The German wine regions are some of the most northerly in the world. The climate is extremely marginal for growing grapes, and the extremely steep slopes that are characteristic of Germany’s most famous wine regions are extremely hostile towards agriculture. The most famous region is the Mosel-Saar-Ruwer valley. The finer vineyards here are situated on extremely steep slopes, giving lower yields but better solar exposure and ripeness. Most of the region has slate soil and this shows up in some of the wines as a mineral-like flavour. It is here that the finest Riesling is produced. Other regions of Germany are less well-known but still produce quality wine. The Pfalz is the highest-producing region and makes much of Germany's inexpensive bulk wine. The Rheinhessen is the physically largest region and produces mostly Muller-Thurgau for low end wines. The Rheingau is hilly terrain and produces high end Riesling, but in a less “exuberant” style than the Mosel.