The Oderteich is a lake in Lower Saxony, Germany. The lake served as water reservoir for downstream mining activities (Sankt Andreasberg), nowadays being used also for recreational purposes. We had a stop at the lake during our trip to Harz and could observe the lake surroundings from close distance. The water has a reddish color given by dissolved humid acids from dead plant materials.
We noticed some big blocks of granite around the lake and were interested to know more about them. It seems that the lake has been completely surrounded by granite but with time, this has been eroded by transformed in sands and gravel. However, some boulders are still present as a prove of geological transformation in the area and look like swimming in the sandy material towards the water. Walking around the lake I was able to get a small sample for my Sand Atlas (sample no. 2296):
Germany – Lower Saxony – Oderteich