How to Use Google Earth to Plan Metal Detecting Hunts in the UK
Walk into any metal detecting forum in Britain — whether that is the National Council for Metal Detecting (NCMD) forum, the Federation of Independent Detectorists (FID) community boards, or the dedicated threads on Detecting Wales and Scottish Detecting groups — and you will quickly find detectorists arguing about one thing above all others: research. The difference between a productive day in the field and a fruitless trudge across a muddy field almost always comes down to the quality of your pre-hunt preparation, and Google Earth sits at the very centre of modern UK detecting research.
This guide covers everything you need to know about using Google Earth effectively to identify productive land, assess terrain, cross-reference historical maps, and build the kind of intelligence file that gives you the best possible chance of recovering significant finds — all within the legal framework that governs metal detecting in England, Wales, Scotland, and Northern Ireland.
Why Google Earth Is a Uniquely Powerful Tool for UK Detectorists
The United Kingdom is, in global terms, an extraordinarily rich country for metal detecting. Thousands of years of continuous habitation, Roman occupation lasting nearly 400 years, Viking settlement, Norman conquest, medieval markets, Civil War skirmishes, and two World Wars have all left stratified layers of material culture beneath British soil. The Portable Antiquities Scheme (PAS), administered by the British Museum and supported by Historic England, recorded over 1.6 million finds between 1997 and 2023, the vast majority submitted by detectorists. Each of those finds came from somewhere — and the question that drives every serious detectorist is: where is the next productive site?
Google Earth answers that question better than almost any other free tool available. Its combination of satellite imagery, historical aerial photography, terrain mapping, street-level integration, and measurement tools makes it indispensable for desk research. Crucially, it also integrates with other essential UK-specific resources, including the Historic England National Heritage List, the Magic Map agricultural and environmental data service, and scanned historic Ordnance Survey maps available through the National Library of Scotland.
Getting Started: Setting Up Google Earth for Detecting Research
Google Earth Pro vs the Browser Version
Google Earth is available in two main forms: the browser-based version at earth.google.com and Google Earth Pro, the desktop application. For serious detecting research, Google Earth Pro is strongly recommended. It is free to download and provides several capabilities that the browser version lacks, including the ability to import KML and KMZ files (essential for overlaying historic maps), create and save detailed placemarks with notes, measure area and perimeter precisely, and use the historical imagery slider to examine aerial photography dating back to the 1940s in some parts of the UK.
Download Google Earth Pro directly from Google’s website. Installation is straightforward on Windows and Mac. Once installed, take 20 minutes to familiarise yourself with the toolbar, the layers panel on the left, and the ruler tool — these will become your core research instruments.
Organising Your Research Projects
Before hunting a new area, create a dedicated folder in Google Earth’s “My Places” panel for each permission or prospective site. Label it with the county, parish name, and date you started researching. Save all placemarks, polygons, and overlaid maps within that folder. This discipline pays off over time: you build a searchable archive of every site you have researched, including those that came to nothing and those that produced good finds. Many experienced detectorists maintain dozens of these folders and treat them as a professional database of prospective land.
Using Historical Aerial Photography to Find Lost Features
The single most powerful feature in Google Earth for metal detecting research is the historical imagery slider. Access it via View > Historical Imagery, or press Ctrl+H. A timeline bar appears across the top of the screen, allowing you to step through available aerial photographs of any location.
What to Look For in Aerial Photographs
Crop marks are the detectorist’s most valuable aerial indicator. When a buried feature — a ditch, a pit, a wall foundation, a filled hollow — lies beneath a field, it affects the moisture retention and nutrient content of the soil directly above it. During dry summers, crops growing over buried ditches stay green longer and grow taller; those over buried walls or compacted surfaces turn yellow and ripen early. These variations are invisible at ground level but clearly visible from above, particularly in photographs taken during drought conditions.
The summer of 1976 produced some of the most dramatic crop mark photographs in British history, and the dry summers of 2018 and 2022 generated a new wave of discoveries visible in more recent aerial photography. When examining historical imagery in Google Earth, always check images taken in late July and August of particularly dry years. The Cambridge University Collection of Aerial Photography (CUCAP), now held by the Aerial Photographic Archive for Archaeology in the Midlands (APAAME), has documented thousands of crop mark sites across England and Wales that have never been formally excavated — making them legitimate research targets for detectorists with appropriate landowner permission.
Specifically, look for:
- Ring ditches — circular marks indicating Bronze Age burial mounds (barrows) that have been ploughed flat over centuries
- Rectilinear enclosures — rectangular or square outlines indicating Roman farmsteads, Iron Age settlements, or medieval manorial sites
- Linear features — straight lines that may indicate Roman roads, field boundary ditches, or trackways
- Dark soil patches — areas of disturbed or enriched soil that often indicate intensive past occupation
- Ridge and furrow — the characteristic corrugated pattern of medieval open-field agriculture, visible across the Midlands in particular
Reading Plough Soil Shadows
In autumn and winter aerial photography, when fields are bare after harvest or ploughing, look carefully at the colour variation in the soil itself. Darker patches frequently indicate areas of higher organic content associated with prolonged human occupation — midden deposits, collapsed organic structures, or high concentrations of charcoal from hearths. Detectorists who have cross-referenced these dark soil patches with subsequent field walking and detecting have found significant concentrations of Roman and medieval material that would not have been apparent from ground level alone.
Cross-Referencing with Historic Ordnance Survey Maps
Google Earth’s ability to overlay external image files is transformative when combined with historic Ordnance Survey mapping. The National Library of Scotland provides free, georeferenced historic OS maps through its online map viewer at maps.nls.uk, covering Scotland in extraordinary detail and including significant coverage of England and Wales through the six-inch and 25-inch series produced between the 1840s and 1960s.
How to Overlay Historic OS Maps in Google Earth
The National Library of Scotland’s website allows you to export tiles or download KMZ overlay files for specific map series. To use these in Google Earth Pro:
- Navigate to maps.nls.uk and select the relevant historic map series for your area of interest
- Download the KMZ overlay file for your target grid square where available, or use the “Georeferenced maps” export function
- In Google Earth Pro, go to File > Open and load the KMZ file
- Adjust the transparency slider for the overlay layer so that you can simultaneously see the historic map detail and the current satellite imagery beneath it
- Compare the two layers to identify features that once existed but have since been destroyed or buried by subsequent development and agricultural change
The most productive comparison is usually between the first edition OS six-inch survey (surveyed 1840s–1870s across most of England and Wales) and the current satellite view. Features visible on the Victorian mapping that have since disappeared — field boundaries, ponds, trackways, farm buildings, mills, churches — often indicate areas of past human activity that still retain buried material. A farmstead shown on the 1870 OS that is now open agricultural land, for example, represents a highly productive target for a detectorist who has secured the relevant landowner permission.
Moving Forward
Once you have the fundamentals in place, the possibilities open up considerably. The UK offers fantastic opportunities for anyone interested in this hobby, and with the right foundation you will be well placed to make the most of them.
