Stratigraphy!

Here I present the stratigraphic (Harris) matrix for the test-pit, the bane of many an archaeologist's life, but too useful a tool to ignore.  I will attempt to explain to the lay person as concisely as possible, but I fear I may not be up to the job really.  I won't hold it against you if you abandon this blog post now.

Anyway, here goes... a matrix is a graphical representation of the sequence of the deposits that we found in the archaeological test-pit.  Each number represents a single context or event.  Most 'events' are the deposition of layers of soil, however 'events' such as the digging of the animal grave and the foundation slot are also given context numbers, to distinguish them from the filling-in 'events' of those features.  Deposits (or events/contexts) lower down on the matrix are earlier than deposits higher up.  Deposits shown on the same level probably occurred at roughly the same time , but may not have, and the sequence of deposits doesn't give any clues about which is earlier or later.

This stratigraphic matrix is a relatively simple one, but the same system is used for much larger and complex archaeological sites.  Once this has been constructed the information about the dates of the finds from each deposit/context is added.  With these two sources of information we can construct a general sequence of events for the site.  

It is also a good way to test some ideas and interpretations about the deposits.  For example, while the animal grave was being dug I thought that it might date from the 18th Century or earlier since it pre-dated the 19th Century garden and looked like it might relate to the farm in the vicinity.  No datable finds came from the grave to indicate when it was dug, however my 18th Century interpretation must be wrong, because we can see two layers pre-dating the grave both contained 19th Century pottery types.  Put simply, unless we are to believe in time-machines, something can't be put in the ground BEFORE it is invented.

Some events in this matrix probably took place very quickly, for example the animal grave 106/105 was probably dug and filled in within a very short space of time.  Other events, on the other hand, took place over a long time: deposit 109 probably formed over millenia by a continuous process of soil eroding down the hillside and intermittently being mixed up by ploughing.  This deposit contained only a single small fragment of Roman tile, which doesn't help much when trying to determine how long the deposit took to be laid down.

The next stage of the analytical process involves constructing an interpretive narrative that incorporates all the strands of information that we have discovered.  In other words we write a nice story...