Ah yes, strip mining at y: 10, is it? Seems to me you were in a mineshaft and couldn't find an easy to get ore such as iron and starting using alternatives to look for it..

Such as the time you seem to magically know there was iron store away in the ground of a dead end

Or when you dug straight into the ground once again to run into iron and then move on as if you knew there would be nothing there...

or when you stumbled upon coal, and mined it, but instead of mining all the coal, you seemed to be interested in some stone as seen here?

only to find some more iron! how lucky..