I just joined the game and all the dirt is gone. It must stop.
Building skybases always leads to half of the dirt being despawned from the map and other half destroyed by players who want to upgrade and do other stuff.
Yes, it is the most comfortable zone to have a base in, I understand, but don't be d*cks, let other people play the game it was originally intended to - by digging dirt, upgrading and building on the surface. Stop removing dirt for your own convenience and feeling of safety. Think about the other players who don't want your skybase to destroy the map, think about greater good.
Instead of building in the sky, go deep under the ground, protect the dirt around it to not let anyone come too close to you. Don't let anyone destroy the dirt above, under and on sides of your base. If some dirt is destroyed place dirt blocks with tool as a replacement. Protect the base by building extra stuff on the surface (like gates, spikes). Place turrets and traps if needed. Use cubes to create neutral zones, use octopuses as a weapon. Think creative. It would be just as safe as having a skybase, but it won't create troubles for everyone else on the map.
You can read about safe digging and fighting invisible players in this topic: viewtopic.php?f=192&t=25475
Remember: raiders are also people. You can talk to them and understand what do they want to make peace. It would be a better strategy if you want all raids to stop. I myself talked to at least 3 raiders and all of them had good reasons to hate you and your skybases. Just talk. I'm not saying it will 100% work but you can try because you have nothing to lose.
Also @Commander & @Eric Gurt, if you cannot do your job by resetting the map when all dirt is gone and game became unplayable, then give administartor powers to someone else. To someone who will do the job you aren't doing. Game should always have dirt for new players who just joined. Imagine a Minecraft server where new player spawns in the world but there is nothing but bedrock all around - that's what you do, but in SD2D.