Law of horizontality

The law of horizontality states that sedimentary layers are generally deposited horizontally or parallel to the Earth's surface.
It is also used as a basic principle in the study of geology and stratigraphy to interpret the depositional environment and history of a sedimentary rock unit.
This notion of history resonated to me.
With this principle in mind, I decided to add all the color strings horizontally on these 4 artworks.
I felt having parallels to the ground or horizon was completing each piece.
They are symbolically here to help to determine the relative ages of rock layers and to understand the sequence of events that occurred during their formation.