UK GIS layers and Roman map data

For the last week or so I have been experimenting with something old and something new: GIS.

In particular, since I have finally given in and bought a laptop capable of handling complex tasks without freezing, I’ve installed ArcMap. This is a piece of Geographical Information Systems (GIS) software produced by ESRI, which is hideously expensive but, along with its main competitor MapInfo, is the industry standard software for producing anything from simple maps to statistical analyses of complex 3D geographical models. My copy is licensed through UCL, but if you don’t have a institution to pay for such things, I’ve been told that QuantumGIS is both free and  a pretty good alternative.

I’ve used GIS software before, at both of my HER/SMR jobs, but that was limited to popping new points on the map and adjusting the position and shape of things other people had mapped. This last week I have been creating maps from scratch for the first time.

I have to admit, I have enjoyed almost every minute of it. Maps are amazing, and being able to create maps specifically for your research is a powerful tool. It’s hard to express how exciting it is to have all your data pop up on the screen, and to be able to overlay that data on underlying patterns such as previously discovered sites, army sites, topography, bedrock geology, roads… it’s just fantastic.

So fantastic, I haven’t managed to produce my ideal maps yet. The major problem has been finding suitable data to import into my map; after all, there’s no point duplicating the great work done by lots of other people to create, for instance, Roman road maps. GIS works with ‘layers’, in the same way that Photoshop etc do, only these layers are geographically referenced. So I’ve been scouring the web for layers to use, and of course I’ve faced lots of challenges with importing different file types (looking at you, Ordnance Survey!), and setting the map up using the right projection (basically the coordinate system – turns out things look a lot nicer if you pretend the world is flat but that needs conversions…).

I could spend a lot of time talking about all the challenges and the things I’ve learnt, but as I’m still in the process I thought I’d just share a number of good sources for map data. The list is entirely biased towards Roman map layers and the UK, but that’s what I’m focussed on right now. Doubtless I’ll have to tackle Austrian maps soon, but in the meantime…

UK maps:

• DiGMapGB: the Digital Geological Map of Great Britain, this set of data is available from the British Geological Survey, and includes both bedrock and superficial deposits. It is free to download for commercial, research and public use, though you have to acknowledge use.
• Mineral data: the British Geological Survey also has a lot of mineral data, as well as a patchy map of pits, mines and quarries in the UK. Unfortunately none of this data is free, as far as I can ascertain.
• Edina Digimap: only good for students/staff at academic institutions, this site will give you (sometimes limited) access to a massive amount of data. Historic maps (i.e., the early UK maps), Geology maps (from the British Geological Survey, but in an easy-to-access way), and Modern maps including boundaries (often in irritating formats that need conversion or cause headaches). They also make you register individually, which is a bit of a pain, but this is the definitely the place to go.

Roman maps:

• Pleiades: If you are feelingextremely brave and technical, Pleiades produce a CSV file (text) every day with the raw dump of their data. This contains a lot of mapped sites, so you could try importing that. I haven’t! They also produce a KML file every day, but as this seems to requirescript (erk!) to convert this to a file I can use in ArcMap I haven’t tried this (yet). However, I suspect this is the best quality and density of information for Roman sites.
• Ancient World Mapping Centre: The data here is great, and easily accessible in .shp format (for us ArcMap users!).
• Digital Atlas of Roman and Medieval Civilisations: this rather retro looking site is in fact the place holder for some good quality data. You need to open ArcMap and connect to their map servers to download the data, but the DARMC website walks you through it easily enough.

All the Roman data is free, using a CC licence of one form or another. You do have to hand it to the digital classicists, they do work hard and produce some great data!

Edit: And if you’re interested in other historical map data, including for the US, check out this handy list of map data at Historical GIS and Clearinghouse Forum.