You will learn
The ground remembers
A site may look empty today, but the ground keeps a record of everything people did on it: every building, tank, pond, quarry and tip. Site history is how you read that record without digging a single hole.
It is often the most revealing part of a desk study, and it is mostly free.
- Explain why a site’s past uses matter for what is in the ground today.
- Find and compare old maps and aerial photographs of a site.
- Turn what you find into a site history timeline and a list of possible hazards.
Why it matters
What past uses leave behind
When a factory closes or a pond is filled in, the evidence rarely leaves the site. It is buried. Here is what past uses commonly leave in the ground:
Made ground
Soil, rubble, ash and waste placed by people. It can be loose, uneven and contaminated.
Old foundations
Buried walls, floor slabs and machine bases that get in the way of new foundations and piles.
Contamination
Fuels, oils, metals and chemicals from industry, garages, tanks and railways.
Filled-in features
Ponds, pits and quarries filled with whatever was to hand. Often soft, and sometimes a source of ground gas.
Old shafts and wells
Openings from mining, wells or old drainage that may have been capped badly, or not at all.
Hidden water
Streams that were diverted or piped underground (culverted), and old drains that still carry water.
The point
You cannot see any of this from the surface. But most of it shows up on old maps and photographs, if you know where to look and what to look for.
The idea, in plain words
Where to find a site’s history
In the UK you can build a good picture of most sites from free sources. Start at the top of this list and work down.
Detailed maps of Britain go back to the 1840s, with new editions every few decades. The National Library of Scotland shows many of them free online, for England, Wales and Scotland, with a side-by-side viewer that lets you compare old and new.
FreeHistoric England’s Aerial Photo Explorer holds over 400,000 aerial photos of England from 1919 onwards. Britain from Above shows the early Aerofilms photos from 1919 to 1953.
FreeGoogle Earth Pro (the free desktop version) has a historical imagery slider. It shows how a site has changed over recent decades.
FreeThe local council’s planning website lists past applications, and older ones sometimes include earlier reports or investigations. Always ask the client too: many sites already have an old investigation report sitting in a file.
FreeOld photographs, trade directories and local history books can tell you who used a building and what they made there.
Free to visitSpecialist companies sell reports that gather historical maps and environmental records for a site in one place. They are widely used on real projects.
PaidPeople are a source too. Neighbours and long-time workers often remember what the maps miss. You will learn to ask them during the site walkover in Lesson 6.
The idea, in plain words
How to read old maps
Reading old maps is a method, not a talent. Follow four steps:
Look at the site and its surroundings, not just inside the boundary. Contamination and ground gas can move, so a works next door matters. Many practitioners use a set distance, such as a few hundred metres, and state it in the report.
Open the earliest map first, then step forward edition by edition. Each map is a snapshot taken years apart.
Note what is on the site and what is around it, with the map date. Keep it short.
The most useful clues are things that appear or disappear. A pond that vanishes between two editions has usually been filled in. A building that appears tells you when a use began.
Words on old maps, and what they can mean
| Words you may see | What it can mean for the ground |
|---|---|
| Works, Mill, Foundry | Old foundations and possible contamination, depending on what was made |
| Tank, Tanks | Stored fuel or chemicals; possible oil or fuel contamination |
| Gas Works | Often serious contamination, such as tars, oils and cyanides |
| Pit, Quarry, Sand Pit, Clay Pit | A hole in the ground, which may later have been filled |
| Tip, Refuse, Spoil Heap | Made ground or waste; possible ground gas |
| Pond, Marsh, Reservoir (later gone) | Filled-in ground, often soft |
| Shaft, Old Shaft, Old Coal Pit | Past mining; possible openings and unstable ground |
| Railway, Sidings | Ash fill, oils and possible weedkillers |
| Garage, Depot, Filling Station | Fuel storage; possible fuel contamination |
Mind the gaps
Map editions can be ten or more years apart, and a whole factory can come and go in between. Use aerial photographs to fill the gaps, and never assume that nothing happened just because two maps look the same.
The idea, in plain words
From clues to possible hazards
History on its own is just a story. The skill is to turn each past use into a possible hazard for the new project. Ask three questions of every use you find:
1. What was it?
The use, where it was, and when. For example: a fuel tank near the northern boundary, about 1925 to 1995.
2. What could it leave?
Fuel and oil in the soil and groundwater, and the buried tank or its base.
3. Why does it matter?
Risk to future residents and to the river, and an obstruction for new foundations.
Write “possible”, not “definite”
A map shows that a tank was there. It does not show that it leaked. A desk study identifies possible hazards; the ground investigation later finds out whether they are real. Saying this clearly is part of writing honestly.
What happens next with each hazard
Every possible hazard you record becomes something the ground investigation has to check. That is why the desk study matters so much:
| Possible hazard in your desk study | What the investigation will need to do |
|---|---|
| Filled-in pond or pit | Put exploratory holes in it to find how deep and how soft the fill is, and monitor for ground gas |
| Former fuel tanks | Test the soil and groundwater around them for fuel and oil |
| Old foundations and machine bases | Dig inspection pits first, and allow time for breaking through obstructions |
| Nearby tip or landfill | Install wells and monitor ground gas over several visits |
| Railway sidings | Test the ash and fill along the old track for contamination |
The surprises that are on no drawing
On industrial and operational sites, buried services and old foundations that appear on no drawing are among the commonest surprises when digging starts. Often the only warning is an old map or aerial photo showing a building or pipe run that has since disappeared. A careful history search is what earns that warning.
On our site
The history of Brindlemere Yard
Remember the cut-away drawing in Lesson 1? Here is where those buried features came from. This is what the maps and photos of our fictional site show.
Brindlemere Yard: Desk Study Report (fictional example)
3. Site history
Historical maps and aerial photographs were reviewed for the site and the area within 250 m of it.
| Date and source | On the site | Around the site |
|---|---|---|
| About 1880, map | Fields. A pond in the south-east corner | River Brindle to the east. A corn mill 200 m north |
| About 1905, map | Brindlemere Iron Works across most of the site. The pond remains | Housing to the west |
| About 1925, map | Works extended. Pond no longer shown. A tank near the northern boundary | No significant change |
| About 1955, map | Works, with two tanks. Railway sidings along the western boundary | Refuse tip 150 m to the south |
| About 1975, map | Now labelled Engineering Works. More buildings | Garage across the road to the north |
| About 1995, map | Buildings labelled disused | Refuse tip no longer shown; area grassed |
| 2005, aerial photo | Buildings demolished. Concrete slabs and rubble heaps | No significant change |
| 2024, satellite image | Vacant. Hardstanding and scrub | No significant change |
Possible hazards from the site’s history:
- Made ground, including demolition rubble, across the site.
- Buried foundations and machine bases from the works.
- Fuel and oil contamination around the former tanks, and from the garage to the north.
- Metals and other contamination from iron working and engineering.
- Soft ground, and possible ground gas, in the filled-in pond (between about 1905 and 1925).
- Ash and oils along the former railway sidings.
- Possible ground gas from the former refuse tip 150 m to the south.
Notice the pond
The pond is on the 1905 map and gone by 1925. Nobody wrote down that it was filled. The two maps, side by side, tell you.
Your turn
Build your site’s timeline
Wherever you are
Most countries have old maps and aerial photographs somewhere. Try:
- Google Earth Pro’s historical imagery, which covers the whole world, though how far back it goes varies by place.
- Your national mapping agency, national library or national archive, which often hold old maps and aerial survey photos.
- University map libraries and local archives.
- People who know the area: long-time residents, landowners and local officials.
If you cannot find early records, say so in your report. A gap is information too, and it means the site walkover and later investigation need to work harder.
Task (20 minutes)
For your own site, find at least three dates: one old map, one aerial photo, and one recent image. Then fill in a table like ours:
| Date and source | On the site | Around the site | Possible hazard |
|---|---|---|---|
Finish with a short list of possible hazards, written as “possible”, not “definite”.
Quick check
Five quick questions
This is not a test. It simply shows you whether you are ready for Lesson 4. Choose an answer to see the explanation.
Key points
What to take away
- Past uses leave made ground, old foundations, contamination, filled-in features, shafts and hidden water.
- In the UK, old maps go back to the 1840s, and old aerial photos to 1919. Many are free online.
- Read maps from oldest to newest, look around the site as well as on it, and watch for things that appear or disappear.
- Turn each past use into a possible hazard: what was it, what could it leave, why does it matter?
- Write “possible”, not “definite”, and say clearly where records are missing.
Where to look (free)
- Historical Ordnance Survey maps (National Library of Scotland)
- Aerial Photo Explorer (Historic England)
- Britain from Above (aerial photos 1919 to 1953)
- Google Earth Pro (historical imagery, worldwide)
Up next: Lesson 4
Ground and water. What the ground is made of, where the groundwater is, and whether the site floods.