riddle - separate with a riddle, as grain from chaff screen sift, sieve, strain - separate by passing through a sieve or other straining device to separate out coarser elements; sift the flour
Causes of the Civil War: Bleeding Kansas. Proposed by Sen. Stephen Douglas of Illinois, the Kansas-Nebraska Act essentially repealed the line imposed by the Missouri Compromise. Douglas, an ardent believer in grassroots democracy, felt that all the territories should be subject to popular sovereignty.
These two parts were the southern states known as Confederacy and Northern states known as Union. The main and the declared cause of the conflict was the issue of abolition of slavery. However there were many other underlying issues adding to the conflicts that resulted in the war.