Forensic Geology Techniques

1 - Materials

All geological materials have an original source and geological age.

1A - Hard

Minerals

Crystallography, Mineralogy, Optical mineralogy thin sections, polished thin sections, polished sections, XRD, chemical tests, electron microprobe.

Rocks

Igneous, Metamorphic and Sedimentary.

Mineralogy, Textures, particle shape and size, Optical mineralogy thin sections, polished thin sections, XRF, chemical tests, electron microprobe, absolute dating.

Man-made materials of a geological origin

Bricks, tiles, ceramics, glass, metals and alloys,

Crystallography, Mineralogy, Optical mineralogy thin sections, polished thin sections, polished sections, XRD, chemical tests, electron microprobe.

Fossils

Identification and relative dating, absolute dating.

Water

From rivers or groundwater.

Isotopes

1B- Soft

Poorly consolidated sediments - may be true geological deposits of great age, or recently deposited sediment or weathering products such as soils.

Particle sizing

Sieving, laser particle sizing,

Particle identification, shape analysis, particle statistics.

Sand and silts

Particle analysis as above, heavy mineral analysis, geochemistry, microfossils, environmental analysis.

Gravels

Particle analysis as above, clast types and origin, geochemistry, microfossils, environmental analysis.

Clays

Particle sizing by decanting, clay mineral identification by XRD, geochemistry by XRF, microfossils, nanofossils, palynology.

Air-bourn particles

Palynolology, geochemistry.

2 - Site investgation

"Trace Fossils" - e.g. footprints

As well as the size and make of the footwear (and therefore possible source) - we can gather information about height, speed, direction, changes of direction, water content of the substrate and perhaps even the surrounding environment and season of the year.

In stratigraphy we work on the principle that the oldest sediment is at the bottom, unless it has been turned upside down and we consider ‘cross cutting’ relationships. Remember that the sediment on a suspects footwear has been turned upside down!

Geophysics - non-invasive ground surveys (as seen on Time Team)

To find changes in the soil, subsoil or rockhead - such as grave cuts and ditches.

Resistivity, magnetic, ground penetrating radar, seismic, metal detactor.