Bart Belteshassur:
Geology can determine how,why, and what happened and suggest approximent time frames (by that I mean within X million years) and archeology then places that information into a historical context using the evidence specific to the strata.
Indeed. There must have been other factors in determining the period. Because the timing and margins for error indicated don't exactly align with the traditional dating for the 'expected' kings, it's evident that they made a determination beyond only saying it 'must have been when we think Jeroboam reigned'. Yadin also refers to styles of pottery at different sites as well. The margins for error given seem consistent with carbon dating error rates for the approximate age, but it doesn't say.