After the fourth row I dug out the entrance so we could get in and out of the igloo. Here's a view from below of the Icebox form in place. The length of the pole is adjusted for each row to accomodate the curve of the walls. One end of the pole is attached to the block form, the other to a stake in the center of the igloo floor. The stake anchors the form so the new block will be in the right position; things went awry several times when the stake broke loose.

Photo by David Pendleton.