
Minerals
 More than _______________have been identified
 Twenty or so are commonly found in soils; _________________________________________
 Characteristics for identification—_____________________________________________________________________
 ________________________
 Types
Rocks
of minerals
 Natural—like granite
 Man-made—like concrete
 Formation
Fossils
 _______________
 _______________
 _______________
 Remains of ____________________________
 May help geologists to determine the __________________
 Some are ______________ and can be used to identify _________________________________
Palynology
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The study of ___________________________
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Variation in ____________________________
Important to know:
 What is _____________________ in a ____________________
 The __________________________________
Soil Evidence
 Class characteristics—the _____________________ may have similar characteristics at the ______________________
_______________ crime scene, on the ______________________________________
 Individual characteristics—________ if the soil has an unusual or specialized ingredient such as ________________
_____________________________________
Soil Collection
In order to present credible evidence in court, a ____________________________________________________.
 A person_______ the evidence, marks it for _________________, seals it, and signs it across the _______________
__________ (above, left).
 It is ___________________ to a technician in a lab for _________________ who opens it, but ___________________
______________.
 After analysis, the technician puts it back into the evidence bag, ____________________________________, and
signs the ___________________________ (above, right).
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Soil Examination
The presence of soil __________________________ can show that a suspect or victim must have been in that area.
__________________________________ taken from shoes or the wheels of vehicles can show a suspect was present
at a series of locations.
Explain how each of the following is useful in the examination of soil samples:
– looking at samples ________________________
– X-ray ______________________
Sand
Sand is the term applied to natural particles with a _________________________________________________.
Its color and contents are dependent upon the ___________________ and surrounding __________________________.
Sand Characteristics
 Composition is based on the ________________________________; also gives the sand its _______
 Texture is determined by the way the _____________________________________
 ____________________________________
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Sand
The action of _________________________________________ forms sand.
This may take _______________ of years.
Because water acts as a buffer, water produces sand ________________________ than wind.
Wind-blown sand becomes _______________________________ because the grains strike each other directly
without a buffer.
Mineral Composition of Sand —Continental and Volcanic Sand
Note that the identifying feature of ________________________________ is quartz; whereas there is no quartz in
volcanic sand. Skeletal sand ______________________ when mixed with an acid. __________________________ is
not a result of weathering but an example of depositions.
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Sand Types
Continental sands—formed from __________________________________ rock, usually _______________
Ocean floor sands—formed from____________________ material, usually___________
Carbonate sands—composed of various forms of _________________________________
_____________________—formed when calcium ions from underground springs precipitate with carbonate ions in
the salt water of a salt lake
Sand Evidence
“In every grain of sand is a story of earth.” —Rachel Carson
 Class characteristics—the type of sand may have similar characteristics to the _____________________________
___________________ crime scene, on the suspect or on the victim
 Individual characteristics—only if the sand has an ___________________________________________________.
Forensic Geology in the News
A 9-year-old’s body was found in a wooded area along a river in Lincoln County, South Dakota. A forensic
geologist collected soil samples from the fenders of a suspect’s truck and the area where the body was found. Both
soils contained grains of a blue mineral that turned out to be gahnite, a rare mineral that had never been
reported in South Dakota. As a result, the soil tied the suspect to the crime.
Read The Coors Kidnapping case-study pp. 305-306