(..) but they're dwarfed by those in the great ranges that divide the Indian subcontinent from Tibet. This is the boulder strewn snout of the giant Baltoro glacier in the Karakoram mountains of Pakistan. It's the biggest mountain glacier on Earth - miles long and over miles wide. (..)

(..) They're the most powerful erosive force on our planet. A moulin - a shaft in the ice opened by melt water as it plunges into the depths of the glacier. Like the water running through it, the ice itself is constantly moving, flowing down the valley with unstoppable force. (..)