Engine casings

Now most of the bearings are out of the engine casings, I can give the casings a jolly good clean and inspection.
Generally the casings appear to be in good condition, but I was a little worried to see signs of 'chattering' on the insides of the crank casing.

I wonder what might have caused this?
Will new bearings solve this? and has the engine been damaged now because of this wear?
Do I have to get them machined smooth again?

Plenty of things for me to be thinking on over the next couple of weeks while I am away from the garage.