The Gap locality near the center of the Alpena Amberly Ridge contains several stone hunting blinds along an esker that serves to constrict the flow of migrating caribou to a relatively narrow valley. The esker exhibits a gap at one point along its run. This is not only where the site gets its name, but also provides an outlet for caribou to find more space on the other side of the esker.
Hunting blinds were constructed at the opening of the gap to take advantage of the animals exploiting it. The behavior of altering one’s environment to facilitate resource extraction creates an ecological niche for humans that did not previously exist. This is an AUV image of the esker at the Gap site.
One of the hunting structures at the Gap site is a V shaped blind, as seen on the left. In and around this construction were stone tools associated with a microlithic industry, including micro-blades, burins, and utilized flakes.