When Snow Turned Red

In Carniola, red snow lay over white snow; the layers stayed distinct as they melted, and the red left rose-coloured earth.

Gibb proposed volcanic ash, or puzzolana resembling brick dust, as a possible coloring for several reported cases, not all colored snow.

At Siena, weakly red rain was reported on 28 and 31 December 1860 and 1 January 1861; De Luca found organic coloring, probably from an alga.

Separately, crimson snow from Captain Ross’s Baffin’s Bay voyage was linked to plant growth; Bauer reported a fungus-like *Uredo nivalis*.