![These tally marks are at the very center point of Hoover Dam's inside 700 step staircase. The tour guide said their history has been lost over time. Any idea what they are? : These tally marks are at the very center point of Hoover Dam's inside 700 step staircase. The tour guide said their history has been lost over time. Any idea what they are? :](https://i.redd.it/these-tally-marks-are-at-the-very-center-point-of-hoover-v0-lmm3x1cu7h691.jpg?width=4032&format=pjpg&auto=webp&s=52db31d88038b4aafacfb00081aced36c19470fa)
These tally marks are at the very center point of Hoover Dam's inside 700 step staircase. The tour guide said their history has been lost over time. Any idea what they are? :
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