They May Affect Ice On The Surface
Scientists have concluded that the movement of magma underneath the earth’s crust causes the tectonic plates on the surface to move. They slide around on the ocean of magma, so slowly that the movements are imperceptible but measurable over the long term.
A very similar scenario exists between the subglacial lakes and surface ice sheets. As the water flows around and drains into the Southern Ocean, the ice moves around. This movement causes the lake water to flow even more rapidly; this relationship between the lakes and the glaciers can actually be seen by measuring surface ice.