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How is the Gauss-Matuyama geomagnetic reversal connected to the beginning of the Pleistocene?

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Map showing the extent of the Laurentide, Cordilleran, and Greenland ice sheets during the Wisconsin glaciation, roughly 100,000 to 11,000 years ago. The Laurentide Ice Sheet covers most of present-day Canada and parts of the northern United States in light blue, the Cordilleran Ice Sheet covers the Pacific Northwest in teal, and the Greenland Ice Sheet is marked in purple. Modern international and state or provincial boundaries are outlined for reference. — Pleistocene Epoch Ice sheets during the Wisconsin glacial episode penetrated deep into North America.

The Gauss-Matuyama geomagnetic reversal is a critical chronostratigraphic marker used to define the beginning of the Pleistocene Epoch.

The formal base of the Pleistocene is defined by the Gelasian Stage, which begins 2,588,000 years ago. This boundary is established at the global stratotype section and point (GSSP) located at Monte San Nicola in Sicily, Italy. The Gauss-Matuyama geomagnetic reversal—a significant shift in Earth's magnetic polarity—occurs in close proximity to this boundary. Specifically, the marker bed for the base of the Pleistocene is situated approximately one meter above the strata that record this paleomagnetic boundary. Because this reversal is a global event, it serves as a vital tool for geologists to correlate the onset of the Pleistocene across different regions of the world.123