North of Ampuis, on the Côte Brune, the parent rock is schist with proportions of dark and light mica, giving the soil its namesake dark brown color. To the south, the slate contains gneiss and weathers with it to a lighter grey, to which the vineyards owe the name Côte Blonde.
The wines are correspondingly different: those from the north usually more powerful and robust, those from the south more delicate, charming and smooth - although there are of course also cuvees from both zones. The most charming wines, however, often owe their character to the admixture of Viogner, thus, white wine grapes, which is allowed here to a maximum of 20%. However, such a high percentage is rare, and especially in the Côte Brune, the wines usually consist entirely of Syrah. Other varieties are not allowed.