Chunks load in glitchy patchwork patterns, often loading distant chunks before ones closer to the player, this problem persisted throughout 1.9 also, and can only be fixed by installing the Optifine mod. Chunks will often load and then reload as the player viewpoint is moved. Note that often the top halves of trees and mountains fail to load too. This is most often seen when moving at fast speed such as horseback, boats and flight.