Anybody experienced cast iron degradation?

[Mart]

I'm looking at the bores on the crusty flatty. It's a 39/40 99 model.

Certain parts of the bores on 3 of the cylinders have (I can't think of a better expression) "degraded". The surface has a consistency like, carbon, is the best way I can describe it. I scrape through this soft layer and there is good metal behind it but it is very uneven. It's not like scraping some rust off where you can sometimes have a surprisingly good surface beneath.

Anybody else found this?

Mart.