Acacia tree logs fall through ground
chopped an acacia tree and had the logs fall through the ground at -1332W -162N on Terra
often when the logs appear to fall through the ground, I've found now that it may be more visual than actual. If you zoom in and slowly run your cursor around the stump, you'll often find your cursor becomes the hand and you can pick up the logs.
The falling through the floor issue with logs has been a recurring bug since Alpha, and I think its really that the "grass" windowdressing graphics are merely overlapping the logs.