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Forensic geology at the International School Science Fair 2013

Duncan Pirrie1, Laurance Donnelly2, Gavyn K. Rollinson3, Alan R. Butcher4, Lorna

A. Dawson5 & Heather A. Pirrie1

1Helford Geoscience LLP, Menallack Farm, Treverva, Penryn, Cornwall, TR10 9BP, UK

dpirrie@helfordgeoscience.co.uk 2IUGS, Initiative on Forensic Geology (IFG), Wardell Armstrong International, 2 The

Avenue, Leigh, Greater Manchester, WN7 1ES, UK ldonnelly@wardell-armstrong.com 

3Camborne School of Mines, CEMPS, University of Exeter, Penryn Campus, Treliever

Road, Penryn, Cornwall, TR10 9EZ 4FEI Natural Resources, Achtseweg Noord 5, Eindhoven, The Netherlands 5James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH

In July 2013 the International School Science Fair (ISSF) was hosted by

Camborne Science and International Academy, Cornwall, UK. This meeting brings

young talented scientists together from around the world to participate in

workshops and activities highlighting current scientific developments. As part of

ISSF 2013, a workshop on forensic geology was delivered to some of the

international participants. This included the preparation of a map showing the

mineralogical composition of the participating schools soils. The soil mineralogy

was determined using automated mineral analysis based on scanning electron

microscopy. In addition workshops on the recovery of geological trace evidence

in a forensic context and the theory and practice of carrying out a geophysical

search for hidden items. Data generated as part of this workshop are available to

download from the International Union of Geological Sciences, Initiative on

forensic geology website (www.forensicgeologyinternational.com).

The International School Science Fair (ISSF) is an annual gathering of young scientists

from around the world. The idea was originally conceived in 2004 at the Australian

Science and Mathematics School in Adelaide, South Australia, when educators from

many countries, including Australia, Singapore, Thailand, Korea and Japan came

together and shared their reflections and understandings regarding student and teacher

engagement in science and mathematics. The ISSF was officially launched in 2005 to

act as a platform for budding scientists to display their scientific knowledge and defend

their findings in a non-competitive setting. The event provides students from around the

world with valuable opportunities to work in collaborative settings to exchange ideas,

polish their research techniques and engage their inquisitive minds on the sciences with

like-minded peers. In particular, the team-work for the problem solving and sharing

sessions gives students and educators the chance to work with peers from different

nations, thus promoting the intercultural understandings essential for life in the 21st

Century. The ISSF model has evolved over the past few years, so that it now engages

with universities, local government, non government organisations (NGOs) and

research institutions. This takes place in a multi-disciplinary and multi-national network

that provides the ISSF participants with world-class venues for authentic experiences

and education.

This year, in July 2013, the ISSF came to the United Kingdom (UK) for the first

time hosted by the Camborne Science and International Academy, Cornwall. As part of

a range of geological activities including visits to the test mine at the Camborne School

of Mines, where students were able to explore the mineralization, geology and mining

which helped to make Cornwall famous, the International Union of Geological Sciences,

Initiative on Forensic Geology (IUGS-IFG) in collaboration with FEI Natural Resources,

the Camborne School of Mines (University of Exeter), Helford Geoscience LLP and the

Forensic Geology Group of the Geological Society of London were delighted to host a

workshop on the topic of forensic geology. The workshop comprised three main events:

(a) the world soil map 2013 project; (b) a simulated crime scene and geological trace

evidence recovery and analysis exercise and (c) a geological ground search for burials,

such as weapons and items commonly used in crime, using geophysics.

The world soil map project 2013

One of the most common ways in which geology can be used to assist in the detection

of serious crime is the examination and analysis of geological trace evidence such as

soil (see Ruffell and McKinley, 2008; Pirrie and Ruffell, 2012). Soil is a very variable

material and is also easily transferable to items such as clothing or footwear. An

offender contacting exposed soils by for example walking on a surface, or digging, will,

in most cases, transfer soil to their clothing or footwear. Soil is a very complex material

typically composed of naturally occurring minerals derived from the underlying bedrock

geology and more recent superficial deposits, and man-made particulate debris

reflecting the human activities in an area, along with biological materials such as

macroscopic plant debris, organic matter, pollen, spores and micro-organisms. As part

of the ISSF 2013 we wanted to prepare a geological world soil map highlighting the

variability of soils around the globe. To do so, we invited participating schools and

colleges to collect small soil samples from their home locations and send them to us

prior to the event for mineralogical analysis (Fig. 1). On receipt, the soil samples were

examined using a binocular microscope. As expected the soils were visually highly

variable, with variations in particle size and shape, colour, organic content, etc (Fig. 2).

A subsample of each soil was placed into a plastic mould and mixed with epoxy resin.

This was then subsequently polished and carbon coated before being analysed using

an automated scanning electron microscope (QEMSCAN®), at the University of Exeter,

Penryn Campus. Automated mineral analysis has been previously described in Geology

Today, by Pirrie and Rollinson (2011). The surface of the polished block is automatically

examined and when a particle is located, its chemical composition is mapped with the

very rapid capture of energy dispersive X-ray spectra (EDS). Each spectra is then

compared with a library of known spectra and the area analysed assigned to a mineral

name or chemical compositional grouping. In this way each particle within a soil sample

is mapped and assigned to a mineral name. Eighteen soil samples were analysed with

between 5219 and 9320 individual particles analysed in each sample, based on

between 159,168 and 1,296,114 individual EDS analysis points per sample.

The automated mineral analysis provides the overall modal mineralogy of each of

the soils, along with an image of all of the soil particles in which each mineral is

assigned to a different colour. These false colour maps provide an easy visual way to

assess the similarities and differences between the different soil samples (Fig. 3).

Overall, many of the soils shared some minerals in common, but the relative abundance

of those different minerals made each soil distinctive in its own right. So for example,

whilst quartz was present in every sample analysed, its relative abundance varied from

only 8% in a soil from Canada to over 88% in a soil from Thailand. Cassiterite might

have been expected in the soils from Cornwall, where tin was mined for thousands of

years, but was actually only seen in a soil from Malaysia, another important tin mining

region. Of the 18 soils analysed, 16 samples were from different schools/colleges

around the world whilst two samples were analysed from the host school for the ISSF

2013, Camborne Science and International Academy, so that the variability at an

individual location could also be assessed. Each participating school was presented

with a poster showing the mineralogical appearance of their own soil sample. In

addition, all of the soil images were combined together to produce a world soil map

showing the variability of soils around the globe (Fig. 4). These soil posters are

available to download from the IUGS Initiative on Forensic Geology website at

(www.forensicgeologyinternational.com). Furthermore, the soil mineralogy data are also

available to download from www.forensicgeologyinternational.com as a microsoft excel

spreadsheet. These data could be used within the classroom as a teaching resource.

For example, at the ISSF 2013, the students were provided with the mineralogical data

plotted as a series of charts (see below). The students examined both the mineral

abundance charts and the false colour particle images. In general, geological data

cannot be used to prove categorically an association between two items from a forensic

point of view, unless we had two broken fragments of the same original rock. Instead,

geological data is used on an exclusionary basis, in that we can test whether or not the

available data can exclude the possibility that two soil samples were originally sourced

from the same place. The mineralogical data can be used to test which samples could

be excluded as having come from the same location versus which samples could not be

excluded as having been derived from the same location. Since we analysed two soil

samples from the ISSF 2013 host school, these two data sets can be used to replicate

the data we might have from a crime scene and from an object used or worn at that

crime scene. These two samples can then be compared with the data from the other

schools and colleges around the world, which can be excluded as potential sources of

the soil, on the basis of both the overall mineralogy and the particle images.

Geological trace evidence

To bring the event alive for the ISSF we set up several different forensic geology

sampling scenarios. An area of the school's grounds was secured as a crime scene,

complete with ‘crime scene do not cross’ tape and a scene tent set up, provided by

Devon and Cornwall Police. With different participants taking part, and wearing full

personal protective clothing (including overshoes, crime scene suits, face masks and

double gloves) (Fig. 5A), we examined how we might collect soil samples from a

clandestine grave or a location where an object was buried as part of a criminal or

terrorist act (Fig. 5B). Following instructions and demonstrations the students were then

required to carefully collect soil samples from the edges of a grave and seal the

samples using tamper-proof forensic sampling bags (Fig. 5C). Sampling strategies for

surfaces that an offender might have come into contact with were also considered and

samples were collected (Fig. 5D). Once we had collected soil samples we went on to

examine a vehicle for potential trace evidence (Fig. 5E). Earlier in the day several items,

including two spades and several items of footwear had been placed within the vehicle.

Several of these items had soil present on them relating to the burial location, but others

were unrelated to this place. In addition, several small samples of soil were hidden in

the vehicle. Soil was embedded into the brake pedal cover; several small samples of

soil were hidden in the driver foot well and also within the boot (trunk) of the vehicle.

The ISSF participants were then shown how to examine and recover soil evidence from

the vehicle. Whilst several teams correctly found the footwear and digging implements

the smaller samples of soil were over-looked. In an actual forensic scenario it is these

small areas of soil, which may potentially provide the critical physical evidence used

during a subsequent court trial.

The participants visually compared the soils recovered from the vehicle, along

with the soil present on the footwear and spades with a sample of soil which they had

been able to collect from the grave cut (Fig. 5F). Whilst they were able to discount some

of the soils on the basis of colour, other samples could not be excluded on the basis of

colour and texture alone. The previously analysed soil data was then used by the

participants to further test the degree of similarity or otherwise between soils present in

the vehicle, and on the spades and footwear with soil from the grave site. The students

were very quickly able to exclude samples on the basis of the relative abundance of the

minerals present but also by a comparison of the false colour particle images, correctly

identifying which samples were potentially related and which were not (Fig. 5G). The

examination of the vehicle also highlighted how soil forensic examination has improved

in part as a result of being able to analyse smaller and smaller samples, in a cost

effective and timely manner. Historically Crime Scene Investigators might have taken

samples from vehicle wheel-arches or swept the inside of vehicle foot wells, however,

today such samples would not be taken. Why? Because they are mixtures of all the

many places such a vehicle has visited in the past. Much more importantly, we are

looking for evidence of discrete depositional events where a small soil sample in a

vehicle foot well or on the trim of the vehicle relates to a particular individual location.

Geophysical search for buried items

In addition to the recovery of geological trace evidence and its evaluation, participants in

ISSF 2013 were also able to experience some hands-on ground search investigation,

using geological and geophysical strategies and methodologies. The use of geoscience

methods in terrestrial searches has recently been reviewed by Pringle et al. (2012).

Prior to the event a number of items had been placed on the ground surface and buried

at locations on a school playing field. The buried items were intended to replicate

potential weapons. (Figures 6 and 7)

An initial briefing was provided to the students, which included an overview of the

geology, general ground conditions, past and present land use and the presence of any

underground and overhead utilities and other sources of geophysical ‘noise’ (such as

metal fences, man-hole covers and drains) (Fig. 6A). The significance of this was

explained, to determine the most suitable suite of geophysical instruments relevant in

trying to find the items being sought. The importance of press, media and public

management in ground search was also briefly discussed.

A fabricated case was presented to the students. This was based on the

intelligence that an organised terrorist and criminal group had buried a number of items

on the school playing field, and that it was their intention to recover these items at a

later date to be used in a terrorist act or serious crime. The objective of the search was

to locate the buried items. This provided the opportunity for the students to play an

active role in the planning, management and implementation of a high assurance

ground search to prove the presence of, or negate the existence of, the buried items

(known as ‘targets’). Before ‘the search’ began, an introduction to the Winthrop Theory

and human behavioral and psychological aspect of ‘burial’ was provided. This was

followed by an overview and a brief history of the recent developments of police

searches for burials. This outlined how specialist search began in the United Kingdom

Police Service following attempts by the Provisional Irish Republican Army (PIRA), a

proscribed terrorist organisation, who attacked the British Prime Minister, Margaret

Thatcher and her Cabinet. This occurred on 12 October 1984, at the Grand Hotel in

Brighton, during a Conservative Party Conference. As a consequence, five people were

killed and several others were injured. This provided the incentive for the police to

become better trained in search. In the past decade or so, the applications of geology to

ground searches has further advanced search so that there now exists a well-

established and effective programme of search training, search assets and deployment

strategies.

Different search types were discussed, including; ‘search and rescue’ (where a

person is lost or missing but active in their self discovery), a protective (defensive)

search and an offensive (reactive) search; depending on whether the search is

designed to locate buried items to support a prosecution, deprive criminals of their

resources and opportunities to commit crime or to protect vulnerable targets and

venues.

Following the briefing the students conducted a reconnaissance walk-over survey

of the school playing field. This enabled the outer limits of the search area to be

determined, secured and cordoned with ‘crime scene do not cross’ tape. This ‘reccy’

also enabled the soils and general ground conditions to be observed. As a result, the

students were able to assess the diggability of the ground and produce a conceptual

geological model for the suspected buried items. During the ‘reccy’ some of the

students were able to identify evidence for recent digging due to subtle changes in

ground conditions and the vegetation cover. It was explained that in an actual

operational case, these areas may be secured and searched first, in order to focus the

available resources and to obtain a possible ‘quick win’ (although this is not always the

case since ground disturbances may be caused by, for example; geological, biological

or anthropogenic processes).

Next, the student’s established a geophysical control site whereby a series of

ferrous and non-ferrous metal items, believed to be similar to the target items being

sought, were buried in the ground. The control site allowed the students to become

familiar with the operational aspects of the instruments and soil probes (Fig. 6C, D).

Furthermore, this established the maximum detectable resolution of the buried items. A

conventional police style finger-tip ‘line search’ took place, to recover any items of

potential interest that were on the ground surface (Fig. 6B). This consisted of the

students standing side by side, and walking, some crawling, in a systematic and

controlled manner across the playing field. Some non metallic items had been purposely

placed on the ground surface and some of these were found by the students and

recognised as being of potential ‘forensic’ or ‘police’ interest. These included for

example; a cigarette end, part of a plastic fork and a button, from which non-geological

forensic information may potentially be obtained.

The search area was sub-divided into a series of more easily manageable search

lanes, each approximately 1m wide and marked with string and plastic pegs. The

students subsequently scanned each search lane in turn, with a magnetometer (to

detect ferrous metal), followed by an electromagnetic instrument (to detect both ferrous

and non-ferrous metals and alloys). The geophysical instruments were chosen since

they gave a real-time audible indication upon detection. In the limited time available this

negated the use of data processing to generate a geophysical model. Each positive

anomaly (known also as a ‘hit’ or ‘indication’) was marked with a coloured flag or plastic

peg, to identify the type of anomaly produced by each instrument. The students were

instinctively eager to dig and explore these anomalies, but were advised to resist

digging and to continue the geophysical imaging of the search lane. Following the

completion of the geophysical surveys 1.2m long soil probes were used, on a 0.2m grid

spacing. These were inserted into the ground and had the benefit of detecting any items

missed by the geophysics by either recovering small components of the target in the

‘window’ of the soil auger or by the buried target preventing the auger from being

inserted into deeper soil layers. Again, any such locations were marked with a distinct

coloured flag or plastic peg. It was explained to the students that on actual police

searches the deployment of a specialiy trained canine dog and handler may often be

used, depending on the type of items being searched for (such as a shallow, unmarked

homicide grave).

The geophysical and soil probe anomalies were subsequently invasively

investigated, first by the careful removal of the surface layer of turf followed by careful

digging, sub-dividing, quartering and sieving of the displaced soil to locate and identify

the desired target (Fig. 7). The buried items found included an imitation explosive

device (a fake nail bomb, comprising a steel tin with 100mm long nails), a knife, a

garden fork, a crow bar and a spade. It was explained to the students, that at the point

of a positive discovery any further invasive digging by the forensic geologists usually

stops. Further advice is then provided by a specialist who is trained to recovery the

items found in accordance with best practice and in a forensic capacity (Fig. 7). In the

case of a grave this may include for example a forensic archaeologist/anthropologist

under the instruction and management of a crime scene manager. In the case of

weapons and explosive devises specialist military advice may be required for the search

and recovery.

The ISSF soil data as a teaching resource

One of the long term aims of the ISSF meetings is that there should be a longer term

benefit to the participants of the meetings. To foster this aim further we have made the

soil mineralogy data collected as part of the world soil map 2013 project freely available

to download from the International Union of Geological Sciences, Initiative on Forensic

Geology website (www.forensicgeologyinternational.com). On this site are copies of the

modal mineralogy data, soil particle images and copies of the individual school and

college soil posters and the ISSF 2013 world soil map.

Acknowledgements

We are grateful to the Principal of Camborne Science and International Academy, Ian

Kenworthy for inviting us to assist with ISSF 2013 and Vicky Holland-Lloyd and

Rebecca Merritt for their assistance. Financial support for the world soil map project

was provided by FEI Natural Resources, IUGS Initiative on Forensic Geology (IFG) and

Helford Geoscience LLP. Mineral analysis was carried out at the Camborne School of

Mines (University of Exeter) QEMSCAN® facility. Wardell Armstrong International Ltd

allowed the participation of Laurance Donnelly. Anne-Maree Althaus created the world

soil map. Ivor Lloyd and Paul Rogers from Devon and Cornwall Police provided forensic

equipment, and Derek Grove (FERA) assisted with the import of the soil samples.

Finally, we dedicate this article to the talented and enthusiastic young scientists who

attended ISSF 2013 and their teaching staff who make events like this happen.

Suggestions for further reading

Ruffell, A. & McKinley, J. 2008. Geoforensics. Wiley-Blackwell.

Pirrie, D. and Rollinson, G.K. 2011. Unlocking the application of automated mineralogy.

Geology Today, 27, 226-235.

Pringle, J.K., Ruffell, A., Jervis, J.R., Donnelly, L., McKinley, J., Hansen, J., Morgan, R.,

Pirrie, D. & Harrison, M. 2012. The use of geoscience methods for terrestrial

searches. Earth Science Reviews, 114, 108-123.

Pirrie, D. and Ruffell, A. 2012. Forensic Geology and Soils. In Marquez Grant, N. and

Roberts, J. (eds) Forensic Ecology Handbook. Blackwell-Wiley, 183-201.

Figures

Fig. 1. Soil samples were collected from around the world, sealed in sample vials and

sent for mineralogical analysis ahead of the ISSF 2013 meeting.

Fig. 2. The soil samples received for analysis were visually highly variable in terms of

colour, texture, particle size and shape and organic content, for example;(A) Illinois,

USA, (B) Thailand, (C) Malaysia and (D) Indonesia. The maximum field of view in each

image is 13 mm.

Fig. 3. The soil samples were analysed using advanced automated scanning electron

microscopy and each participant received a poster of their soil showing a false colour

particle map of their soil, in this case a soil sample from the Korea Minjok Leadership

Academy, South Korea. Each colour represents a different mineral type; particles

shown are approximately 300 µm across.

Fig. 4. The International School Science Fair (ISSF) 2013 world soil map. Soils from

participating schools and colleges around the world were analysed. The data from this

project are free to download from www.forensicgeologyinternational.com.

Fig. 5. Forensic geology trace evidence recovery and evaluation. (A) Getting prepared

with full personal protective clothing. (B) Recovering soil samples and (C) packaging

them in tamper proof evidence bags. (D) Sampling loose surface materials an offender

may have contacted. (E) Examining vehicle footwells for trace evidence. (F) Soil

adhering to the blade of a spade recovered from the vehicle. (G) Evaluating automated

mineralogy data based on both modal abundance and particle images.

Fig. 6. Forensic geology ground search to determine the location of terrorist or criminal

burials. (A) Initial brief and explanation of geology, diggability, conceptual geological

models, search type and context of the burials. (B) Line search to recover items and

objects on the ground surface. (C) Training and familiarization of the electromagnetic

(total metal detector). (D) Training and familiarization with the magnetometer (ferrous

metal detector) and (E) instruction on its field deployment. (F) Training and

familiarization with the soil probe (auger).

Fig. 7. Location and recovery of targets buried in an unmarked, shallow location. (A)

Initial invasive investigation of a positive geophysical anomaly. (B) Verification of a

positive ‘find’. (C & D) The recovery of a buried object of interest to the police (an

imitation nail bomb). (E) Reinstatement of the soil and surface turf. (F) Establishment of

a crime scene for the recovery of buried targets, located using geological search

strategies and geophysical search assets.