Pointing towards a bluish mass of ice in a distant valley, he explains that in the 1930s the Black Rapids Glacier became the fastest moving ever recorded, sometimes advancing as much as 200 feet a day.
On day three, after about 60km of riding, we crossed the 3, 900m-high Tosor Pass, where a sheer cliff of ice and snow gave way to a narrow corridor with the shimmering Kerege-Tash Valley below.