I want to return to this shot for a moment. Notice the transom line with
the line level stretched across the pit. We ran the line from a nail on
the barn above the datum point. The nail is 21 cm above the datum point.
The stretched line allows us to easily measure the depth of the pit at
any time--- Randy marked a rod with depths already calculated (by subtracting
the 21cm) and so depth is spotted in a second. The transom line is tied
to a post on the other side of the hole, also marked with datum point elevation.
The unit is at the bottom of Level 3 in this photo. |
