When speeded up, these solid rivers of ice seem to flow, just like liquid rivers. 

 

This is the titanic force that cuts down mountains and levels the surface of continents. 

 

The ice is now entering the last stage of its descent. As it gains speed, huge crevasses open that extend out to its very core. It’s reached the ocean and millions of tons of ice have lost the support of their rocky bed. Something must give. These ice falls are an ominous sign of what is about to happen, a rupture deep within the glacier.