“ Mistour ,” replied the guide.

“ Ja mistour ,” said one of the Icelanders in a tone of alarm.

“What does that word mean?” I asked uneasily.

“Look!” said my uncle.

I looked down upon the plain. An immense column of pulverized pumice, sand and dust was rising with a whirling circular motion like a waterspout; the wind was lashing it on to that side of Snæfells where we were holding on; this dense veil, hung across the sun, threw a deep shadow over the mountain. If that huge revolving pillar sloped down, it would involve us in its whirling eddies. This phenomenon, which is not infrequent when the wind blows from the glaciers, is called in Icelandic mistour .