Development
Tells do not “pop up” over night but develop over time through repeated occupation of one place. Think of a tell as if it was a layer cake. The first level of occupation is like one layer of cake. Then the next level is the like the icing, then a third level is another layer of cake, then more icing, and so on. These layers build upon one another eventually making the site into a small hill (or a really tall cake!!).
Each layer of a tell does not necessarily represent human occupation.
Often, inhabitants abandoned a site and then resettled it again many years later. During the time of desertion, wind-blown soil and/or soil created by the natural decay of plant builds upon the site and become a stratum in itself. A site may go through several phases of occupation/desertion during its existence, with each phase becoming its own stratum. The archaeologist has to distinguish each of these layers in order to determine the history of the tell.