I was reading about states of planetary ice in the following article. http://www.sciencedaily.com/releases/2015/06/150622182455.htm when it struck me that perhaps we should not assume that pressure increases as we descend into a large object. Like a cathedral ceiling a large cave does not exert pressure on the cavity within. This is because of the lateral forces supporting the structure. Do we assume this does not happen inside large rocky objects? Clearly in a large liquid object this would occur but in a cool or frozen object could not the lateral forces negate the vertical forces meaning a ice planet does not experience the extremes of pressure discussed in the article?