ASK THE ARCHAEOLOGIST:

The answers to the most frequently asked questions about archaeology

Dave Weldrake
Education ad Outreach Coordinator

Question 1: How do you know where to dig?

It's down basically to research. Some of it comes from information from antiquarian books. Some of it comes from reading other people's fieldwork reports. Sites can survive as ruins or covered in earth (archaeologists cal these earthworks).Yet more information comes from members of the public, especially through metal detector users reporting finds to the Portable Antiquities Scheme. (For further details of the Portable Antiquities Scheme, please contact the Finds Liaison Officer on 01924 305359) or email acooper@wyjs.org.uk).

However, the most common way of finding new sites, is from the air. It may seem strange but sometimes when you are on the ground you're just too close to see what's under your feet. Growing crops mature differently depending what's underneath them. These differences, called cropmarks, can highlight the positions of buried walls and ditches. Aerial photographs can show you the details of whole structures such as the layout of a park or the position of a castle's defences.

There are a number of aerial photographs on the WYAAS website which you could share with your class. There are links to some of them given in the activity section below.

There are hundreds more aerial photographs of archaeological sites stored in the West Yorkshire Historic Environment Record, where they can be consulted by anyone interested in researching their locality. Space is limited, so you'll need to make an appointment first by emailing us on wyher@wyjs.org.uk or by phoning 01924 306797.

Activity; Looking at aerial photographs
There are lots of aerial photographs on-line on the WYAAS website. Here are links to just some of them.

Almondbury: Castle Hill from the Air

Sandal Castle

Ackton: Cropmarks of Iron Age/Romano-British farm

Two things to try:

Castles Discuss the aerial photographs of the Castles with your class. Possible approaches to the topic might include:
1. Talk about what's on the photograph. Is it easy to work out what's there? Ask them to describe what they see. Place the aerial photograph in the middle of a sheet of clean paper and ask them to label it.
2. Ask them to think about the function of the two sites as castles. Way are the high up? Why do they have deep ditches?
3. Ask the class to consider whether the information would be easier to 'read' if they had maps of the site. Ask them to consider what they would put onto a map and what they would leave out. Get them to draw their map.
Using the aerial photograph of Ackton, explain that the green lines on the photo are like a 'map' of what this area looked like before the Romans arrived. The dark lines represent ditches which are now filled in. Because crops can grow longer roots and there is more moisture in these areas, the crops ripen later and stand taller - hence the formation of the cropmarks. Ask your class to draw what they think the landscape would have looked like. You can compare the results with our Artist's reconstruction of a Romano-British Farmstead.

Useful websites
Hunt the Ancestor is an interactive guide to archaeology from the BBC. It starts with how to identify your site through aerial photography.

Aerial photography techniques are explained in details by Dr. Dave Macleod on this fascinating web site from the BBC.

Google Earth can provide high resolution aerial images of many parts of the UK. Free downloads are available for personal use, but a licence is necessary for commercial purposes.