Schwäbische Alb

From the Swabian Jura entry in Wikipedia:

The Swabian Jura (in German Schwäbische Alb), sometimes also named Swabian Alps in English, is a low mountain range in Baden-Württemberg, Germany, extending 220 km (137 miles) from southwest to northeast and 40 - 70 km (25 - 43 miles) in width. It is named after the region of Swabia.

The Swabian Jura occupies the region bounded by the Danube in the southeast and the upper Neckar in the northwest. In the southwest it rises to the higher mountains of the Black Forest. The highest mountain of the region is the Lemberg (1,015 m (3,330 ft)). The area's profile resembles a high plateau, which slowly falls away to the southeast. The northwestern edge is a steep escarpment (called the Albtrauf or Albanstieg, rising up 400 m (1,310 ft), covered with forests), while the top is flat or gently rolling.

All pictures are © Dr. Günther Eichhorn, unless otherwise noted.

Blautopf

From the Blautopf entry in Wikipedia:

The Blautopf (Blue Pot) is an upwelling spring with a distinct blue color. It is the source of the river Blau. It is located in the city of Blaubeuren, approximately 16 km (10 miles) west of Ulm. It forms the drain for the Blau cave system, where the Blau after 14.5 km (9.0 miles) flows into the river Danube in the city of Ulm. Because of its high water pressure, the spring has developed a funnel-like shape, which at its deepest point has a depth of 21 m (69 ft). The water's peculiarly blue color, varying in intensity due to weather and flow, is the result of physical properties of the nanoscale limestone densely distributed in the water. The particles are so small that the so-called Rayleigh scattering of light takes place, preferentially scattering the blue color in the visible light. Similar effect is observed at the Blue Lagoon in Reykjavik, Iceland, and the Rio Celeste (Blue River) in Costa Rica, where the blue color originates from nanoscale silica particles.