Geology Flashcards
What are some examples of samples for forensic geology?
- rocks
- sediments
- soils
- dusts
- minerals
- fossiles
- concrete
- bricks
What are sediments, soils and dusts made from?
mixtureso of organic and inorganic particles
What are some examples of inorganic fractions?
- rock fragments
- mineral grains
- amorphours matter
what are some examples of organic fractions?
made from biological processes
* shells
* forams
* phytoliths
* diatoms
* CHO based products (coal)
Where are rocks encountered in forensics?
- weights to sink bodies
- in bags containing illicit substances/firearms
- as concealment material in smuggling cases
- projectiles
What are the three main classifications of rocks?
- igneous
- metamorphic
- sedimentary
What is diatomaceous earth made from?
- diatoms
- clay minerals
- iron oxide
What are the four forms of sediments in size order from largest to smallest?
- gravel
- sand
- silt
- clay
Where is gravel encountered in casework?
- tyre treads
- shoe soles
- drowning victims mouth/respiratory tract/clothing
- associated adhesive tapes
Where is sand encountered in casework?
- beaches
- sand dunes
- construction sites
- found on/in footwear, clothing, vehicles, bodies, washing machine filters, U-bends of sinks and toilets
Where is mud encountered in casework?
- on skin
- under fingernails
- on clothing/footwear
- in/on vehicles
- from coastal/river floodplains
- fields
- woodlands
What makes up soil?
- 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
How is dust used in casework?
- chemcial composition can vary a lot - indicative of geographical area
- can be transported thousands of miles
- natural, industrial, household, street, water sources
What are the uses for vermiculite mineral?
- insulating material in fire resistant safes
- chimneys
- brake-lining
- floor screed, concrete
- fire-proof walls
What is anthropogenic and what are some examples?
man made
* concrete
* bricks
* glazed ceramics
* plastic fragments
* fibres
* paint flakes
* glass fragments
* metal fragments
What are some recovery considerations for soil?
- package in a paper bag or
- freeze in a tamper evidence bag to reduce yeast or fungal growth
What is the analytical workflow for soil?
- gross examination, recovery and collection
- preliminary evaluation of physical characteristics
- polarised light microscope
- microspectrophotometry - colour determination
- measurement of pH and electrical conductivity
- IR - organic content
- Raman - inorganic and carbon content
- SEM-EDX - SE mode for topology and BSE for homogeneity
- XRD - crystal structure and polymorphs
- AAS, XRF, ICP-AES - elemental composition
- isotopic analysis
- MVA = HCA and PCA
What are the physical characteristics of soil?
- weight
- volume
- colour
- texture
- for individual particles: dimensions, surface area, perimeter, shape
What mainly makes up mud?
silt and clay
What makes something mud?
any sediment that has a sticky character when wet
What determines soil type formation?
- climate
- parent material
- age
- bio activity
- topography
