Geology Reference
In-Depth Information
Figure 1.13
ABAB tie between bases in a magnetic survey with a 1-nT
instrument. The estimated difference between the two stations would be
89 nT. Note that the plotting scale should be appropriate to instrument
sensitivity and that it may be necessary to 'remove' some of the range of the
graph to allow points to be plotted with sufficient precision.
Differences should be calculated in the field so that any necessary extra links
can be added immediately.
1.6.3 Base networks
Most modern geophysical instruments are accurate and quite easy to read,
so that the error in any ABAB estimate of the difference in value between
two points should be small. Even so, the final value obtained at the end of an
