The logic and psychology behind #consolidation is pretty straightforward. Whenever there is a big move in one direction (the #trend), the appetite for buying or selling dries up as participants take the positions that they wanted. At this point (when buying/selling dries up), the #market has already repriced in the direction of the trend, and now is when the skeptics move in. It is the role of the skeptics and #contrarians to say that the market is mispriced. If they are right, the market makes a reversal. If they are wrong (or not very confident), then the market just consolidates a bit before the trend resumes.
This consolidation often takes similar forms: a small triangle (#pennant) or a slanted rectangle (#flag). But the meaning of the price action is similar, the markets is converging on an agreed upon price.