How to define the time span occupation of a site

[Patricio De Souza]

Hi to all. I have the following problem: I'm looking to define the span of occupation of a single site. I have more than one excavation unit (A and B), plus two events without clear stratigraphic relationships to the others (and the end of the script). However, the span function yields a median value of nearly 700 years, which is significantly longer than expected. 

What am I doing wrong?

Thanks in advance for your help !!!

Plot()
 {Phase ("Confluencia-2")
   {
    Sequence ("A")
    {
     Boundary ("Inicio A");
     R_Date("Confluencia-2",5883,35);
     R_Date("Confluencia-2",5921,32);
     Boundary ("Final A");
    };
    Sequence ("B")
    {
     Boundary ("Inicio B");
     R_Date("Confluencia-2",6050,29);
     R_Date("Confluencia-2",5861,33);
     Boundary ("Final B");
    };
    R_Date("Confluencia-2",5913,34);
    R_Date("Confluencia-2",5962,32);
    Span ();

   };
 };

[MILLARD, ANDREW R.]

Dear Patricio,

 

You need to have overall boundaries for the site as in the model below, which gives a duration of 30-220 at 95% probability with median 150 years.

 

It’s advisable not to repeat names within the model, so I appended letters to distinguish the dates.

 

 

Plot()
 {Sequence(){

Boundary ("Start Confluencia-2");

Phase ("Confluencia-2")
   {
    Sequence ("A")
    {
     Boundary ("Inicio A");

     R_Date("Confluencia-2a",5883,35);
     R_Date("Confluencia-2b",5921,32);

     Boundary ("Final A");
    };
    Sequence ("B")
    {
     Boundary ("Inicio B");

     R_Date("Confluencia-2c",6050,29);
     R_Date("Confluencia-2d",5861,33);

     Boundary ("Final B");
    };

    R_Date("Confluencia-2e",5913,34);
    R_Date("Confluencia-2f",5962,32);
    Span ();

   };
Boundary ("End Confluencia-2");

};

 };

 

 

Best wishes 

Andrew 

-- 

Prof. Andrew Millard 

Department of Archaeology,

Durham University, UK 

Email: A.R.M...@durham.ac.uk  

Personal page: https://www.durham.ac.uk/staff/a-r-millard/ 

Dunbar 1650 MOOC: https://www.futurelearn.com/courses/battle-of-dunbar-1650 

Durham research: http://www.durham.ac.uk/global-research-brochure

 

 

From: ox...@googlegroups.com <ox...@googlegroups.com> On Behalf Of Patricio De Souza
Sent: 30 October 2025 10:38
To: OxCal <ox...@googlegroups.com>
Subject: How to define the time span occupation of a site

 

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[Patricio De Souza]

Thanks a lot, Andrew. You really helped me!