Tuesday, 26 March 2013

A Murder of Crows

Today I made a flying visit to English Heritage's office in York to see the Regional Science Advisor and my good friend, Dr. Andy Hammon.  Before becoming a faceless bureaucrat Andy was once an archaeo-zoologist, so I hoped he'd be able to identify the bird type in the animal grave.

As a reminder, here is the bone assemblage recovered from pit fill (105).  Only about half of the small pit was within the test-pit, so we recovered only a partial assemblage.

It was fortuitous that on the day that I visited Andy, his colleague Dr. Eva Fairnell was in the process of cataloguing a collection of animal and bird skeletons and we had a lot of reference skeletons to hand.  My prediction that it was a pit full of pigeons was quickly demolished when Andy identified the bones as belonging to Corvids, with a single rogue amphibian bone in the mix.  The family Corvidae includes, rooks, crows, jackdaws, magpies and jays. The reference collection helped us narrow the bones down further to rooks/crows or jackdaws. Also, the bones were all from individuals that were not quite fully grown ("sub-adult").  Here is Andy's catalogue of the bones.

Juvenile jackdaw/rook/crow

MNI = 4

4 x left carpometacarpus
1 x right carpometacarpus
4 x left tarsometatarsus
2 x right tarsometatarsus
1 x right ulna
1 x left ulna
1 x pelvis
Assorted cranial and mandible fragments

1 x amphibian femur

Interestingly, one of my suspicions about the group was confirmed: there was more than one bird in the pit.  MNI = 4 refers to the "Minimum Number of Individuals" present in the assemblage.  In this case there were 4 left carpometacarpus or wing bones, meaning that there were at least four birds in the pit.

So, how to interpret four crows in a pit?  Three possible interpretations spring to mind: 1) A pet burial 2) Food disposal 2) Vermin disposal

1) Pet burial - These features are common in the back gardens of houses from the 19th to 21st Centuries.  I suspect that most readers will have planted at least one beloved pet in their back garden, myself included (sadly, these are quite often disturbed by archaeologists).  Crows, rooks, and especially jackdaws were often kept as pets, however I find it difficult to believe that four such pets would die and be buried at the same time.  Also, the stratigraphic sequence suggests that this pit probably pre-dated the construction of the row of townhouses along Acomb Road, so it was not dug in a backgarden at all.  More likely, in the mid 19th Century, this was a bit of agricultural land or open ground outside the core of Holgate village. 

2) Food disposal - The American euphemism for humiliation notwithstanding, crows were sometimes eaten even into the 20th century, and apparently remain a delicacy in Lithuania to this day.  This reminds me of the nursery rhyme containing the line "Four and twenty blackbirds baked in a pie"Sometimes clear evidence for butchery can be found on animal bones, or the assemblage can consist of the choicest cuts of meat.  Neither is true of this assemblage.  In fact, the bones present in the pit were predominantly the upper parts of the skeleton, and we may presume that the un-excavated half of the pit contained the lower portions.  The suggestion is that the birds were buried whole and therefore not the remains of a meal.

3) Vermin disposal - Corvids can be opportunistic predators and scavengers and may well have been considered vermin by the agricultural/horticultural workers in the vicinity, and disposed of when the opportunity arose.  The fact that the crows were all sub-adult and disposed of together possibly supports this.  

I think on balance, that a brood of young crows was killed as vermin and disposed of in the pit at a time when the land was in agricultural use.  Not long afterwards, in the late 19th Century, the village of Holgate expanded across the site and I can only presume that this probably commonplace rural practice was replaced by a more urban sensitivity that most of us would be familiar with today.  

I should point out that I really like crows.


Monday, 25 March 2013

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...

Thursday, 21 March 2013

Welcome home...

Catriona has kindly gifted us one of her jars. Here it will live for another 150 years!