Flat strips of tooth chiselling can be seen running down the length of the shaft. These marks those areas of the shaft that will be carved into flutes during the next stage of work, which for some reason was never undertaken here.
Between the strips of tooth chiselling are similar strips of finer flat chiselling. These equate to areas between the flutes. This series of flat surfaces running around the shaft means that at this stage of work the shaft is actually facetted rather than completely rounded. This is a standard way of preparing the surface of a column shaft for fluting and can also be seen on the columns of the Temple of Vespasian.