There are a variety of contributing factors that can initiate thermal subsidence or affect the process as it is ongoing.
[1] As endogenous and exogenous processes cause denudation of the earth's surface, lower, warmer sections of the lithosphere are exposed to relative differences in weight and density.
[3] When conduction causes a section of the lithosphere to contract and increase in density, it does not directly add mass to the rock.
However, volcanic islands and seamounts with barrier reefs are shielded from wave and stream erosion, and thus the countervailing isostatic uplift is eliminated, causing them to subside and create an atoll.
The conduction of heat out of a section of lithosphere causes the rock to thicken and become more insulated to heat flowing in from the mantle; as this thicker section is buried by the descending column of the lithosphere, it descends into surrounding rock layers with a higher relative geothermal gradient.
The gigantic Wilmington Oil Field in the Los Angeles basin was formed as a result of this process.