Chapter 13 Soil Analysis Life is hard Then

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 Chapter 13

In Soil Analysis you must: § § § Identify a soil’s common constituents Determine the origin of a soil sample Interpret a topographic map Understand the concept of spectrophotometry Forensic Soil Convention Chapter 13 1

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…and… Chapter 13 § analyze and present data mathematically using graphs § Why soils can be used as class evidence § When soils can be used as circumstantial evidence 3

(Review) Circumstantial evidence: additive collection of facts used to infer a conclusion about something unknown; a theory, supported by a significant quantity of corroborating evidence explained by an expert witness in court. Chapter 13 4

Soil is considered Ø Trace evidence that is easily transferred anywhere. Ø Physical evidence Ø Class evidence Chapter 13 5

Forensic Geology § The legal application of earth and soil science § Characterization of earthen materials that have been transferred between objects or locations and the analysis of possible origin or sources Chapter 13 6

Forensic Geologist Tools § § § Binocular microscopes Petrographic microscopes X-ray diffraction Scanning electron microscopes Microchemical analysis Chapter 13 7

History § 1887– 1893—Sir Arthur Conan Doyle wrote about scientific ideas and techniques for solving crimes in his Sherlock Holmes books. This included information about soil and its composition which had never actually been used. § 1893: Austrian criminal investigator, Hans Gross, wrote that there should be a study of “dust, dirt on shoes and spots on cloth. ” He observed, “Dirt on shoes can often tell us more about where the wearer of those shoes had last been than toilsome inquiries. ” Chapter 13 8

History continued § 1904—Georg Popp, German forensic scientist, presented the 1 st example of earth materials used as evidence in a criminal case, the strangulation of Eva Disch. § 1910—Edmond Locard, was a forensic geologist, and was most interested in the fact that dust was transferred from the crime scene to the criminal. This helped to establish his principle of transfer. Chapter 13 9

Soil: Naturally deposited materials covering earth’s surface and are capable of supporting plant growth The Earth 75%—oceans, seas and lakes 15%—deserts, polar ice caps and mountains 10%—suitable for agriculture Chapter 13 10

Soil Formation C. § § § Living matter—plants, animals, microorganisms Inorganic materials Climate Parent materials Relief—slope and land form Time Chapter 13 11

Soil Profile § Topsoil § Subsoil § Parent material Chapter 13 12

E. Composition § Sand § Silt § Clay § Organic matter Chapter 13 13

Soil F. Nutrients— macro § Nitrogen § Phosphorus § Potassium § Calcium § Magnesium § Sulfur Nutrients—micro G. § § § § Manganese Iron Boron Copper Zinc Molybdenum Chlorine Chapter 13 14

Soil Collection of soil samples depends on the circumstances of the crime. Indoor scenes will differ from outdoor scenes in the type of evidence that can be recovered and the way in which these samples are collected. Chapter 13 15

Outdoor evidence in soil… Chapter 13 Kendall/Hunt Publishing Company 16

Soil Comparisons § May establish a relationship or link to the crime, the victim, or the suspect(s) § Physical properties—density, magnetism, particle size, mineralogy § Chemical properties—p. H, trace elements Chapter 13 17

Making an impression… if the shoe fits. . . http: //www. crimeandclues. com/soil_analysis. htm Chapter 13 18

Probative Value of Soil (ability to prove something) § Types of earth material are virtually unlimited. They have a wide distribution and change over short distances. § As a result, the statistical probability of a given sample having properties the same as another is very small § Evidential value of soil can be excellent Chapter 13 19

Increasing Probative Value Rare or unusual minerals § Rocks § Fossils § Manufactured particles § Chapter 13 20

Minerals § § § More than 2000 have been identified Twenty or so are commonly found in soils; most soil samples contain only 3 to 5 these minerals Characteristics for identification: size, density, color, luster, fracture, streak, or magnetism Chapter 13 21

Rocks § § Aggregates of minerals Types § Natural—like granite § Man-made—like concrete § Formation § Igneous: lava-volcanic § Sedimentary: “settled” limestone § Metamorphic: formed under pressure: gneiss Chapter 13 22

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Fossils Remains of plants and animals § § May help geologists to determine the age of rocks Some are scarce and can be used to identify regions or locations § Chapter 13 25

Palynology The study of pollen and spores § Important to know: § § What is produced in a given area § The dispersal pattern § Variation in size and weight For additional information about palynology visit: http: //science. uniserve. edu. au/faces/milne. html http: //www. geo. arizona. edu/palynology/ Chapter 13 26

Trilete spores. Such spores are the earliest evidence of life on land Chapter 13 27

Pollen on a car Chapter 13

Forensic Palynology: A person was found hanged in a barn in what appeared to be a suicide, however, police were suspicious because the hanged person had not been depressed nor had he left a suicide note. There were five people the police believed had a motive to kill the person, and each would directly profit by the victim's death; nevertheless, each suspect had an alibi. Chapter 13 29

A forensic pollen analysis of the rope used to hang the victim contained pollen commonly found on a farm where vegetables were being grown. One of the five suspects owned a small truck-farm and made a living from selling a variety of vegetable crops. Chapter 13 30

Although this single piece of evidence was not enough to convict any suspect, it helped police narrow their suspects to one individual. Through careful surveillance of the primary suspect, the police were able to gather enough evidence to arrest the suspect for the man's murder. Chapter 13 31

We are here

Soil Evidence § Class characteristics—the type of soil may have similar characteristics at the primary and/or secondary crime scene, on the suspect or on the victim § Individual characteristics—only if the soil has an unusual or specialized ingredient such as pollen, seeds, vegetation, or fragments. Chapter 13 33

Sand § § Sand is the term applied to natural particles with a grain diameter between 1/16 mm and 2 mm. Its color and contents are dependent upon the parent rock and surrounding plant and animal life. (The photo on the right shows color differences in sand from six locations around the world. ) Chapter 13 34

Sand Characteristics § § Composition is based on the material of the source; also gives the sand its color Texture is determined by the way the source was transported § Shape rounded, squared off or star shaped § Grain size large…small Chapter 13 35

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Sand Types Continental sands—formed from weathered continental rock, usually granite § Ocean floor sands—formed from volcanic material, usually basalt § Carbonate sands—composed of various forms of calcium carbonate § Tufa sands—formed when calcium ions from underground springs precipitate with carbonate ions in the salt water of a salt lake § Chapter 13 37

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 primary and/or secondary crime scene, on the suspect or on the victim § Individual characteristics: only if the sand has an unusual ingredient or contaminant. Chapter 13 38

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Virtual Sand Lab Take a look at other examples on the website from the Geology Department at Pasadena City College. www. paccd. cc. ca. us/SAND/Sand. Exrc. htm Or look at more sand Chapter 13 40

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A creature which taxonomically belongs to Family Calcalinidae, Order Foraminiferida, Class Rhizopoda, Phylum Protozoa. Its scientific name is Baclogypsina sphaerulata. It is distributed from Tanegashima Island towards the subtropical and tropical areas. Individual size is around 1 mm, its skeleton is with 5~6 processes, making it a real star shape. Locally, the star sands occur abundantly, sometimes they are more than true sand grains in some beaches. In Iriomote Island, it can be found at every beach when we look for it carefully, in particular it is abundant at Hoshizuna Beach. Chapter 13

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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. Check out other cases at: www. forensicgeology/science. htm Chapter 13 45