Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Omniscient)
As third person narrators go, this one really takes omniscience to new levels. Whereas most narrators only comment on a few characters within a very specific corner of the earth, taking a kind of bird's-eye view of a book's happenings, Catton's narrator looks at the novel's characters from space.
Yup, in addition to weaving in and out of characters' minds, this narrator is constantly reminding us that what's going on with the characters is related to/has a kind of twin in the machinery of the stars and planets. As s/he transitions us from the first section into the second, for example, s/he clues us into the changes that have taken place for the characters by commenting on what's been happening in the heavens:
For the planets have changed places against the wheeling canvas of the stars. The Sun has advanced one-twelfth along the tilted wheel of her ecliptic path, and with that motion comes a new world order, a new perspective on the whole. With the Sun in Capricorn we were reserved, exacting, and lofty in our distance. When we looked upon Man, we sought to fix him: we mourned his failures and measured his gifts. We could not imagine what he might have been, had he been tempted to betray his very nature—or had he betrayed himself without temptation, better still. But there is no truth except truth in relation, and heavenly relation is composed of wheels in motion, tilting axes, turning dials; it is a clockwork orchestration that alters every minute, never repeating, never still. (II.1.2)
So, yeah, our narrator is super ambitious and super omniscient. And apparently could read our fortune for us, if we asked.
The narrator likes to draw a lot of attention to herself/himself/itself, making sure the reader is aware of her/his/its role in framing events in a particular way. Quite a few times, s/he mentions omitting or reordering information to make the content easier for the reader to digest (and for that, we truly thank her/him).
For example, in giving us Balfour's account of the strange events that had been taking place in Hokitika, she let's us know she's cleaned it up quite a bit:
The interruptions were too tiresome, and Balfour's approach too digressive, to deserve a full and faithful record in the men's own words. We shall here excise their imperfections, and impose a regimental order upon the impatient chronicle of the shipping agent's roving mind; we shall apply our own mortar to the cracks and chinks of earthly recollection, and resurrect as new the edifice that, in solitary memory, exists only as a ruin. (I.2.2)
After all, Balfour was telling his story to a room of twelve other men, so naturally he was interrupted several times with questions, probably lost his place as a result, and surely told it in a disjointed fashion that have been a hard slog for a novel reader, had it been written out faithfully. So, our narrator smooths it out for us.
Also, the narrator likes to step into make sure we're thinking about the way the characters' destinies and futures are always shifting based on the tiniest of chances in circumstances or relationships. S/he comments several times upon how things could have turned out differently if it weren't for X or Y, drawing attention constantly to how these "dials" in the heavens—and in human relationships—never stop spinning.
For a great example of this, let's look at when we learn that Balfour had made the relatively tiny decision not to tell Ben Löwenthal everything about a certain conversation he had had with Alistair Lauderback—which, the narrator goes on to emphasize, actually had massive consequences:
We will interject to observe that this was a regrettable censorship; for if Balfour had recounted Lauderback's tale in full, the events of the 27th of January might have played out rather differently, for him—and for a number of other men. Prompted by certain particulars of Lauderback's story, Löwenthal would have remembered an event that he had not had reason to remember for many months: a memory that would have been of great assistance to Balfour's investigations of Carver, helping to explain, in part at least, that man's mysterious assumption of the surname Wells. (I.6.296)
So, the take-home is that the narrator may be omniscient, but s/she's never too busy or far away to interject something that will help guide the reader's insights at key moments.