When it comes to Riesling, Germany’s regions and rivers are inseparable. The mighty Rhine lends its name to and frames the regions of Pfalz (Rheinpfalz in old money), Rheingau and Rheinhessen, while all the other rivers, including the Mosel and the Nahe run into it (the Saar and Ruwer are tributaries to the Mosel). And it is these rivers that created the steep, often stony slopes on which Riesling thrives yet where pretty much every other grape variety would struggle.

Crucially, all these regions are on the 49th and 50th parallel, formerly considered the northern confine of viticulture, where grapes struggled to ripen. This is exactly why site selection in steep, stony slopes has always been key to the quality of German Riesling: here, the late-ripening, hardy Riesling thrives and can soak up every last ray of sun. Today, Riesling ripens fully every year but the sometimes marginal climate, the dramatic topography and the various rock formations still bring incredible energy to the wines – whether grown on slate, schist, limestone, sandstone or shale.

If any river meanders, it is the Mosel, with its loops cut deep into the Rhenish Massif, creating precipitous slopes along a narrow valley. The blue Devonian slate gives the wines a uniquely salty tang and aroma in this still cool climate that always yields exhilarating freshness. Driving along the river is like scanning a wine list: such vineyards as Berncasteler Doctor, Piesporter Goldtröpfchen, Wehlener Sonnenuhr, Graacher Domprobst, Brauneberger Juffer, Ürziger Würzgarten and Erdener Prälat are legendary – the latter two on volcanic rock that lends a herbal savouriness to the wines. The wines from the tributaries of the Mosel, the Saar and Ruwer are equally ancient and famous. Just think of the Scharzhofberg or the Grünhäuser Abtsberg.

While Mosel, Saar and Ruwer make brilliant dry Rieslings, especially Grosse Gewächse,always defined by slate and fine acidity, off-dry and sweet styles find their apotheosis here too – no region makes Kabinetts as light-footed as Mosel, Saar and Ruwer, and every step up the Prädikat ladder will thrill. Estates like Joh.Jos. Prüm, Dr Loosen, Schloss Lieser, Fritz Haag, Willi Schaefer, Egon Müller and Maximin Grünhaus exemplify these styles.

Rheingau and Riesling are synonymous. The Rheingau is formed by a westward bend of the river Rhine as it flows north to pass the Taunus mountains. This created one long, south-facing, compact region protected from cool, northerly winds by the mountains and warmed by the river, which is at its broadest here. This is where Riesling’s quality was first recognised, where it was first planted as a single variety rather than part of a field blend,and where aristocratic estates first started selecting Riesling berries at different ripeness levels (thereby discovering Auslese). These were the producers who made Riesling famous and turned it into the most expensive white wine of the 19th century.

Despite being compact, the Rheingau offers varied soils – from quartzite and schist in the west to loess and loam in the east, with steep elevated sites like the Rüdesheimer Berg Schlossberg on the Rhine and the Kiedricher Gräfenberg further back and the famous, gently sloping, historic Brunnenlagen of Marcobrunn, Wisselbrunnen and Nussbrunnen. The region is warmer than Mosel, Saar and Ruwer and as a result the dry wines of the Rheingau, depending on site, altitude, soil and distance from the river, can be statuesque and soaring, or richer and more playful. Rheingau’s sweet wines are legendary – cooler years bring stiletto-like cut to Kabinetts and elegant Spätlesen, while the Auslesen, BAs and TBAs will outlast the people who harvest and make them. Estates like Robert Weil and Schloss Johannisberg play the full Riesling spectrum of styles with virtuosity.

The Pfalz is quite some distance from the Rhine. Its vineyards run along the east and south-east-facing foothills of the forest-topped Haardt Mountains as they slope down towards the flat Rhine Plain. This landscape was shaped by the Upper Rhine Rift, which pushed various rock formations such as sandstone and limestone to the surface, while volcanic activity adds some basalt. Pfalz enjoys a milder climate than Mosel or Rheingau, and has a long history of making dry Rieslings with more body and substance. The most famous part of the Pfalz is the so-called Mittelhaardt, where the Haardt Mountains provide a solid shelter from cool westerly winds: this is where you will find the famous Forster Kirchenstück, Pechstein and Jesuitengarten vineyards as well as the Ruppersberger Reiterpfad or the Königsbacher Idig. Some of the most brilliant Pfalz wines are made by the Bürklin-Wolf estate. Further north you will find the famous Kallstadter Saumagen, exemplified by Koehler-Ruprecht while further south, estates like Ökonomierat Rebholz and Dr Wehrheim make splendid dry Rieslings from the Siebeldinger Sonnenschein and the Birkweiler Kastanienbusch.

The Nahe, another river that runs into the Rhine, joining it at Bingen, gives its name to a long valley that gets gradually cooler and more marginal the further upstream and west you go. In the past, these Rieslings were sold simply as Rhine wines, but the region has put itself on the map with the advent of bone-dry Rieslings over the past three decades. Nahe vineyards are famous for dramatically steep slopes of varied rock formations. Shale and slate, volcanic porphyry and melaphyr, as well as sandstone, offer some of the most hair-raising dry Rieslings made in all Germany. While this cool-climate region can make wonderful off-dry and sweet wines, its real strength are its uncompromisingly dry Rieslings that can seem like essences of pure rock. They will appeal to the advanced Rieslings lover who looks for real excitement. Estates like Dönnhoff, Schäfer-Fröhlich and Emrich Schönleber have all honed exacting styles from sites like the Schlossböckelheimer Kupfergrube, Monzinger Halenberg, Niederhäuser Hermannshöhle and Bockenauer Felsenberg.

Rheinhessen is one of Germany’s most varied Riesling regions, largely on account of its size. Historically, its most famous part is the Roter Hang, or Red Slope, between Nierstein and Nackenheim, an escarpment of iron-rich (hence reddish) Permian rock facing the river Rhine. The dry Rieslings from the warm, steep sites of Pettenthal and Hipping are uniquely savoury and totally mouth-watering, with notions of crushed wild herb. Estates like Gunderloch, Keller and Kühling-Gillot are some of its best exponents.

Travelling further south to the Wonnegau, inland from the town of Worms and thus cooler, tertiary limestones take over, producing a lemony, bright, precise style of dry Riesling that seems to radiate with the coolness of limestone. Estates like Wittmann and Keller take this precision to the nth degree in sites like Morstein and Kirchspiel. This area also brings forth Germany’s most expensive and coveted dry Riesling, Keller’s G Max, which is made from old vines in a secret spot in these limestone vineyards. Latterly, the even cooler Zellertal, also on Tertiary limestone, has shown its mettle with a svelte, sleek style made by Battenfeld-Spanier in sites like the Schwarzer Herrgott. In Rheinhessen’s northwest, Permian and volcanic conglomerates already produce dry Rieslings with Nahe-like thrill – witness Wagner-Stempel from the Heerkretz site.

While the same rock formations can show similar flavour profiles across regions, it is the climate that really governs the final weight and acidity of German Riesling. The beauty of German Riesling lies in variety, offering something for every taste: from spine-tingling, bone-dry essences of rock to teeth-shatteringly sweet elixirs; from delicate, almost frivolously light-footed wines with haunting scents to solid substance with depth of fruit and texture. While regions can be characterised generally, various factors make a difference: the depth of the topsoil; its water retention or drainage; the gradient of the slope; the relative altitude; the exposure to morning, midday or afternoon sun, or to prevailing winds; the proximity to a river or forest; the age and genetics of the vines… Row orientation, planting density and training style – on single stakes or in wire trellises – can also favour a certain style, while harvest point is crucial. What happens in the cellar also has an influence: are grapes crushed and soaked before pressing or are they pressed immediately? Are they fermented spontaneously or with cultured yeast? In stainless steel or barrel? What size of barrel? The permutations of this matrix are endless – which in turn makes Riesling an exciting hunting ground for curious drinkers who enjoy nuance and finesse.