At the wiki you might find some tips: http://ringofbrodgar.com/wiki/Finding_h ... ,_and_soil
Tips I remember now:
- to test if there is ball clay, in shallow waters you can dig from your boat.
- sometimes underground water streams are near and/or cross each other, so you might get a well that gives you Q10, and this water comes from a regular Q10 stream, but in another well near you might get better Q than the one you already have and it would belong to your higher Q stream. I have found Q10 in the middle of an area where there was 3 wells Q 22, 28 and 31.
And there is this interesting theory, that ofc needs to be confirmed:
#tip No.21343456
When searching for quality nodes of anything, turn on grid display on Ender's minimap. Center of quality always appears at crossing of those red grid lines. (Sadly i have no screenshots atm to picture it better)
It belongs to this post: viewtopic.php?f=2&t=22742&hilit=soil&start=330#p379154
I have found some nodes using this idea, but ofc there is not a node on every crossing of grid lines.