The answer is it then remain preserved over the centuries. Since a layer of the volcanic ash preserve the art and architecture to the residents, the city of Pompeii then provide a snapshot of the Roman art.Hope this would be of help.
bolder darker and makes them more important
The Parting of Lot and Abraham is about their literal parting - Abraham took his family to Canaan, as God wanted him to, whereas Lot went to Sodom, and defied God's wishes. Now, having this in mind, maybe this mosaic does symbolize B. heaven, as Abraham and his family would go to heaven eventually, because they obeyed God's orders and wishes.
