Viewed from the end, the sections in a good butcher block should be atached to each other along their long edge.
\nGood:\n\n----------------------------\n| | | | | | | | | |\n| | | | | | | | | |\n| | | | | | | | | |\n----------------------------\n\n\nBad:\n-------------------------------\n| | | | | | |\n-------------------------------\n
The top one above is very unlikely to warp. They should be assembled with alternating pieces having the curve of their grain in opposite directions.
[link|http://www.johnboos.com/boosblock/jbc0002.asp|Examples]:
First and second ones, dishwasher safe.
Thrid one, probably not.
Fifth one, indestructible.