Yeliu Concretions

Concretions are places where the mineralization over time has produced a shape that is different than the surrounding rock. Sometimes the start of a concretion is a dead soft body animal that diffuses into the surrounding rock and then as the minerals replace the organic material the result is different than the surrounding rock. Fossils are usual the shell or bones of the dead animal that have no chance of diffusing after death.

At Yeliu there are plenty of concretions in the sandstone. The mineralization produces a more resistant rock that weathers out from the sandstone.

It's fun to guess what the animal was that produced the concretion, maybe a jellyfish? Sometimes in the middle of the concretion is the trace of the dead animal.

The ocean levels have changed many times in the past millions of year, so the mineralization can be done over and over. And being on the seacoast, the concretion can be the start of a strange potholes

But concretions are not particular to Yeliu, this one is from Yeliu.

but this second one is from Orcas Island in Washington State on the other side of the Pacific Ocean.