In its meaning of "wooden roof tile or cladding tile", not "gravel".

"Ancelle" is a word used primarily in the Alps, apparently, for what elsewhere is known as "tavaillon".

shingle ... (2) A thin rectangular piece of timber about 400 x 130 x 6 mm, used like a tile for covering roofs or walls. ... Shingles were used in ancient Rome and split shingles (or shakes) were common in medieval Britain. In the USA shingle roof fires are fought from inside the house.
[Soctt/Penguin Dict. of Bldg]

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Note added at 30 mins (2009-05-12 12:35:45 GMT)
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Most of the NORWEGIAN STAVE CHURCHES were small, simple buildings with a short nave and a narrow chancel. The roofing was usually wooden SHINGLES, and both the roof and the walls were tarred
www.allscandinavia.com/stavechurches.htm

Another typical and well-preserved example of the STAVE CHURCH is the Borgund church (c. 1150) in Sogn og Fjordane county, NORWAY. Its complicated, ambulatory plan utilizes freestanding posts in the nave to support the tall central portion of the structure. The church’s six levels of gable roofs, shell-like exterior SHINGLES, and elaborate carvings of grotesque masks and other motifs give it a picturesque and vigorous appearance.
http://www.britannica.com/EBchecked/topic/564364/stave-churc...

The highlight for me was the STAVE CHURCH from Gol (224 kilometers northwest of Oslo) built c. 1200 and transported here more than 100 years ago. In the 10th through the 13th centuries, more than 800 STAVKIRKER were built using the materials at hand -- wood (no nails) covered in wood tar, resulting in their dark color. Now only about 30 remain. The Stavkirker were gabled fantasys with no windows and therefore little interior decoration. Their design incorporated the Viking symbol of might: dragons, combined with Christian imagery. The wooden roof SHINGLES resemble fish scales
http://www.virtualtourist.com/travel/Europe/Norway/Oslo_Regi...