Geology
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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