GISP2-D Borehole Depth

REFERENCES:
 
50, 51

DATA DESCRIPTION:

The length of the 3-km borehole at the GISP2 site was measured by two
completely independent geophysical logging systems, the University of
Copenhagen system (UCPH) and the U.S. Geological Survey's temperature
system (USGS).  Both systems utilized steel logging cables.  The depth
calibration factor for the UCPH system was determined from the measured
length of the GRIP ice core while the USGS system was calibrated using a
fiberglass tape measure with a low coefficient of thermal expansion.  The
accuracy of the depth measurements for both systems is estimated to be 2-3
m at a depth of 3 km. 

Inclination/azimuth measurements from the UCPH logger have been used to
calculate the true vertical depth of the borehole from the measured total
slant length. 

DATA:

logger used	true vertical depth (m)	slant length (m) 

UCPH	3047.8	3056.5
USGS	3047.9	3056.6