We will also extend our three-sample reference from Bergvik to the time of today. For this we will use measurements from a 240 year old Scotch pine where the core sample was taken in 1995 and there is bark left at the top of the sample. This sample is named NM051.pos
1. First open the NM051.pos coordinate file.
2. Click the Workbench tab and then "Set date of youngest ring" and enter 1995 into the year field as shown in the picture above. Click ok!
3. Then select Samples/Save coordinate data to save the file.
4. Then click on the button "Select as reference".
2. Click on the button "Create mean value sample".
3. Click the Workbench tab and then the button "Clear report".
4. Uncheck "Sample may be younger than the reference" to avoid nonsense datings.
5. Click on "Make a whole sample correlation analysis".
6. Set the block length to 75 years.
7. Click on "Make block correlation analysis".
From the first correlation analysis you can see that there are two competing datings, one at relative year 120 and one at 198, though that of 198 is only based on 40 years covering each other.
Note: The results of your own correlation analysis may not look exactly as that above. The cause is probably that you have another setting for "Least overlap in years between samples when correlating" in Settings/Options for normalization of ring widths and for matching.
From the block correlation analysis you can see that the first 75 years of the NMBS1_5_8 match very well towards relative year 120 in the the reference NM051.pos.
8. Click on "Correlate single block"! - Here is the result:
--Rel Corr Over TTest (year)
-year coef lap
120 0.58 75 6.1 (1875)
198 0.36 40 2.4 (1797)
50 0.25 75 2.2 (1945)
175 0.26 63 2.1 (1820)
53 0.24 75 2.1 (1942)
103 0.22 75 1.9 (1892)
47 0.21 75 1.8 (1948)
62 0.21 75 1.8
70 0.21 75 1.8
That calculation convinced CDendro that this mean value sample can be dated to 1875 so the button "Set date of youngest ring" now
says "Proposed year 1875"!
As we are not going to save this dated mean value sample, we will instead go back and put the dating into our collection file!
2. Click on the button Set date of youngest ring
3. Enter the year 1875 and click on OK.
4. Select the menu command Collections/Save collection
A last exercise:
1. Create a new empty collection.
2. Click the button "Set date of youngest ring", and set the year to 1995.
3. Open the NM051.pos file and add it to this collection at offset zero.
4. Switch to the NMBS1_5_8.fil collection
5. Select the menu-command Collections/Copy collection members to target collection
6. In the pop-up window, see that "Always use collection dating and member's offset" is selected, and click OK.
7. Switch to the target collection and save it as fourfiles.fil (Collections/Save collection As)
The collection window should then look as shown above.