Definition of "serac"

The smoke found its way out of the holes in the roof as it liked best; and nearly over the fire was a black smoky shelf, supporting several masses of that inferior white cheese, called Serac.

1826, The Museum of Foreign Literature and Science, volume IX, [Philadelphia, Pa.]: Published by E[liakim] Littell & T. Holden; New York, N.Y.: G. & C. & H. Carvill; Boston, Mass.: Kane & Co., column 2

Here and elsewhere the sérac, which is something between curd and cheese, may be advantageously taken instead of butter, which is almost always bad.

1891, The Alpine Journal: A Record of Mountain Adventure and Scientific Observation. By Members of the Alpine Club, volume XV, London: Longman, Green, Longman, Roberts, & Green, page 214

Note the Alpine cheese dairy on the Iseltenalp, where fresh dairy produce are made every day (milk, butter, cheese and serac).

2001, Switzerland (Michelin Green Guides), Watford, Hertfordshire: Michelin Travel Publications, page 184

Perhaps the finest part of it [the Lysjoch] is the grand sérac scenery of the Zwillinge Glacier. In August, 1876, a party of four, having missed the right track in crossing this pass when the snow was in very bad condition, were carried down in an avalanche of loose snow probably started by their own weight.

1838, A Hand-book for Travellers in Switzerland and the Alps of Savoy and Piedmont: Including the Protestant Valleys of the Waldenses (Murray’s Handbooks for Travellers), London: John Murray; Leipzig: Black and Armstrong; Paris: Galignani, page 368, column 2

Numerous blocks of ice, to which the name "serac" is given, covered the plain. These are large fragments of frozen snow, almost rectangular. They take their name from the resemblance they bear to a compact cheese called "serac," which is made from skimmed milk, and pressed into rectangular cans.

1854, Charles Williams, chapter VI, in The Alps, Switzerland, and the North of Italy: With Numerous Engravings, New York, N.Y.: Printed by Alexander Montgomery, 17, Spruce-Street, page 82

As you mount the Aletschhorn from the sleeping place, towards the lowest col from which you first overlook the Lotsch Glacier there descends, from a higher plateau, and on your right hand, a large mass of sérac.

1863 March, W. Wigram, “[Notes and Queries.] Intersection of the Lines of Bedding of the Névé by Blue Veins of Pure Ice”, in H. B. George, editor, The Alpine Journal: A Record of Mountain Adventure and Scientific Observation. By Members of the Alpine Club, volume I, number I, London: Longman, Green, Longman, Roberts, & Green, published 1864, page 46

The Boltoro Glacier […] The surface of the glacier is rough and uneven, broken by crevasses and covered by seracs and rock debris.

2017 October, Jamie Ambrose, Robert Dinwiddie, John Farndon, Tim Harris, David Summers, “Glaciers and Ice-sheets”, in Peter Frances, editor, Natural Wonders of the World, London: Dorling Kindersley, page 233