"terminus post quem" and "terminus ante quem"

[Giacomo Capuzzo]

Hi all,

 

I am running an easy chronological model composed of one phase dating the use of structure 1A. I have additional information regarding the beginning and the end of the phase provided by two dates with the values of “terminus post quem“ and “terminus ante quem”, respectively.

 

Terminus post quem for the Boundary Start: R_Date("X-9", 640, 35);

Terminus ante quem for the Boundary End: R_Date("X-10", 379, 31);

 

I think the right tools are “After” and “Before”, but I have doubts regarding their position in the code.

I would be grateful if you can help me with that.

 

Best,

Giacomo

 

Options()

 {

  Curve="SHCal13.14c";

 };

 Plot()

 {

  Phase("Structure 1")

  {

   Sequence(Structure 1A)

   {

    Boundary("Start Structure 1A");

    Phase("Structure 1A")

    {

     R_Date("X-1", 610, 40);

     R_Date("X-2", 560, 75);

     R_Date("X-3", 550, 50);

     R_Date("X-4", 510, 35);

     R_Date("X-5", 450, 30);

     R_Date("X-6", 445, 30);

     R_Date("X-7", 400, 40);

     R_Date("X-8", 345, 30);

    };

    Boundary("End Structure 1A");

   };

  };

 };

[Jonathan Hanna]

Hi Giacomo,

I'm not sure if there is a technical reason to do one or the other, but in practice I don't believe it matters whether you use Before/After here or not. Since this is a sequence already, if you simply put X-9 before the "Start" boundary and X-10 after the "End" one, it would do the same thing as adding the extra "After" (TPQ) parameter to X-9 and the "Before" (TAQ) one to X-10. But here it is with those:

Plot()

 {

  Phase("Structure 1")

  {

   Sequence(Structure 1A)

   {

    After(R_Date("X-9", 640, 35));

    Boundary("Start Structure 1A");

    Phase("Structure 1A")

    {

     R_Date("X-1", 610, 40);

     R_Date("X-2", 560, 75);

     R_Date("X-3", 550, 50);

     R_Date("X-4", 510, 35);

     R_Date("X-5", 450, 30);

     R_Date("X-6", 445, 30);

     R_Date("X-7", 400, 40);

     R_Date("X-8", 345, 30);

    };

    Boundary("End Structure 1A");

    Before(R_Date("X-10", 379, 31));

   };

  };

 };

Cheers,

-Jon Hanna

[Giacomo Capuzzo]

Many thanks Jon for your fast reply! It's very useful.

Greetings,

Giacomo

[MILLARD, ANDREW R.]

Jon is correct to say that here it makes no difference. Before and After are only necessary if there are other elements of the model where the stratigraphic relationship is not a temporal relationship. The most common reason to use After is when the sample’s date is clearly earlier than its context. The classic example is a coin or heirloom in a grave, which tells you a TPQ for that grave but nothing about a stratigraphically earlier grave.

 

Best wishes

Andrew

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Associate Professor of Archaeology,

Durham University, UK

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[Giacomo Capuzzo]

Thank you for the clarification Andrew. I saw that in my model the TAQ date, "Before" tool, slightly narrows down the probability interval of the Boundary End.

Best,

Giacomo

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