Depends largely upon where we moved them all to.
Let's say we moved them all to the UK, and piled them up in the vicinity of Scafell Pike, which is currently classed as the highest peak in England.
Scafell Pike would now be bigger than Mount Everest, and there will be an even bigger influx of migrants into the UK than we currently have to endure.
Many of these immigrants would of course be newly destitute Sherpas who would be compelled to travel from Nepal in order to pursue their previously lucrative mountain guiding careers.
What with all the extra rocks, Sherpas and mountaineers making our tiny island top heavy it would start to sink into the surrounding ocean, causing the likes of Liverpool and London to disappear forever under the waves (together with all those beastly Scousers and Cockneys), and we would all be eternally grateful for those small mercies.
Hmm, when do you think you can start moving these rocks?
Well if you're thinking that it would tilt the planet or something, it wouldn't. I saw a thing that said if every person in the entire world jumped at the same time, nothing would happen.
Lets just say, it would not be good.
Nothing except a big pile of rocks