I have downloaded four geology tiles and merged them together. It works, and I can then go on to customise the tiles to colour code each geological unit no problem, but those four lines joining the tiles I merged look so messy and I want rid of them. I get these lines when I merge shapefiles to make the merged file, and when I merge layers to make the merged file. No solution as of yet.
I imagine it could be a stylistic thing, where I need to make the borders transparent or something. Thoughts?
You can try dissolving features based on one common attribute. This should solve your problem. This may create multi-part polygons that you can break by Multipart To Singlepart algorithm.
So for geology maps specifically, I was able to rectify this by simply removing the outlines of the rock units after I filled them in. For the type of map I'm making, it is fine to just make your own boundaries with polylines, or just simply leave them empty because there is only one 'type' of geological boundary between rock units on this map and I think it actually looks better with no outline as this is more realistic given scales (too many geological maps have boundaries that are too thick).
However, fixing this issue for other purposes could be important to others so I will leave the question up.
