Mr. Van Herck is a newcomer to the region, a rare outsider in the business. He was an Internet entrepreneur, a wine geek who wanted to get into the business. His dedication to biodynamic viticulture led him to Guy Bossard, the longtime proprietor of l’Écu, who was a pioneer in biodynamic viticulture, having made the transition some 20 years ago. Mr. Bossard was looking to retire but had no heirs. They were like-minded enough that Mr. Bossard sold to Mr. Van Herck and has stayed on as a consultant.

Image A bottle from Domaine de la Pépière. Credit... Damien Lafargue for The New York Times

“We don’t make the best wines in the world, but we make them with conviction,” he said.

L’Écu’s three main Muscadet cuvées are meant to show off the qualities of the three major terroirs they farm. Of the wines from 2013, a difficult but excellent vintage, Gneiss is the softest and most easygoing. Orthogneiss is both subtler and more concentrated, while Granite is densely mineral, lively and with great finesse.

“We have to stop thinking of Muscadet as something you have to drink three months after you buy it,” Mr. Van Herck said. “These three expressions are for 10 to 15 years in the cellar.”

Among the best Muscadet producers, generational transition has been something of an issue. Marc Ollivier of Domaine de la Pépière, who makes wonderfully expressive Muscadets from a range of terroirs, has in the last decade taken on two young partners, Rémi Branger in 2006, and Gwénaëlle Croix in 2013. André-Michel Brégeon, who makes substantial, energetic Muscadets from the gabbro rock here in Gorges, has taken on a protégé, Frédéric Lailler, as he nears retirement.

Pierre Luneau and Monique Papin of Luneau-Papin, luckily, have a son and daughter-in-law, Pierre-Marie and Marie Luneau, who have taken the reins of their excellent estate. Jo Landron, who has made wonderful wines at Domaine de la Louvetrie after taking over for his father in the 1980s, is not yet near retirement, but he has a son who has become a grape grower.

In Mr. Landron’s case, an earlier generational transition was not easy. After he took over, he stopped using chemical herbicides and began plowing the soil. He started farming organically and, eventually, biodynamically. His father, Pierre, did not approve. “But he was retired,” Mr. Landron said.