How did the direction of Sumerian cuneiform writing change over time?

In the earliest stages of Sumerian writing, the script was organized in columns that ran downward.1

As the writing system evolved throughout the 3rd millennium BCE, it became increasingly conventionalized and cursive. During this transition, the orientation of the signs was turned on their side, and the standard direction of writing was fixed to run horizontally from left to right. This shift in orientation occurred alongside the development of the characteristic wedge-shaped strokes, which were created by pressing a stylus into soft clay tablets.12