Radiometric Measures

Calibration Programs Contd.,

Calib 4.1

Calib 4.1 can be downloaded from the University of Washington 's Quaternary Isotope lab. The program is self extracting to Microsoft MS-DOS where it runs on a menu driven basis. It can also run on Mac machines on OS 7.5 - 8.0. It crashes at OS 8.5. Run on Windows by double clicking on 'calib.exe' file. Immediately you'll get the Main menu below :

Other sub menus are embedded within this menu. Calib is now up to Ver 4.4 at this writing. It's very much more user involved than the Oxcal program. There are many steps to get a listing or graph done so let's take it piece by piece. Firstly, Key in 2 from the above menu, this takes you to the Calculations Options Menu as seen below:==

Unflag the letter A on your keyboard by pressing it

Flag B

Flag D , (the error multiplier K)

DO NOT flag H (Fractionation is already accounted for in a CRA)

Flag I to sample code or toggle it

Flag L

Flag M

Flag N

Flag O

Flag P (optional)

Flag S

Leave all others alone

Hit the letter R to return to main menu

Key number 3 (Data I/O Menu)

Select and key in number 1 (enter sample data from keyboard)

A 'enter lab code ' message will appear

Key in 1 and hit return key

A 'enter sample code' appears hit 1 and hit return key

Hit return key again and the CALIBRATION CURVE OPTIONS menu appears as below

Make sure 'A' is flagged i.e. Dataset 2 1998 Atmospheric Decadal dataset

Hit Return key

Now you can enter the Radiocarbon age which is a 4 figure number in this example 6835

Hit return key

'Enter Standard Deviation in Age' ,this is the so called error term e.g. 110 hit 'R' or return

'Enter Lab Error' , key in ' 1 ' hit return key

If you want to save samples to file key in 'Y' or 'N'

Finally key in ' XX ' to end .Hitting return will take you to the DATA I/O MENU

Hit 'R' letter to get to MAIN MENU

Key in ' 5' Calibrate and the screen will show your results in both Sigma 1 and 2 as below

When you are finished with this screen, hit 'R' to return to main menu

In the Main Menu 'Preliminary Setup' key in ' 7 ' for plotting graphs, you should see the PLOTS OPTIONS MENU below

Key ' 1' then flag ' B '

Key ' 2 ' then flag ' D ' or ' G '

Key '3 ' then flag ' B ' and ' U '

Finally key ' 8 ' for a plot graph to appear as below

There are many other options to numerous to mention in this introduction so I'll leave that to the user to explore themselves. These two programs should give relatively the same results because the calibration program itself is intcal98c(Pearson & Stuviers 1998) in both. Next I have a series of Conventional Radiocarbon Ages ( CRAs in BP) from Irish megalithic sites .
Irish Radiocarbon Ages in BP

KNOWTH, BOYNE VALLEY

These are in classic conventional presentation terms (CRAs)

Knowth 1, GrN 12357. 4405 +/- 35 BP (c. 2455 +/- 35 bc)

Knowth 1, GrN 12358. 4490 +/- 60 BP (c. 2540 +/- 60 bc)

Knowth 1, GrN 12827. 4465 +/- 40 BP (c. 2515 +/- 40 bc)

Knowth 1, U B 00357. 4745 +/- 165 BP (c. 2795 +/- 165 bc)

Knowth 1, U B 00358. 6835 +/- 110 BP (c. 4885 +/- 110 bc)

Knowth 2, B M 00785. 4158 +/- 126 BP (c. 2205 +/- 126 bc)

Knowth 9, GrN (prov.). 4415 +/- 50 BP (c. 2465 +/- 50 bc)

Knowth 16, B M 01078. 4399 +/- 67 BP (c. 2449 +/- 67 bc)

CARROWMORE, CO. SLIGO

Carrowmore Site 4, Lu - 1840. 5750 +/- 85 BP ( 3800 +/- 85 bc)

Carrowmore Site 4, Lu - 1750. 4320 +/- 75 BP (2370 +/- 75 bc)

Carrowmore Site 7, Lu - 1441. 5240 +/- 80 BP (3290 +/- 80 bc)

Carrowmore Site 27, Lu - 1698. 5040 +/- 60 BP (3090 +/- 60 bc)

Carrowmore Site 27, Lu - 1808. 5000 +/- 65 BP (3050 +/- 65 bc)

Carrowmore Site 27, Lu - 1818. 4940 +/- 85 BP (2990 +/- 85 bc)

Copyright George Eogan, 'Knowth and passage-tombs of Ireland, Thames & Hudson, London 1986, Appendix.

NEWGRANGE, BOYNE VALLEY

***Newgrange 1, GrN - 5462-C 4425 +/- 45 BP (c. 2475 +/- 45 bc)

***Newgrange 1, GrN - 5463 . 4415 +/- 40 BP (c. 2465 +/- 40 bc)

Newgrange 1, GrN - 6342. 3885 +/- 35 BP (c. 1935 +/- 35 bc)

Newgrange 1, GrN - 6343. 3990 +/- 40 BP (c. 2040 +/- 40 bc)

Newgrange 1, GrN - 6344. 4050 +/- 40 BP (c. 2100 +/- 40 bc)

Newgrange 1, GrN - 9057. 4480 +/- 60 BP (c. 2040 +/- 60 bc)

Newgrange 1, UB - 361. 4535 +/- 105 BP (c. 2585 +/- 105 bc)

Newgrange 1, UB - 360. 2250 +/- 45 BP (c. 0300 +/- 45 ad)

Newgrange 1, UB - 2392. 3985 +/- 55 BP (c. 2035 +/- 55 bc)

Newgrange 1, UB - 2393. 4535 +/- 45 BP (c. 2035 +/- 45 bc)

Newgrange 1, UB - 2394. 3875 +/- 60 BP (c. 1925 +/- 90 bc)

Copyright C O'Kelly, 'Newgrange, Archaeology, Art & Legend,' Thames & Hudson, London,1982,Appendix H

I have placed a set of asterisks before the first two radiocarbon ages , that's because the late Prof. O' Kelly maintained these two samples gave a construction date for the site. In all cases of being presented with these kind of multiple ages as above its best to pick the ages (CRAs) that have the lowest error term values (S.D 1) that way you can scale up the confidence levels without incurring too wide a probabilistic range of calibrated dates. Remember all calibration results are probabilistic , they do not give a specific calibrated date per se but a range from which you can pick a date.

Bibliography / Webography

1. Bowman, Sheridan, 'Interpreting the Past; Radiocarbon Dating, University of California Press, Los Angeles, 1990

2. Eogan, George, 'Knowth & other passage-tombs of Ireland, Thames & Hudson, London,1986

3. O'Kelly, Michael, 'Newgrange;Archaeology, Art & Legend, Thames & Hudson, London, 1982

4.www.c14dating.com/int.html

5.www.c14dating.com/agecalc.html

6.www.gns.cri.nz/atom/rafter/glossary.htm

7.http://depts.washington.edu/qil/calib/manual/chapter1.html