How does thermal contraction shape the topography of an ocean basin?

Thermal contraction is a primary factor in shaping the topography of an ocean basin as it moves away from a spreading centre.

At oceanic ridges, the lithosphere is warm and thermally expanded, which causes the ridge crests to stand elevated about 2 km (1.2 miles) above the surrounding seafloor. As the oceanic crust and upper mantle are carried away from the ridge, they lose heat and undergo thermal contraction.123

This cooling process causes the seafloor to subside, with the depth of the ocean basin being proportional to the square root of the crust's age. Most of this cooling and subsequent subsidence occurs within the first 70 to 80 million years, eventually resulting in a deeper, more stable ocean floor. Consequently, the width of an oceanic ridge is defined by the distance required for the plate to cool to a steady thermal state, which explains why faster-spreading ridges are generally broader than slower-spreading ones.3