For what its worth, the USGS website keeps going down and coming back up:
https://astrogeology.usgs.gov/search/map/Moon/Geology/Unified_Geologic_Map_of_the_Moon_GIS
So, if it doesn't come up for you, try again later. It was working fine when I wrote this content, but did go down once while I was writing it. Then it came back, but is down again as I write this comment.
