Quarts de Chaume, extraordinary small enclave within the Coteaux du layon appellation producing, only in the best vintages and usually only as a result of noble rot infection, sweet white wines from botrytized Chenin Blanc grapes or, increasingly, such grapes dried on the vine. Total annual production can often be as little as a few thousand cases, from just over 30 ha/74 acres of vineyard, supposedly the finest quarter, or quart, of the Chaume part near Rochefort-sur-Loire of Coteaux du Layon (see france, history, for details). The vineyards here have the advantage of a southerly exposition within a sort of amphitheatre. The brown schist and carboniferous soils are distinctive and result in powerful wines, particularly since the average vine age is high. The minimum grape sugar level in the must is 298 g/l, which is only rarely achieved, so few new investments are being made in this minuscule but potentially glorious appellation. The naturally high acidity of the Chenin Blanc grape endows these wines, similar to but rarer than those of nearby bonnezeaux, with impressive longevity. Domaine des Baumard has tried to secure permission for its continued use of cryoextraction but in 2014 it was decreed that this freezing technique will be outlawed from 2019, and that Quarts de Chaume is officially the Loire’s first grand cru.