After boring the drill core is kept in wooden boxes that host 4 to 10 meters of core depending on the diameter. There are about 30 000 drill core boxes preserved in Estonia. Material owned by the state are stored at four different locations (see Figures 2-11). By the order of the state, Geological Survey of Estonia fixed up about 1000 boxes every year (meaning re-labelling, fixing and photographing). Information and photos of the drill cores are saved in the database. This database contains also data used for compiling the Geological Base Map of Estonia. For 2015, all the drill core boxes have been fixed. The next task is to put drill core samples in order. Data of the samples and photos of the representative specimens are also saved in the Borehole database.
An example of a drill core box (drill core no F259; from interval 136,8...141,0 m).
In 2004, 1436 boxes from 52 drill cores were ordered for long-term preservation (Figure 1).
Figure 1. Locations (yellow squares) and amount of drill core boxes in January 2005. Red dots indicate locations of the drillholes the cores of which were checked for their condition in 2004.
In 2005, the cores (1767 boxes) previously preserved in the former Piirsalu rocket base were transported to Keila, 458 of these were sorted out. At the same time 458 core boxes were ordered in the Arbavere depository (Figure 2).
Figure 2. Locations (squares) and amount of drill core boxes in January 2006. The dots indicate locations of the drillholes the cores of which were checked for their condition in 2005. Color of the dot indicates the location where the appropriate drill core box is stored.
In 2006, 501 boxes were ordered in Keila and 1017 boxes in Arbavere (Figure 3).
Figure 3. Locations (squares) and amount of drill core boxes in January 2007. The dots indicate locations of the drillholes the cores of which were checked for their condition in 2006. Color of the dot indicates the location where the appropriate drill core box is stored.
In 2007, 311 boxes from 27 drill cores were transported from Piirsalu to Keila and ordered along with the 1308 boxes from the 97 cores in Arbavere (Figure 4).
Figure 4. Locations (squares) and amount of drill core boxes in January 2008. The dots indicate locations of the drillholes the cores of which were checked for their condition in 2007. Color of the dot indicates the location where the appropriate drill core box is stored.
In 2008, 544 core boxes were ordered in Keila (230 of these originated from Piirsalu and 314 from Tuula depository) and 460 boxes in Arbavere. Altogeher 88 mainly partial core sections were ordered (Figure 5).
Figure 5. Locations (squares) and amount of drill core boxes in January 2009. The dots indicate locations of the drillholes the cores of which were checked for their condition in 2008. Color of the dot indicates the location where the appropriate drill core box is stored.
In 2009, 499 core boxes representing 67 drill cores were sorted out and photographed in Tuula as well as 403 boxes in Arbavere (Figure 6).
Figure 6. Locations (squares) and amount of drill core boxes in January 2010. The dots indicate locations of the drillholes the cores of which were checked for their condition in 2009. Color of the dot indicates the location where the appropriate drill core box is stored.
In 2010, 918 core boxes representing 90 drillcores were ordered and photographed in Tuula depository (Figure 7).
Figure 7. Small rings indicate locations of the drillholes the cores of which were checked for their condition in 2010. Big red dots mark repositories where the drill core boxes are stored (with total amount of boxes written in brackets). All drill core boxes (918) fixed up in 2010 are situated in Tuula repository.
In 2011, 575 core boxes from 48 drill cores were ordered and photographed in Tuula (Figure 8).
Figure 8. Small rings indicate locations of the drillholes the cores of which were checked for their condition in 2011. Big red dots mark repositories where the drill core boxes are stored (with total amount of boxes written in brackets). All drill core boxes (575) fixed up in 2011 are situated in Tuula repository.
In 2012, 409 core boxes representing 55 drill cores were ordered and photographed in Tuula. 604 boxes considered as irrelevant for further preservation were disassembled (Figure 9).
Figure 9. Small rings indicate locations of the drillholes the cores of which were checked for their condition in 2012. Big red dots mark repositories where the drill core boxes are stored (with total amount of boxes written in brackets). All drill core boxes (409) fixed up in 2012 are situated in Tuula repository.
In 2013, 200 core boxes were ordered in Tuula as well as 201 boxes in Turja depository, acquired from 46 and 10 drill cores, respectively. 600 boxes considered as irrelevant for further preservation were disassembled (Figure 10).
Figure 10. Small rings indicate locations of the drillholes the cores of which were checked for their condition in 2013. Big red dots mark repositories where the drill core boxes are stored (with total amount of boxes written in brackets).
In 2014, 100 core boxes were ordered in Tuula and 554 boxes in Turja depository, acquired from 26 and 35 drillcores, respectively. 84 boxes considered as irrelevant for further preservation were disassembled and removed from the Turja depository (Figure 11).
Figure 11. Small rings indicate locations of the drillholes the cores of which were checked for their condition in 2014. Big red dots mark repositories where the drill core boxes are stored (with total amount of boxes written in brackets).
In 2015, 5108 samples collected from the crystalline basement drill cores were sorted out.
In 2016, 4144 samples collected from different drill cores and fieldworks were sorted out.
In 2017, 3683 samples collected mainly from the sedimantary bedrock intervals were sorted out.
The most representative samples have been photographed. Information of the samples and photos have been added to the drill core database.
An example of a drill core sample (drill core no F353; from the depth of 286,1 m; amphibole-biotite gneiss)
