Does it happen automatically on map load?

The mod creates a button in the upper left corner which when pressed processes the entire map.

The mod creates a button in the upper left corner which when pressed processes the entire map.

Why do this? What is the meaning and utility of this mod?

It's "un-exploring" of the map. Your save game file will be much smaller.

Hi, does this mean i can safely delete explored areas of the map (away from my base), and then i can re-explore (and find newly randomised ores, or new ores that a new mod added to the game, but they didnt show up yet?) :)

for example, i added madclowns mod to my existing game, which adds another 9 types or ore patches: https://mods.factorio.com/mod/Clowns-Extended-Minerals but a lot of my map was already explored, and now i will have to explore a lot lot more just to have a chance of seeing the new ores, which can be seen on thee 1st post here) https://forums.factorio.com/viewtopic.php?f=185&t=58136
it would be cool to be able to see them on the map, and to save some drive space too :)

Yes, a chunk that is deleted will regenerate with updated settings/mods.

cool, thanks strath :)