As you walk east along the shore at Seatown in Dorset, you reach Ridge Cliff from which numerous boulders have fallen over the years, and accumulated across the beach and into the water. What is most interesting is the great variety of shapes, colours, textures, and compositions. They represent all the different strata that make up the 80 metre high cliffs.
Nice rock portraits, Jessica. Do you know how that crust of iron-colored rock forms around the grey rock? It shows in your Seatown Beach Bolders 9, 11, and 12. I see that formation on much smaller stones I find along the Vermilion River in Ohio.
Hello Linda. No, I do not know what creates the rusty deposits making patterns on the blue/grey rocks. They are very characteristic of boulders in this area. It is clear that it is a separate layer on the rock and was formed in situ during the laying down of the strata. In contrast to this, in other places along this stretch of coast, blue grey rock boulders of a different origin weather on exposure to the rusty colour by oxidation of the iron minerals in the rock. Here there is a distinct rusty layer formed before exposure. Iron nodules are common in the rocks at Seatown and also at nearby Eype; and isolated nodules frequently lie on the beach. I know that some of those at least are iron pyrites or Fool’s Gold – and fossil ammonites made of this also occur on the shore.
What a beautiful ironized (?!) ammonite. Thank you for posting its photograph. If you aren’t sure how iron oxide came to coat those boulders, I’ll continue to suspect that it’s the work of my old friends, the iron bacteria.
Your theory could be correct since the iron nodules and layers occur between the layers of limestone, shale or marl. I’ll do a little further investigation to see what I can discover.
Wonderful colours and shapes Jessica – some of them definitely seem similar to parts of Inishowen in Donegal.
One day I am going to get to Inishowen and find out for myself!
Let me know if you make it over Jessica – its not too far from me, and you can have a local guide!
Thank you, Adrian. I’ll be sure to let you know.