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Chemistry for the Analysis of Trace Evidence > Geology > Flashcards

Geology Flashcards

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1
Q

What are some examples of samples for forensic geology?

A
  • rocks
  • sediments
  • soils
  • dusts
  • minerals
  • fossiles
  • concrete
  • bricks
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2
Q

What are sediments, soils and dusts made from?

A

mixtureso of organic and inorganic particles

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3
Q

What are some examples of inorganic fractions?

A
  • rock fragments
  • mineral grains
  • amorphours matter
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4
Q

what are some examples of organic fractions?

A

made from biological processes
* shells
* forams
* phytoliths
* diatoms
* CHO based products (coal)

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5
Q

Where are rocks encountered in forensics?

A
  • weights to sink bodies
  • in bags containing illicit substances/firearms
  • as concealment material in smuggling cases
  • projectiles
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6
Q

What are the three main classifications of rocks?

A
  1. igneous
  2. metamorphic
  3. sedimentary
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7
Q

What is diatomaceous earth made from?

A
  • diatoms
  • clay minerals
  • iron oxide
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8
Q

What are the four forms of sediments in size order from largest to smallest?

A
  1. gravel
  2. sand
  3. silt
  4. clay
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9
Q

Where is gravel encountered in casework?

A
  • tyre treads
  • shoe soles
  • drowning victims mouth/respiratory tract/clothing
  • associated adhesive tapes
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10
Q

Where is sand encountered in casework?

A
  • beaches
  • sand dunes
  • construction sites
  • found on/in footwear, clothing, vehicles, bodies, washing machine filters, U-bends of sinks and toilets
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11
Q

Where is mud encountered in casework?

A
  • on skin
  • under fingernails
  • on clothing/footwear
  • in/on vehicles
  • from coastal/river floodplains
  • fields
  • woodlands
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12
Q

What makes up soil?

A
  • non-living: inorganic material, salt crystals, decaying plant/animal matter, shells, insect exoskeletons, fossils, bones, teeth
  • living: bacteria, algae, fungi, plant roots, invertebrates, small mammals
  • unusal: cement, plaster, metallic fragments, glass, paint flakes, paper, fibres, plastic fragemtns
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13
Q

How is dust used in casework?

A
  • chemcial composition can vary a lot - indicative of geographical area
  • can be transported thousands of miles
  • natural, industrial, household, street, water sources
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14
Q

What are the uses for vermiculite mineral?

A
  • insulating material in fire resistant safes
  • chimneys
  • brake-lining
  • floor screed, concrete
  • fire-proof walls
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15
Q

What is anthropogenic and what are some examples?

A

man made
* concrete
* bricks
* glazed ceramics
* plastic fragments
* fibres
* paint flakes
* glass fragments
* metal fragments

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16
Q

What are some recovery considerations for soil?

A
  • package in a paper bag or
  • freeze in a tamper evidence bag to reduce yeast or fungal growth
17
Q

What is the analytical workflow for soil?

A
  1. gross examination, recovery and collection
  2. preliminary evaluation of physical characteristics
  3. polarised light microscope
  4. microspectrophotometry - colour determination
  5. measurement of pH and electrical conductivity
  6. IR - organic content
  7. Raman - inorganic and carbon content
  8. SEM-EDX - SE mode for topology and BSE for homogeneity
  9. XRD - crystal structure and polymorphs
  10. AAS, XRF, ICP-AES - elemental composition
  11. isotopic analysis
  12. MVA = HCA and PCA
18
Q

What are the physical characteristics of soil?

A
  • weight
  • volume
  • colour
  • texture
  • for individual particles: dimensions, surface area, perimeter, shape
19
Q

What mainly makes up mud?

A

silt and clay

20
Q

What makes something mud?

A

any sediment that has a sticky character when wet

21
Q

What determines soil type formation?

A
  • climate
  • parent material
  • age
  • bio activity
  • topography

Chemistry for the Analysis of Trace Evidence (16 decks)

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