||News & Resources
Geologists Uncover Evidence
Soil And Water
By Robert A.
use the word forensics, most people conjure up images
of TV doctors like Quincy examining a dead body to solve the
crime of the day, or they recall lawyers from programs like
"The Practice" who receive "lab results from
forensics" that change the focus of their case. But,
when I tell them my profession is forensic geology,
most people are not sure what to think. My explanation, I
must admit, is pretty booorrrrring - until I give them a few
MATERIALS AS EVIDENCE
Simply, forensic geology is the scientific application
of earth sciences to legal matters. Practically, this means
that a forensic geologist identifies, analyzes, and compares
earth materials, such as soil, rocks, minerals, and fossils
found on or in a receptor (e.g., a suspect, a vehicle or other
medium of transfer, such as water) to possible source areas
(e.g., a crime scene, an alibi location, and/or a point of
disposal/release). The goal of these comparisons is to establish
the degree of probability that the material was or was not
derived from a particular location; thereby, associating or
disassociating a person or object with that location1. In
other cases, the comparison of earth materials or changes
in materials is used to determine the time an incident occurred,
the cause of an incident and/or responsibility for an incident.
you recall from your science classes that the earth is composed
of igneous, metamorphic, and sedimentary rocks, each with
a variety of minerals and/or fossils that originate in specific
areas, and that these rocks are often changed and/or re-distributed
to other locations by wind, water, biota and/or humans. Overall,
because the sizes, types, and distribution of earth materials
are so varied, the probability is high that earth material
at any location is unique. Therefore, the evidentiary value
of earth materials is excellent, in many cases1. This value
is further enhanced when other sciences, such as botany, paleontology,
biology, and hydrology, provide corroborating evidence.
some attorneys and investigators don't consider soil (dirt,
to some), water, fossils, rocks, or other earth materials
(and sometimes manufactured materials) relevant to their cases,
let alone important evidence. However, by analyzing a piece
of industrial debris or coal, soil particles on shoes and
clothing, types and concentrations of chemicals in groundwater,
the type of gas in a water supply well or storm drain, type
of rock, water chemistry, and/or other earth materials, forensic
geologists often can help identify where, when, and/or how
incidents occurred and who is responsible.
forensic geology is inherently beneficial to neither the plaintiff
nor the defendant; site-specifically, however, it provides
evidence for consideration by all parties:
material in the form of soil provided strong evidence
against a rape suspect when comparison of soil samples
on each knee of his pants matched the soil types from
the right and left knee impressions at the rape scene.1
In other cases, analyses of soil on clothing have been
used to support alibis and show no connection of the suspect
to the crime scene.
identifying the nature and extent of groundwater contamination,
a forensic geologist determined the time a chemical release
contaminated water supplies, thereby identifying, among
several insurance policies, the specific insurance policy
in effect and providing coverage at the time of release.
In another case, a similar analysis plus a chemical degradation
analysis showed that contamination in groundwater at a
company originated at another property and a different
company was responsible for cleanup.
analyzing road maintenance records and techniques used
to sample an unpaved road, a forensic geologist provided
evidence that eliminated the validity of the opposition's
roadway data and skid testing in a motor vehicle accident
case. Geologic analyses of roadways in other cases have
shown that unpaved roads were improperly constructed and/or
WHENEVER TWO OBJECTS COME INTO CONTACT, THERE IS ALWAYS
A TRANSFER OF MATERIAL….
Recent television programs, such as "Crime Scene
Investigators" leads most people to believe that "forensic
geology" is some new science that originated in the United
States. Well, they are only partly correct. It is a relatively
recent science compared to physics and chemistry, but it is
not as new as they think, and it did not originate in the
United States. 1European authors, such as Englishman, Sir
Arthur Conan Doyle, author of the Sherlock Holmes series
of novels from 1887 - 1893, and Austrian, Hans Gross, author
of the 1893 handbook Criminal Investigation, initially
conceptualized forensic geology in their writings.
these literary concepts were put into practice by the director
of the Technical Police Laboratory in Lyons, France, Edmond
Locard, who, in 1929, set forth one of the fundamental tenants
of forensic geology:
two objects come into contact, there is always a transfer
of material. The methods of detection may not be sensitive
enough to demonstrate this, or the decay rate may be so
rapid that all evidence of transfer has vanished after a
given time. Nonetheless, the transfer has taken place. -
Locard's Exchange Principle
high-tech methods of detection become more and more sensitive,
the transfer of material is becoming easier to demonstrate.
[That was the boring part; it gets better soon!]
FORENSIC GEOLOGY SUPPORTS MANY CASES
Usually, the forensic geologist looks for the unusual in a
sample, such as an uncommon mineral, a microfossil, or a chemical1.
But, it may be a simple case of just matching soil, rocks,
minerals, or fossils with a particular location or landforms
with a particular time (i.e., the exchange of materials, as
described above by Locard) that provides assistance to investigators
and evidence in civil and criminal proceedings. From something
as basic as saving time during an investigation and collecting
accurate/available information (e.g., "Dirt on shoes
can often tell us more about where the wearer of those shoes
had last been than toilsome inquiries." - Hans Gross
noted in his 1893 handbook1) to more dramatic uses, forensic
geology covers a broad spectrum of applications:
Under-fender dirt/soil deposited on the road at impact
with the victim was used to locate the car/driver; also,
matching the grease on the victim with the grease under
the car provided supporting evidence1.
Soil on clothing of a suspected rapist was used to place
the suspect at the crime scene and to eliminate the suspect's
alibi; small bits of coal in the soil sample from the
suspects pant cuffs provided additional evidence when
historical aerial photographs showed that coal was stored
at the location of the rape1.
Soil and other earth materials found on murder victims
have been used to determine the location of homicides,
especially when the murder occurs in one location and
the body is disposed in another location. And, using water-current
measurements, forensic geologists have located bodies/objects
thrown into water or, conversely, determined where the
newly discovered body/object originally entered the water.
Also, geologic techniques have been used to locate clandestine
graves and buried weapons1.
Identifying the type of rocks used as weapons led to the
source location of the rocks and helped locate suspects
who were subsequently convicted1.
By determining the natural characteristics of a contaminated
aquifer, the sources of contamination were identified
and property owners at the times of release were identified
and separated from the subsequent owners who had no responsibility
for contamination. Contrarily, a forensic geologist identified
multiple parties that caused groundwater contamination
where previously only one party was believed to be responsible.
Analysis of sediment in a river lead to identification
of parties responsible for water pollution and adverse
fishery impacts. Soil erosion from construction activities
was shown to have caused excessive lake sedimentation.
Geologic techniques were used to show the time a wetland
was illegally drained and filled.
Soil and construction material analyses identified the
cause of a collapsing roadway.
Geologists have identified the location of buried objects,
such as chemical drums, storage tanks, vehicles, waste
disposal trenches, bodies, and weapons.
Soil analyses and geophysical testing was used in several
property condemnation cases to determine the value of
mineral deposits (e.g., sand and gravel).
Insurance Claims - Accidents / Personal Injury
Analyzing the composition of a "gravel road"
showed how it influenced a vehicle accident.
Analysis of site-specific excavation actions and geologic
conditions uncovered evidence that determined the party
responsible for personal injury resulting from an excavation
Evaluating the possible cause of a sewer tunnel explosion
during construction, a forensic geologist showed that
the cause was from human activities and that the explosive
conditions were known and avoidable prior to construction
of the tunnel.
Insurance Claims - Property Damage
By analyzing the type of rocks thrown at new vehicles
being transported on railroad cars passing through several
states, a forensic geologist determined the likely location
of the repeated vandalism; then, authorities caught the
Evaluation of groundwater hydraulics showed how retention/detention
pond caused increased basement flooding. Also, a forensic
geologist provided evidence that showed the extent of
property damage resulting from repeated flooding of a
county drain that was purposely dammed by a riparian owner
to damage another riparian owner up stream. (In addition
to property damage, the downstream owner also attempted
personal injury by shooting at the upstream neighbor.)
Based on current chemical concentrations in the soil and
groundwater, a forensic geologist calculated the original
chemical concentrations to which workers were exposed.
Resolution / Third-Party Expert:
By acting as a third-party expert to provide independent
technical analysis in disputes/mediation/arbitration/court
actions, a forensic geologist has assisted in finding "common
ground", win-win solutions, and/or alternative approaches
when soil or water is a significant issue.
In the more than 70 years since Locard first formulated his
exchange principle, investigators and scientists have applied
the principle and other geologic concepts in developing evidence
to support many types of court cases. Today, courts in the
United States and other countries generally accept forensic
geology as a valid source of scientific evidence1.
Just as forensic geology was conceptualized in the minds of
writers, its applications may be limited only by our imagination.
1. Murray, R.C., and Tedrow, J. C. F. 1992. Forensic Geology,
Upper Saddle River, New Jersey: Prentice Hall.
A. Hayes, CPG is
President and Principal Forensic Geologist at GeoForensics,
Inc., a forensic geology and environmental consulting firm
located in Williamston, MI. He may be reached at 517.655.8348
or by e-mail: email@example.com