Calibration Data

File Formats

The program is supplied with data files for Intcal04 which are identical to those for the CALIB program. The three data files include in this distribution are:
IntCal04.14cAtmospheric data for the N HemisphereReimer et al 2004
Marine04.14cMarine data (requires local correction)Hughen et al 2004
ShCal04.14cAtmospheric data for the S HemisphereMcCormac et al 2004

The default curve is the atmospheric N hemisphere curve intcal04.14c.

Previous versions of the calibration curve are also included: cal_86.dta (was called cal10.dta in older versions), cal_93.dta (was cal20.dta) and intcal98.14c

A post-bomb compilation is also included in kueppers04.14c see Kueppers et al 2004 for details. Because of the very fast rise in radiocarbon over this period a resolution of 0.1 years may work best - or consider whether a reservoir time constant should be applied - even if only of 1-2 years as this can make a significant difference.

This program will work with any data files intended for the CALIB (*.14c) or the Groningen program (*.dta).

The current IntCal datasets are based on a BP timescale and are comma delimited. This is recognised by the program by the presence of the CAL BP label in the header. The comment lines are started with a # and the comment included as a short reference starts with ##. The format is:

CAL BP, 14C age,Error,Delta 14C,Sigma
Previous versions of CALIB used a data format with five columns of numbers:
Calendar_date     Delta_14C     error     14C_Age       error
whereas the Groningen program uses a basic file format of:
Calendar_date     14C_Age       error
The program automatically detects the format. In addition to the calibration curve data itself the files can also be modified to provide the reference data on the top of the plots. Lines starting with the character "  or the string  ## are combined together to form the reference string.

Lines not starting with the reference character or which do not contain data in the right format are ignored.

Changing Calibration Curves

To use different calibration curves within the same plot use the command Curve. This is done by dragging the relevant icon from the right hand window when building a model. Note that multiple plots on the calibration curve always use the default curve.

For environments with a reservoir effect a special curve can be generated using Reservoir. Samples from the oceans should use a specific marine curve and Delta_R corrections.

In the Southern Hemisphere the ShCal.14c curve should be used.

See [Mathematical Methods]

Marine Curves and Corrections

A calibration curve modeled for the oceans (see Hughen et al 2004) is supplied and is called marine04.14c. This can be offset for local variations using Delta_R corrections (see Stuiver and Braziunas 1993) which are available online from Queen's University Belfast.

See [Mathematical Methods]

Mixed Calibration Curves

These can be included using a combination of the Curve and Mix_Curves statements. A typical application where there was a 205% marine component would include the statements:

 Curve "intcal04" "C:\Program Files\OxCal3\intcal04.14c";
 Curve "local_marine" "C:\Program Files\OxCal3\marine04.14c"; Delta_R 100 30;
 Mix_Curves "mixed" "intcal04" "local_marine" 20 5; 
 R_Date 660 35;
See [Mathematical Methods]

Default Calibration Curve

If you wish to change the default calibration curve file you should: