Comments on "May 5, 2015"
The western side of Nectaris is higher than most of the basin. There is a line from Theophilus to Beaumont. Using the line tool in LROC this appears to be a fault line, like the rest of Nectaris settled down leaving this western part higher. It really threw me for a loop when I first started to observe the Moon. It appeared to be an area that was walled off from the basin, and I had no idea how that could have happened.
Note there is a new anaglyph (red/blue 3D) of Theophilus' steep eastern wall on LROC news site. Don't forget to click on the image to get some more views.