Yes, you read that right, depth. There are lots of ways to describe the various moments of a plot as it develops, but I think in images, and when I think of plot, I see it in spatial terms regarding the depths of life it plumbs at different moments along the way.
To me, there are shallow days and deep days. Shallow days are those that tick on along in ordinary moments, almost on autopilot, never delving below the surface of the daily events. Deeper days are those where all the roiling scary elements beneath the surface of everyday life make themselves evident and inescapable. Using both kinds of experience gives a story a balanced pace that provides both necessary pauses and essential tension-filled direction.
Shallow days are those where the effort is put into getting through, doing what needs to be done, keeping on course–for example, getting the four-year-old to do what she doesn’t want to do, trying to get work done at the job, trying to eke out some small window of time for relaxation or reading. Shallow days move quickly, inevitably, and almost unconsciously forward. They draw the reader on by setting expectations, but often hint that something is about to change.
Change happens on the deeper days, when all the ordinary comes to a screeching halt and a deeper consideration of life is inescapable–for example, being at odds with someone close, experiencing a sudden traumatic event or marvelous moment. These are the experiences where everyday life has to be reconsidered and eventually reconfigured. That change does not come without resistance, and it often comes with extensive emotional drain. Deep days feel overwhelming, they encourage different paths of thought, and eventually, they usually even out into another version of shallow–a new routine to be followed, a new direction to be pursued.
Both kinds of day are essential to plotting a novel—shallow moments drive the story on through a regular sequence of events that propel a protagonist forward, ever forward. Deep moments put up a big roadblock and require the protagonist to reestablish the purpose and direction of that forward movement. The best novels, to me, are those that incorporate both kinds of moment, but use them to their own essential purpose.
The shallow moments create the trajectory, they help us understand who the protagonist is, the decisions which structured his or her existence and goals. Shallow moments show what normal life is, how it unfolds, how it carries the protagonist forward, sometimes without much thought, and yet they also reveal how each small ordinary decision defines as well as limits a character. The best writing about such shallow moments pulls the reader in and along by revealing the details that make the every day seem not so, well, everyday. Those are the moments that hint at and set up the tense expectation that things below the surface are not so calm, and that they are building to a crisis.
The deeper moments help the reader understand how a protagonist changes. The best writing about these deeper moments moves more slowly through the critical moments of the day, examining how much strength (depth of character, physical endurance, selflessness) it takes to make a change, and revealing the dire costs of that change (moral compromises, philosophical disjunction, physical pain, emotional trauma). The protagonist has to reconsider the trajectory of life and refine it to suit a new goal. That involves intense personal turmoil that displays itself on the interior as well as exterior.
Alternating between shallow and deep moments in a character’s life or story arc provides the reader with a trajectory that is neither always emotionally draining, nor endlessly breathless with events, but always alternating between the two.
Picture from http://www.watercolorpainting.com/brush_exercise_thickthin.htm