Rippelmarken am Gymnicher Porz - Altenahr, Rheinland-Pfalz, Germany - Places of Geologic Significance on Waymarking.com

North of the castle Are are the remains of the Gymnicher Porz. It was a lower gate complex on the way to the castle, which closed off the castle hill in connection with a wall. The plant was built into the rock of the mountain slope.
Directly on the path, a few metres before the archway, there is a vertical piece of rock approx. 3m high, which clearly shows ripple marks.
It concerns a piece of fossilized seabed.

Slate stones are from marine sediments from the Lower Devonian (~ before 410 million years) emerged. Slate stone is a pellitic sedimentary rock and consists mostly of clay minerals (eg, montmorillonite, illite and smectite). Other parts are quartz, feldspar, and carbonates. As a sedimentäry rock this rock slab was part of soft seabed 400 million years ago.

When seafloor comes close to the surface, the small grains of the sediment get into the effect of surface flow. With a function of flow velocity and grain sizes particles are torn from the ground and transported by the water. Where the flow drops (eg behind obstacles) the grains sink to the bottom again. This causes wavy patterns in the sand ground.

Experts distinguish two different types of ripple marks:

1) Current ripples are formed by flows coming from a constant direction. They form more or less parallel wave pattern with unsymmetrical peaks: the flow-facing side forms gently sloping hillside. The other side drops significantly steeper. The mean height of the peaks are found today about 3-5 cm. The distance from crest to-valley (the wavelength) is between 4 and 60 cm.
This slab shows current ripples.

2) Oszillation ripples arise when the causing flow oscillates, ie periodically changes direction. Are the two directions real opposite directions (tides, ebb and flood) the ripples form intricate wave pattern with symmetrical peaks.

Sometimes the sandy patterns petrify and the structures in the beach floor remain. This must have happened here a long time ago. When geological events formed the Ahrgebirge, this former piece of beach reached its vertical position.

Waymark is confirmed to be publicly accessible: yes Requires a high clearance vehicle to visit.: no Requires 4x4 vehicle to visit.: no Public Transport available: no Parking Coordinates: Not Listed Access fee (In local currency): Not Listed Website reference: Not listed

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