Gravel

consists of smaller and larger rock fragments that have become rounded during long distance river transport. The Main deposited vast amounts of gravel during the Pleistocene (2.6 million to 12000 years ago). The river terraces are the result of the climate change between cold and warm periods. Huge amounts of rock debris was formed during the cold periods. The rock fragments were transported by the river Main and deposited as gravel on the floodplains.

When the climate warmed, the Main swelled with additional water and carved a new channel into the floodplain deposits. At the same time, the Taunus was uplifted thus intensifying the erosive power of the river.

The sediment is very porous. These pores contain water and air. The water in the gravel beds contained iron, which oxidised when it was exposed to the air. This gave the sands and gravels their rusty red colour.

The Main terrace landscape

is characterised by a series alternating slopes and level areas, looking like stairs. This panel stands on a young terrace. The Main gravel deposits are covered by fertile residual loess which has been washed down the slopes. The steep path takes you to the “Steinernen Strasse“. This gradient was created by the Main as it carved its channel deep into the rock. Near the Fähncheskreuz you can see an older terrace where the ground levels out again. While the surrounding landscape was uplifted, the Main cut deeper and deeper into the subsurface rocks. This is how our river terrace landscape was formed. The “buried ocean” is exposed once more along the slope.