Isoscape
Definition
A map of isotope ratio variation across a geographic area, derived from systematic sampling of soil, water, plant, or mineral material; used to compare the isotope signature of an object against the spatial distribution of expected values and assign it to a geographic region.
- Key isotopes used
- Oxygen, hydrogen, strontium, carbon, and nitrogen. Oxygen and strontium isoscapes are the most established for forensic applications.
- Primary forensic applications
- Human geographic tracing, timber provenance, mineral and artifact sourcing, and biological sample geolocalization.
- Data sources
- Monitoring stations, systematic field sampling of soil and water, and interpolation using geological or climate model output.
Common questions
What is an isoscape used for in forensics?+
An isoscape is a geographic map that shows how isotope ratios (like oxygen, strontium, or hydrogen) vary across a region. Forensic investigators use it to match an unknown sample's isotope signature against the map and estimate where that sample likely originated, whether it's human remains, timber, minerals, or other materials.
How are isoscapes built?+
Isoscapes are created by systematically collecting samples from soil, water, plants, or minerals across a geographic area and measuring their isotope ratios. These measured values are then interpolated to create a continuous spatial map, sometimes using geological, hydrological, or climate model data to fill gaps.
Which isoscapes are most useful for tracing human origins?+
Oxygen and hydrogen isoscapes are the primary tools for geographic tracing of humans. Strontium isoscapes are also well-developed for forensic use. Each isotope moves through the environment in predictable ways (through water, diet, or geology), so matching a person's tissue isotope values to the appropriate isoscape can narrow down their geographic origin.
Related terms
- δ18O (Delta-18-O)
- The ratio of oxygen-18 to oxygen-16 in a sample expressed in per-mil deviation from the Vienna Standard Mean Ocean Water (VSMOW) standard....
- δ2H (Delta Deuterium)
- The ratio of deuterium to hydrogen in a sample expressed in per-mil deviation from VSMOW. Covaries with δ18O along the global meteoric...
- 87Sr/86Sr Ratio
- The ratio of radiogenic strontium-87 (produced by decay of rubidium-87) to the stable reference isotope strontium-86. Values range from roughly 0.703 in...
- Chloroplast Microsatellite (cpSSR)
- A short tandem repeat locus in the chloroplast genome. Maternally inherited and non-recombining in most trees, cpSSR haplotypes diverge geographically and are...
- Delta-C-13
- The ratio of carbon-13 to carbon-12 in a biological sample, expressed relative to a standard (VPDB). Distinguishes C3 plant diets (wheat, rice;...
- Delta-C13 / Delta-N15
- Stable carbon and nitrogen isotope ratios in tissue, expressed as deviation from a reference standard (delta notation). They reflect diet composition and...
- Delta-N-15
- The ratio of nitrogen-15 to nitrogen-14, expressed relative to atmospheric nitrogen. Increases by approximately 3-4 per mil with each step up the...
- FaceLab
- The digital facial approximation software developed at the University of Manchester and extended at Liverpool John Moores University by Caroline Wilkinson's group....
- Fluid Inclusion
- A microscopic cavity in a crystal trapped at the time of growth, containing the mineralising fluid or melt; analysed by microthermometry (freezing...
- Gerasimov Method
- The Russian anatomical facial approximation technique developed by Mikhail Gerasimov from the 1930s, in which the facial muscles are individually reconstructed on...
- Global Meteoric Water Line (GMWL)
- The linear relationship δ2H = 8 × δ18O + 10 that describes the global co-variation of O and H isotopes in precipitation....
- ICP-MS
- Inductively coupled plasma mass spectrometry: the laboratory reference method for trace element quantification in food matrices. Uses high-temperature argon plasma to atomise...
Explained in these topics
- DNA and Isotope Methods for TimberA geographic map showing predicted or measured isotope ratio values across a region. Species-specific isoscapes for timber are built from reference specimens o...
- Forensic Facial Approximation and Stable-Isotope Geographic ProvenanceA geographic map of isotope ratios (typically oxygen or strontium) showing how the ratio varies spatially across a region or globally. Used as a reference to m...
- Gems, Minerals, and Artefacts: Geological ProvenanceA map of isotope ratio variation across a geographic area, derived from systematic sampling of soil, water, plant, or mineral material; used to compare the iso...
- Oxygen and Hydrogen IsoscapesA spatially continuous map of predicted isotope values across a geographic area, built by interpolating data from monitoring stations and sometimes using clima...
- Population Genetics, Geographic Provenance, and Stable IsotopesA continental or global map of expected stable isotope ratios: typically Sr-87/86, delta-C13, or delta-N15: interpolated from measured values at known location...
- Strontium and Lead Isotopes in GeoforensicsA spatial map showing the geographic variation of an isotope ratio across a region. Sr and O isoscapes are the most developed for forensic use. They are built...