The tablet represents myths associated with watery constellations. These include Aquarius, the “Water Bearer” and Capricornus, “The Water Bison”, among others. See:
http://www.space.com/spacewatch/051007_night_sky.html
Aquarius seems to match the central figure on this tablet (including the deep line to the right) and Capricorns is well represented by the four fish- skeletons or downward branching lines with the upturned corners, in my opinion. The pottery head found directly above the tablet could represent the head of Pegasus stylized as the square with invisible lines representing serpentine streams of life blood flowing from it.
See: http://lithiccastinglab.com/gallery-pages/clayheadkasslypage1.htm
http://lithiccastinglab.com/gallery-pages/kasslytabletbirdlarge.htm
The faint line superimposed over the central figure exactly corresponds to the moons path as it crosses the water bearer (Aquarius) and Capricornus.
Incidentally, the Archaeologists that aren’t sure why the tablet was made are wrong about the date too. They blatantly assume all engravings are from 1000 years ago. It more likely dates to at least 5000 years ago, based on the site materials that it was found with, including Greenbrier projectiles, hand-axes, hematite cones, and thousands of other archaic artifacts.
See? I was right. ;^)