Book Source: "Riesling" the full diversity of the world's noblest vine from Christina Rischer and Ingo Swobada
Red Shale and Hayseed, Herbal aromas
High iron in the soil give the red color and a typical example is from the Roter Hang in Rheinhessen or the Ürziger Würzgarten in the Mosel. Spicy and aromatic, Riesling can get nuances of hayseed, spice and herbs.
Sandstone and Apricots
Several forms of sandstone is found all over the world where Riesling is grown. The southern Pfalz Mittelhaardt have classic vineyards with this. Forster Kirchenstück in Pfalz as well as many in Alsace (Kessler and Kitterlé). Stone fruits like apicots and peaches are common, but stand out on these weathered soils.
Shell Limestone and Mango
Limestone is usually identified by fossilized creatures and give a pronounced “minerality” to grapes, however as Riesling can be quite vigorous on these fertile, nutrient rich soil, exotic, ripe aromas can develop. The Wurzburger Stein in Franken is an example as well as Flonheimer Feurerberg (Rheinhessen) and Bruderthal Alsace.
Gneiss and Quince +Smoke
These primitive rocks allow riesling to accumulate tannins in their skins during longer ripening periods, then impart other aromas during fermentation. The aromas you may find in hot years can be associated with these soils, giving a slightly smoky aroma.
Loess-Loam and Grapefruit
The Kaiserstuhl in Baden has strong loamy soils that can store more moisture and induce growth. To counter it, winemakers may reduce yields. These cooler soils can promote citrus aromas, like grapefruit.
Porphyry and Minerality
The igneous stone is similar to granite and found in the Traiser Bastei (Nahe) as well as some Wachau and Kamptal areas. The aerated, water permeable and easily warmed stone can develop elegant riesling with high TDN, or petrol aromas, commonly associated with smokiness.
Keuper and Honeydew Melon
These heavy, clayey marl soils are not as common for Riesling but can be found in areas like Altenberg de Bergheim (Alsace) and Iphofen in Franken. The generally cool soil is hard to warm and tend to bring forth ripe, melon notes on Riesling. High sunshine in the area too is factor.
Blue Slate and green apple
Soils of the northern Mosel, Mittelrhein and lower Rheingau all have this character. The distinct fruitiness and delicate acidity in Riesling explodes on the nose. “Green apple sorbet” is one of my identifiers for Riesling on this soil.