Ancient Tectonic Shift Caused a Massive Sea Level Drop

a) Global ocean crust production rate, with 95% confidence bounds, from Dalton et al. (2022), for the most recent 19 Myr of Earth history.

(b) Red field (left axis) is modern-day area-age distribution α(τ,0), determined using the age grid from Müller et al. (2016), and gray curve (right axis) shows how the modern-day subduction rate is partitioned according to the age of the downgoing plate at the trench.

(c) Age dependence of seafloor depth (black) and surface heat flow (magenta) for the plate cooling model (PCM; solid) and half-space cooling model (HSCM; dashed) from Stein and Stein (1992).

New research reveals that between 15 and 6 million years ago, a slowdown in seafloor spreading deepened Earth's ocean basins, causing sea levels to drop by 26–32 meters.

Published in Geochemistry, Geophysics, Geosystems, the study shows that reduced crust production led to less heat flow from Earth's mantle, contributing to global cooling and ice sheet expansion.

Evidence from coastal rock layers in New Jersey and Nova Scotia supports these findings, offering fresh insights into how ancient tectonic processes reshaped Earth's oceans and climate.