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How did Late Ordovician glaciation change sea level at the start of the Silurian Period?

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Silurian paleogeography — Silurian Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the middle part of the Silurian Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

The Late Ordovician glaciation caused a dramatic global drop in sea level, estimated at approximately 70 metres (about 230 feet), which drained vast areas of marine habitat and exposed continental platforms to erosion. This glacial event significantly disrupted climates and habitats by reducing the available space for organisms in epicontinental seas.12

At the start of the Silurian Period, this trend reversed as the glaciers began to melt. Basal Silurian strata record a rapid rise in sea level, which reflooded these extensive continental platforms. This warming and glacial retreat, which occurred during the Rhuddanian Age, constituted a major phase of the Ordovician-Silurian extinction event. The subsequent maximum rise in sea level, associated with the melting of the Late Ordovician glaciers, corresponds to the first of several global highstands identified during the Llandovery Epoch.123